49 files changed, 5943 insertions, 0 deletions

diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/BaseNode.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/BaseNode.java
new file mode 100644
index 00000000..2469d6bd
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/BaseNode.java
@@ -0,0 +1,108 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2012, Bergmann Gabor, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network;
+
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.TreeSet;
+
+import tools.refinery.viatra.runtime.rete.traceability.PatternTraceInfo;
+import tools.refinery.viatra.runtime.rete.traceability.TraceInfo;
+
+/**
+ * Base implementation for a Rete node.
+ * 
+ * @author Bergmann Gabor
+ * 
+ */
+public abstract class BaseNode implements Node {
+
+    protected ReteContainer reteContainer;
+    protected long nodeId;
+    protected Object tag;
+    protected Set<TraceInfo> traceInfos;
+
+    /**
+     * @param reteContainer
+     *            the container to create this node in
+     */
+    public BaseNode(ReteContainer reteContainer) {
+        super();
+        this.reteContainer = reteContainer;
+        this.nodeId = reteContainer.registerNode(this);
+        this.traceInfos = new HashSet<TraceInfo>();
+    }
+
+    @Override
+    public String toString() {
+        if (tag != null)
+            return toStringCore() + "->" + getTraceInfoPatternsEnumerated() + "{" + tag.toString() + "}";
+        else
+            return toStringCore() + "->" + getTraceInfoPatternsEnumerated();
+    }
+
+    /**
+     * clients should override this to append before the tag / trace indicators
+     */
+    protected String toStringCore() {
+        return "[" + nodeId + "]" + getClass().getSimpleName();
+    }
+
+    @Override
+    public ReteContainer getContainer() {
+        return reteContainer;
+    }
+
+    @Override
+    public long getNodeId() {
+        return nodeId;
+    }
+
+    @Override
+    public Object getTag() {
+        return tag;
+    }
+
+    @Override
+    public void setTag(Object tag) {
+        this.tag = tag;
+    }
+        
+    @Override
+    public Set<TraceInfo> getTraceInfos() {
+        return Collections.unmodifiableSet(traceInfos);
+    }
+    
+    @Override
+    public void assignTraceInfo(TraceInfo traceInfo) {
+        traceInfos.add(traceInfo);
+        traceInfo.assignNode(this);
+    }
+    
+    @Override
+    public void acceptPropagatedTraceInfo(TraceInfo traceInfo) {
+        assignTraceInfo(traceInfo);
+    }
+    
+    /**
+     * Descendants should use this in e.g. logging
+     */
+    protected String getTraceInfoPatternsEnumerated() {
+        TreeSet<String> patternNames = new TreeSet<String>();
+        for (TraceInfo trInfo : traceInfos) {
+            if (trInfo instanceof PatternTraceInfo) {
+                final String pName = ((PatternTraceInfo) trInfo).getPatternName();
+                patternNames.add(pName);
+            }
+        }
+        return patternNames.toString();
+    }
+
+}
\ No newline at end of file
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/ConnectionFactory.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/ConnectionFactory.java
new file mode 100644
index 00000000..b261d19d
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/ConnectionFactory.java
@@ -0,0 +1,171 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2014, Bergmann Gabor, Istvan Rath and Daniel Varro
+ * Copyright (c) 2023 The Refinery Authors <https://refinery.tools>
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.rete.aggregation.IndexerBasedAggregatorNode;
+import tools.refinery.viatra.runtime.rete.boundary.InputConnector;
+import tools.refinery.viatra.runtime.rete.eval.RelationEvaluatorNode;
+import tools.refinery.viatra.runtime.rete.index.DualInputNode;
+import tools.refinery.viatra.runtime.rete.index.Indexer;
+import tools.refinery.viatra.runtime.rete.index.IterableIndexer;
+import tools.refinery.viatra.runtime.rete.index.ProjectionIndexer;
+import tools.refinery.viatra.runtime.rete.recipes.*;
+import tools.refinery.viatra.runtime.rete.remote.Address;
+import tools.refinery.viatra.runtime.rete.traceability.RecipeTraceInfo;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+/**
+ * Class responsible for connecting freshly instantiating Rete nodes to their parents.
+ *
+ * @author Bergmann Gabor
+ *
+ */
+class ConnectionFactory {
+    ReteContainer reteContainer;
+
+    public ConnectionFactory(ReteContainer reteContainer) {
+        super();
+        this.reteContainer = reteContainer;
+    }
+
+    // TODO move to node implementation instead?
+    private boolean isStateful(ReteNodeRecipe recipe) {
+        return recipe instanceof ProjectionIndexerRecipe || recipe instanceof IndexerBasedAggregatorRecipe
+                || recipe instanceof SingleColumnAggregatorRecipe || recipe instanceof ExpressionEnforcerRecipe
+                || recipe instanceof TransitiveClosureRecipe || recipe instanceof ProductionRecipe
+                || recipe instanceof UniquenessEnforcerRecipe || recipe instanceof RelationEvaluationRecipe;
+
+    }
+
+    /**
+     * PRE: nodes for parent recipes must already be created and registered
+     * <p>
+     * PRE: must not be an input node (for which {@link InputConnector} is responsible)
+     */
+    public void connectToParents(RecipeTraceInfo recipeTrace, Node freshNode) {
+        final ReteNodeRecipe recipe = recipeTrace.getRecipe();
+        if (recipe instanceof ConstantRecipe) {
+            // NO-OP
+        } else if (recipe instanceof InputRecipe) {
+            throw new IllegalArgumentException(
+                    ConnectionFactory.class.getSimpleName() + " not intended for input connection: " + recipe);
+        } else if (recipe instanceof SingleParentNodeRecipe) {
+            final Receiver receiver = (Receiver) freshNode;
+            ReteNodeRecipe parentRecipe = ((SingleParentNodeRecipe) recipe).getParent();
+            connectToParent(recipe, receiver, parentRecipe);
+        } else if (recipe instanceof RelationEvaluationRecipe) {
+            List<ReteNodeRecipe> parentRecipes = ((MultiParentNodeRecipe) recipe).getParents();
+            List<Supplier> parentSuppliers = new ArrayList<Supplier>();
+            for (final ReteNodeRecipe parentRecipe : parentRecipes) {
+                parentSuppliers.add(getSupplierForRecipe(parentRecipe));
+            }
+            ((RelationEvaluatorNode) freshNode).connectToParents(parentSuppliers);
+        } else if (recipe instanceof BetaRecipe) {
+            final DualInputNode beta = (DualInputNode) freshNode;
+            final ArrayList<RecipeTraceInfo> parentTraces = new ArrayList<RecipeTraceInfo>(
+                    recipeTrace.getParentRecipeTraces());
+            Slots slots = avoidActiveNodeConflict(parentTraces.get(0), parentTraces.get(1));
+            beta.connectToIndexers(slots.primary, slots.secondary);
+        } else if (recipe instanceof IndexerBasedAggregatorRecipe) {
+            final IndexerBasedAggregatorNode aggregator = (IndexerBasedAggregatorNode) freshNode;
+            final IndexerBasedAggregatorRecipe aggregatorRecipe = (IndexerBasedAggregatorRecipe) recipe;
+            aggregator.initializeWith((ProjectionIndexer) resolveIndexer(aggregatorRecipe.getParent()));
+        } else if (recipe instanceof MultiParentNodeRecipe) {
+            final Receiver receiver = (Receiver) freshNode;
+            List<ReteNodeRecipe> parentRecipes = ((MultiParentNodeRecipe) recipe).getParents();
+            for (ReteNodeRecipe parentRecipe : parentRecipes) {
+                connectToParent(recipe, receiver, parentRecipe);
+            }
+        }
+    }
+
+    private Indexer resolveIndexer(final IndexerRecipe indexerRecipe) {
+        final Address<? extends Node> address = reteContainer.getNetwork().getExistingNodeByRecipe(indexerRecipe);
+        return (Indexer) reteContainer.resolveLocal(address);
+    }
+
+    private void connectToParent(ReteNodeRecipe recipe, Receiver freshNode, ReteNodeRecipe parentRecipe) {
+        final Supplier parentSupplier = getSupplierForRecipe(parentRecipe);
+
+        // special synch
+        if (freshNode instanceof ReinitializedNode) {
+            Collection<Tuple> tuples = new ArrayList<Tuple>();
+            parentSupplier.pullInto(tuples, true);
+            ((ReinitializedNode) freshNode).reinitializeWith(tuples);
+            reteContainer.connect(parentSupplier, freshNode);
+        } else { // default case
+            // stateless nodes do not have to be synced with contents UNLESS they already have children (recursive
+            // corner case)
+            if (isStateful(recipe)
+                    || ((freshNode instanceof Supplier) && !((Supplier) freshNode).getReceivers().isEmpty())) {
+                reteContainer.connectAndSynchronize(parentSupplier, freshNode);
+            } else {
+                // stateless node, no synch
+                reteContainer.connect(parentSupplier, freshNode);
+            }
+        }
+    }
+
+    private Supplier getSupplierForRecipe(ReteNodeRecipe recipe) {
+        @SuppressWarnings("unchecked")
+        final Address<? extends Supplier> parentAddress = (Address<? extends Supplier>) reteContainer.getNetwork()
+                .getExistingNodeByRecipe(recipe);
+        final Supplier supplier = reteContainer.getProvisioner().asSupplier(parentAddress);
+        return supplier;
+    }
+
+    /**
+     * If two indexers share their active node, joining them via DualInputNode is error-prone. Exception: coincidence of
+     * the two indexers is supported.
+     *
+     * @return a replacement for the secondary Indexers, if needed
+     */
+    private Slots avoidActiveNodeConflict(final RecipeTraceInfo primarySlot, final RecipeTraceInfo secondarySlot) {
+        Slots result = new Slots() {
+            {
+                primary = (IterableIndexer) resolveIndexer((ProjectionIndexerRecipe) primarySlot.getRecipe());
+                secondary = resolveIndexer((IndexerRecipe) secondarySlot.getRecipe());
+            }
+        };
+        if (activeNodeConflict(result.primary, result.secondary))
+            if (result.secondary instanceof IterableIndexer)
+                result.secondary = resolveActiveIndexer(secondarySlot);
+            else
+                result.primary = (IterableIndexer) resolveActiveIndexer(primarySlot);
+        return result;
+    }
+
+    private Indexer resolveActiveIndexer(final RecipeTraceInfo inactiveIndexerTrace) {
+        final RecipeTraceInfo activeIndexerTrace = reteContainer.getProvisioner()
+                .accessActiveIndexer(inactiveIndexerTrace);
+        reteContainer.getProvisioner().getOrCreateNodeByRecipe(activeIndexerTrace);
+        return resolveIndexer((ProjectionIndexerRecipe) activeIndexerTrace.getRecipe());
+    }
+
+    private static class Slots {
+        IterableIndexer primary;
+        Indexer secondary;
+    }
+
+    /**
+     * If two indexers share their active node, joining them via DualInputNode is error-prone. Exception: coincidence of
+     * the two indexers is supported.
+     *
+     * @return true if there is a conflict of active nodes.
+     */
+    private boolean activeNodeConflict(Indexer primarySlot, Indexer secondarySlot) {
+        return !primarySlot.equals(secondarySlot) && primarySlot.getActiveNode().equals(secondarySlot.getActiveNode());
+    }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/IGroupable.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/IGroupable.java
new file mode 100644
index 00000000..c22b06d8
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/IGroupable.java
@@ -0,0 +1,31 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2017, Gabor Bergmann, IncQueryLabs Ltd.
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network;
+
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationGroup;
+
+/**
+ * @author Gabor Bergmann
+ * @since 1.7
+ */
+public interface IGroupable {
+
+    /**
+     * @return the current group of the mailbox
+     * @since 1.7
+     */
+    CommunicationGroup getCurrentGroup();
+
+    /**
+     * Sets the current group of the mailbox
+     * @since 1.7
+     */
+    void setCurrentGroup(CommunicationGroup group);
+
+}
\ No newline at end of file
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/Network.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/Network.java
new file mode 100644
index 00000000..64f59ff3
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/Network.java
@@ -0,0 +1,408 @@
+/*******************************************************************************
+ * Copyright (c) 2004-2008 Gabor Bergmann and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+
+package tools.refinery.viatra.runtime.rete.network;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.util.CollectionsFactory;
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+import tools.refinery.viatra.runtime.rete.boundary.InputConnector;
+import tools.refinery.viatra.runtime.rete.matcher.ReteEngine;
+import tools.refinery.viatra.runtime.rete.recipes.ReteNodeRecipe;
+import tools.refinery.viatra.runtime.rete.remote.Address;
+import tools.refinery.viatra.runtime.rete.traceability.RecipeTraceInfo;
+import tools.refinery.viatra.runtime.rete.util.Options;
+
+/**
+ * @author Gabor Bergmann
+ * 
+ */
+public class Network {
+    final int threads;
+
+    protected ArrayList<ReteContainer> containers;
+    ReteContainer headContainer;
+    private int firstContainer = 0;
+    private int nextContainer = 0;
+
+    // the following fields exist only if threads > 0
+    protected Map<ReteContainer, Long> globalTerminationCriteria = null;
+    protected Map<ReteContainer, Long> reportedClocks = null;
+    protected Lock updateLock = null; // grab during normal update operations
+    protected Lock structuralChangeLock = null; // grab if the network structure
+                                                // is to
+    // be changed
+
+    // Knowledge of the outside world
+    private ReteEngine engine;
+    protected NodeFactory nodeFactory;
+    protected InputConnector inputConnector;
+
+    // Node and recipe administration
+    // incl. addresses for existing nodes by recipe (where available)
+    // Maintained by NodeProvisioner of each container
+    Map<ReteNodeRecipe, Address<? extends Node>> nodesByRecipe = CollectionsFactory.createMap();
+    Set<RecipeTraceInfo> recipeTraces = CollectionsFactory.createSet();
+
+    /**
+     * @throws IllegalStateException
+     *             if no node has been constructed for the recipe
+     */
+    public synchronized Address<? extends Node> getExistingNodeByRecipe(ReteNodeRecipe recipe) {
+        final Address<? extends Node> node = nodesByRecipe.get(recipe);
+        if (node == null)
+            throw new IllegalStateException(String.format("Rete node for recipe %s not constructed yet.", recipe));
+        return node;
+    }
+
+    /**
+     * @return null if no node has been constructed for the recipe
+     */
+    public synchronized Address<? extends Node> getNodeByRecipeIfExists(ReteNodeRecipe recipe) {
+        final Address<? extends Node> node = nodesByRecipe.get(recipe);
+        return node;
+    }
+
+    /**
+     * @param threads
+     *            the number of threads to operate the network with; 0 means single-threaded operation, 1 starts an
+     *            asynchronous thread to operate the RETE net, >1 uses multiple RETE containers.
+     */
+    public Network(int threads, ReteEngine engine) {
+        super();
+        this.threads = threads;
+        this.engine = engine;
+        this.inputConnector = new InputConnector(this);
+        this.nodeFactory = new NodeFactory(engine.getLogger());
+
+        containers = new ArrayList<ReteContainer>();
+        firstContainer = (threads > 1) ? Options.firstFreeContainer : 0; // NOPMD
+        nextContainer = firstContainer;
+
+        if (threads > 0) {
+            globalTerminationCriteria = CollectionsFactory.createMap();
+            reportedClocks = CollectionsFactory.createMap();
+            ReadWriteLock rwl = new ReentrantReadWriteLock();
+            updateLock = rwl.readLock();
+            structuralChangeLock = rwl.writeLock();
+            for (int i = 0; i < threads; ++i)
+                containers.add(new ReteContainer(this, true));
+        } else
+            containers.add(new ReteContainer(this, false));
+
+        headContainer = containers.get(0);
+    }
+
+    /**
+     * Kills this Network along with all containers and message consumption cycles.
+     */
+    public void kill() {
+        for (ReteContainer container : containers) {
+            container.kill();
+        }
+        containers.clear();
+    }
+
+    /**
+     * Returns the head container, that is guaranteed to reside in the same JVM as the Network object.
+     */
+    public ReteContainer getHeadContainer() {
+        return headContainer;
+    }
+
+    /**
+     * Returns the next container in round-robin fashion. Configurable not to yield head container.
+     */
+    public ReteContainer getNextContainer() {
+        if (nextContainer >= containers.size())
+            nextContainer = firstContainer;
+        return containers.get(nextContainer++);
+    }
+
+    /**
+     * Internal message delivery method.
+     * 
+     * @pre threads > 0
+     */
+    private void sendUpdate(Address<? extends Receiver> receiver, Direction direction, Tuple updateElement) {
+        ReteContainer affectedContainer = receiver.getContainer();
+        synchronized (globalTerminationCriteria) {
+            long newCriterion = affectedContainer.sendUpdateToLocalAddress(receiver, direction, updateElement);
+            terminationCriterion(affectedContainer, newCriterion);
+        }
+    }
+
+    /**
+     * Internal message delivery method for single-threaded operation
+     * 
+     * @pre threads == 0
+     */
+    private void sendUpdateSingleThreaded(Address<? extends Receiver> receiver, Direction direction,
+            Tuple updateElement) {
+        ReteContainer affectedContainer = receiver.getContainer();
+        affectedContainer.sendUpdateToLocalAddressSingleThreaded(receiver, direction, updateElement);
+    }
+
+    /**
+     * Internal message delivery method.
+     * 
+     * @pre threads > 0
+     */
+    private void sendUpdates(Address<? extends Receiver> receiver, Direction direction,
+            Collection<Tuple> updateElements) {
+        if (updateElements.isEmpty())
+            return;
+        ReteContainer affectedContainer = receiver.getContainer();
+        synchronized (globalTerminationCriteria) {
+            long newCriterion = affectedContainer.sendUpdatesToLocalAddress(receiver, direction, updateElements);
+            terminationCriterion(affectedContainer, newCriterion);
+        }
+    }
+
+    /**
+     * Sends an update message to the receiver node, indicating a newly found or lost partial matching. The node may
+     * reside in any of the containers associated with this network. To be called from a user thread during normal
+     * operation, NOT during construction.
+     * 
+     * @since 2.4
+     */
+    public void sendExternalUpdate(Address<? extends Receiver> receiver, Direction direction, Tuple updateElement) {
+        if (threads > 0) {
+            try {
+                updateLock.lock();
+                sendUpdate(receiver, direction, updateElement);
+            } finally {
+                updateLock.unlock();
+            }
+        } else {
+            sendUpdateSingleThreaded(receiver, direction, updateElement);
+            // getHeadContainer().
+        }
+    }
+
+    /**
+     * Sends an update message to the receiver node, indicating a newly found or lost partial matching. The node may
+     * reside in any of the containers associated with this network. To be called from a user thread during
+     * construction.
+     * 
+     * @pre: structuralChangeLock MUST be grabbed by the sequence (but not necessarily this thread, as the sequence may
+     *       span through network calls, that's why it's not enforced here )
+     * 
+     * @return the value of the target container's clock at the time when the message was accepted into its message
+     *         queue
+     * @since 2.4
+     */
+    public void sendConstructionUpdate(Address<? extends Receiver> receiver, Direction direction, Tuple updateElement) {
+        // structuralChangeLock.lock();
+        if (threads > 0)
+            sendUpdate(receiver, direction, updateElement);
+        else
+            receiver.getContainer().sendUpdateToLocalAddressSingleThreaded(receiver, direction, updateElement);
+        // structuralChangeLock.unlock();
+    }
+
+    /**
+     * Sends multiple update messages atomically to the receiver node, indicating a newly found or lost partial
+     * matching. The node may reside in any of the containers associated with this network. To be called from a user
+     * thread during construction.
+     * 
+     * @pre: structuralChangeLock MUST be grabbed by the sequence (but not necessarily this thread, as the sequence may
+     *       span through network calls, that's why it's not enforced here )
+     * 
+     * @since 2.4
+     */
+    public void sendConstructionUpdates(Address<? extends Receiver> receiver, Direction direction,
+            Collection<Tuple> updateElements) {
+        // structuralChangeLock.lock();
+        if (threads > 0)
+            sendUpdates(receiver, direction, updateElements);
+        else
+            receiver.getContainer().sendUpdatesToLocalAddressSingleThreaded(receiver, direction, updateElements);
+        // structuralChangeLock.unlock();
+    }
+
+    /**
+     * Establishes connection between a supplier and a receiver node, regardless which container they are in. Not to be
+     * called remotely, because this method enforces the structural lock.
+     * 
+     * @param supplier
+     * @param receiver
+     * @param synchronise
+     *            indicates whether the receiver should be synchronised to the current contents of the supplier
+     */
+    public void connectRemoteNodes(Address<? extends Supplier> supplier, Address<? extends Receiver> receiver,
+            boolean synchronise) {
+        try {
+            if (threads > 0)
+                structuralChangeLock.lock();
+            receiver.getContainer().connectRemoteNodes(supplier, receiver, synchronise);
+        } finally {
+            if (threads > 0)
+                structuralChangeLock.unlock();
+        }
+    }
+
+    /**
+     * Severs connection between a supplier and a receiver node, regardless which container they are in. Not to be
+     * called remotely, because this method enforces the structural lock.
+     * 
+     * @param supplier
+     * @param receiver
+     * @param desynchronise
+     *            indicates whether the current contents of the supplier should be subtracted from the receiver
+     */
+    public void disconnectRemoteNodes(Address<? extends Supplier> supplier, Address<? extends Receiver> receiver,
+            boolean desynchronise) {
+        try {
+            if (threads > 0)
+                structuralChangeLock.lock();
+            receiver.getContainer().disconnectRemoteNodes(supplier, receiver, desynchronise);
+        } finally {
+            if (threads > 0)
+                structuralChangeLock.unlock();
+        }
+    }
+
+    /**
+     * Containers use this method to report whenever they run out of messages in their queue.
+     * 
+     * To be called from the thread of the reporting container.
+     * 
+     * @pre threads > 0.
+     * @param reportingContainer
+     *            the container reporting the emptiness of its message queue.
+     * @param clock
+     *            the value of the container's clock when reporting.
+     * @param localTerminationCriteria
+     *            the latest clock values this container has received from other containers since the last time it
+     *            reported termination.
+     */
+    void reportLocalUpdateTermination(ReteContainer reportingContainer, long clock,
+            Map<ReteContainer, Long> localTerminationCriteria) {
+        synchronized (globalTerminationCriteria) {
+            for (Entry<ReteContainer, Long> criterion : localTerminationCriteria.entrySet()) {
+                terminationCriterion(criterion.getKey(), criterion.getValue());
+            }
+
+            reportedClocks.put(reportingContainer, clock);
+            Long criterion = globalTerminationCriteria.get(reportingContainer);
+            if (criterion != null && criterion < clock)
+                globalTerminationCriteria.remove(reportingContainer);
+
+            if (globalTerminationCriteria.isEmpty())
+                globalTerminationCriteria.notifyAll();
+        }
+    }
+
+    /**
+     * @pre threads > 0
+     */
+    private void terminationCriterion(ReteContainer affectedContainer, long newCriterion) {
+        synchronized (globalTerminationCriteria) {
+            Long oldCriterion = globalTerminationCriteria.get(affectedContainer);
+            Long oldClock = reportedClocks.get(affectedContainer);
+            long relevantClock = oldClock == null ? 0 : oldClock;
+            if ((relevantClock <= newCriterion) && (oldCriterion == null || oldCriterion < newCriterion)) {
+                globalTerminationCriteria.put(affectedContainer, newCriterion);
+            }
+        }
+    }
+
+    /**
+     * Waits until all rete update operations are settled in all containers. Returns immediately, if no updates are
+     * pending.
+     * 
+     * To be called from any user thread.
+     */
+    public void waitForReteTermination() {
+        if (threads > 0) {
+            synchronized (globalTerminationCriteria) {
+                while (!globalTerminationCriteria.isEmpty()) {
+                    try {
+                        globalTerminationCriteria.wait();
+                    } catch (InterruptedException e) {
+
+                    }
+                }
+            }
+        } else
+            headContainer.deliverMessagesSingleThreaded();
+    }
+
+    /**
+     * Waits to execute action until all rete update operations are settled in all containers. Runs action and returns
+     * immediately, if no updates are pending. The given action is guaranteed to be run when the terminated state still
+     * persists.
+     * 
+     * @param action
+     *            the action to be run when reaching the steady-state.
+     * 
+     *            To be called from any user thread.
+     */
+    public void waitForReteTermination(Runnable action) {
+        if (threads > 0) {
+            synchronized (globalTerminationCriteria) {
+                while (!globalTerminationCriteria.isEmpty()) {
+                    try {
+                        globalTerminationCriteria.wait();
+                    } catch (InterruptedException e) {
+
+                    }
+                }
+                action.run();
+            }
+        } else {
+            headContainer.deliverMessagesSingleThreaded();
+            action.run();
+        }
+
+    }
+
+    /**
+     * @return an unmodifiable set of known recipe traces
+     */
+    public Set<RecipeTraceInfo> getRecipeTraces() {
+        return Collections.unmodifiableSet(recipeTraces);
+    }
+
+    /**
+     * @return an unmodifiable list of containers
+     */
+    public List<ReteContainer> getContainers() {
+        return Collections.unmodifiableList(containers);
+    }
+
+    public Lock getStructuralChangeLock() {
+        return structuralChangeLock;
+    }
+
+    public NodeFactory getNodeFactory() {
+        return nodeFactory;
+    }
+
+    public InputConnector getInputConnector() {
+        return inputConnector;
+    }
+
+    public ReteEngine getEngine() {
+        return engine;
+    }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/NetworkStructureChangeSensitiveNode.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/NetworkStructureChangeSensitiveNode.java
new file mode 100644
index 00000000..c6ba34c4
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/NetworkStructureChangeSensitiveNode.java
@@ -0,0 +1,30 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2019, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network;
+
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationTracker;
+
+/**
+ * {@link Node}s implementing this interface are sensitive to changes in the dependency graph maintained by the
+ * {@link CommunicationTracker}. The {@link CommunicationTracker} notifies these nodes whenever the SCC of this node is
+ * affected by changes to the dependency graph. Depending on whether this node is contained in a recursive group or not,
+ * it may behave differently, and the {@link NetworkStructureChangeSensitiveNode#networkStructureChanged()} method can
+ * be used to perform changes in behavior.
+ * 
+ * @author Tamas Szabo
+ * @since 2.3
+ */
+public interface NetworkStructureChangeSensitiveNode extends Node {
+
+    /**
+     * At the time of the invocation, the dependency graph has already been updated.
+     */
+    public void networkStructureChanged();
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/Node.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/Node.java
new file mode 100644
index 00000000..e8ab615a
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/Node.java
@@ -0,0 +1,62 @@
+/*******************************************************************************
+ * Copyright (c) 2004-2008 Gabor Bergmann and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+
+package tools.refinery.viatra.runtime.rete.network;
+
+import java.util.Set;
+
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationTracker;
+import tools.refinery.viatra.runtime.rete.traceability.TraceInfo;
+
+/**
+ * A node of a rete network, should be uniquely identified by network and nodeId. NodeId can be requested by registering
+ * at the Network on construction.
+ * 
+ * @author Gabor Bergmann
+ */
+public interface Node {
+    /**
+     * @return the network this node belongs to.
+     */
+    ReteContainer getContainer();
+
+    /**
+     * @return the identifier unique to this node within the network.
+     */
+    long getNodeId();
+
+    /**
+     * Assigns a descriptive tag to the node
+     */
+    void setTag(Object tag);
+
+    /**
+     * @return the tag of the node
+     */
+    Object getTag();
+    
+    /**
+     * @return unmodifiable view of the list of traceability infos assigned to this node
+     */
+    Set<TraceInfo> getTraceInfos();
+    
+    /**
+     * assigns new traceability info to this node
+     */
+    void assignTraceInfo(TraceInfo traceInfo);
+    /**
+     * accepts traceability info propagated to this node
+     */
+    void acceptPropagatedTraceInfo(TraceInfo traceInfo);
+    
+    default CommunicationTracker getCommunicationTracker() {
+        return getContainer().getCommunicationTracker();
+    }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/NodeFactory.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/NodeFactory.java
new file mode 100644
index 00000000..3e4ea4e0
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/NodeFactory.java
@@ -0,0 +1,376 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2014, Bergmann Gabor, Istvan Rath and Daniel Varro
+ * Copyright (c) 2023 The Refinery Authors <https://refinery.tools>
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network;
+
+import org.apache.log4j.Logger;
+import org.eclipse.emf.common.util.EMap;
+import tools.refinery.viatra.runtime.rete.itc.alg.representative.RepresentativeElectionAlgorithm;
+import tools.refinery.viatra.runtime.rete.itc.alg.representative.StronglyConnectedComponentAlgorithm;
+import tools.refinery.viatra.runtime.rete.itc.alg.representative.WeaklyConnectedComponentAlgorithm;
+import tools.refinery.viatra.runtime.matchers.context.IPosetComparator;
+import tools.refinery.viatra.runtime.matchers.psystem.IExpressionEvaluator;
+import tools.refinery.viatra.runtime.matchers.psystem.IRelationEvaluator;
+import tools.refinery.viatra.runtime.matchers.psystem.aggregations.IMultisetAggregationOperator;
+import tools.refinery.viatra.runtime.matchers.tuple.TupleMask;
+import tools.refinery.viatra.runtime.matchers.tuple.Tuples;
+import tools.refinery.viatra.runtime.rete.aggregation.ColumnAggregatorNode;
+import tools.refinery.viatra.runtime.rete.aggregation.CountNode;
+import tools.refinery.viatra.runtime.rete.aggregation.IAggregatorNode;
+import tools.refinery.viatra.runtime.rete.aggregation.timely.FaithfulParallelTimelyColumnAggregatorNode;
+import tools.refinery.viatra.runtime.rete.aggregation.timely.FaithfulSequentialTimelyColumnAggregatorNode;
+import tools.refinery.viatra.runtime.rete.aggregation.timely.FirstOnlyParallelTimelyColumnAggregatorNode;
+import tools.refinery.viatra.runtime.rete.aggregation.timely.FirstOnlySequentialTimelyColumnAggregatorNode;
+import tools.refinery.viatra.runtime.rete.boundary.ExternalInputEnumeratorNode;
+import tools.refinery.viatra.runtime.rete.boundary.ExternalInputStatelessFilterNode;
+import tools.refinery.viatra.runtime.rete.eval.EvaluatorCore;
+import tools.refinery.viatra.runtime.rete.eval.MemorylessEvaluatorNode;
+import tools.refinery.viatra.runtime.rete.eval.OutputCachingEvaluatorNode;
+import tools.refinery.viatra.runtime.rete.eval.RelationEvaluatorNode;
+import tools.refinery.viatra.runtime.rete.index.ExistenceNode;
+import tools.refinery.viatra.runtime.rete.index.Indexer;
+import tools.refinery.viatra.runtime.rete.index.JoinNode;
+import tools.refinery.viatra.runtime.rete.matcher.TimelyConfiguration;
+import tools.refinery.viatra.runtime.rete.matcher.TimelyConfiguration.AggregatorArchitecture;
+import tools.refinery.viatra.runtime.rete.matcher.TimelyConfiguration.TimelineRepresentation;
+import tools.refinery.viatra.runtime.rete.misc.ConstantNode;
+import tools.refinery.viatra.runtime.rete.recipes.*;
+import tools.refinery.viatra.runtime.rete.single.*;
+import tools.refinery.viatra.runtime.rete.traceability.TraceInfo;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Factory for instantiating Rete nodes. The created nodes are not connected to the network yet.
+ *
+ * @author Bergmann Gabor
+ *
+ */
+class NodeFactory {
+    Logger logger;
+
+    public NodeFactory(Logger logger) {
+        super();
+        this.logger = logger;
+    }
+
+    /**
+     * PRE: parent node must already be created
+     */
+    public Indexer createIndexer(ReteContainer reteContainer, IndexerRecipe recipe, Supplier parentNode,
+            TraceInfo... traces) {
+
+        if (recipe instanceof ProjectionIndexerRecipe) {
+            return parentNode.constructIndex(toMask(recipe.getMask()), traces);
+            // already traced
+        } else if (recipe instanceof AggregatorIndexerRecipe) {
+            int indexOfAggregateResult = recipe.getParent().getArity();
+            int resultPosition = recipe.getMask().getSourceIndices().lastIndexOf(indexOfAggregateResult);
+
+            IAggregatorNode aggregatorNode = (IAggregatorNode) parentNode;
+            final Indexer result = (resultPosition == -1) ? aggregatorNode.getAggregatorOuterIndexer()
+                    : aggregatorNode.getAggregatorOuterIdentityIndexer(resultPosition);
+
+            for (TraceInfo traceInfo : traces)
+                result.assignTraceInfo(traceInfo);
+            return result;
+        } else
+            throw new IllegalArgumentException("Unkown Indexer recipe: " + recipe);
+    }
+
+    /**
+     * PRE: recipe is not an indexer recipe.
+     */
+    public Supplier createNode(ReteContainer reteContainer, ReteNodeRecipe recipe, TraceInfo... traces) {
+        if (recipe instanceof IndexerRecipe)
+            throw new IllegalArgumentException("Indexers are not created by NodeFactory: " + recipe);
+
+        Supplier result = instantiateNodeDispatch(reteContainer, recipe);
+        for (TraceInfo traceInfo : traces)
+            result.assignTraceInfo(traceInfo);
+        return result;
+    }
+
+    private Supplier instantiateNodeDispatch(ReteContainer reteContainer, ReteNodeRecipe recipe) {
+
+        // Parentless
+
+        if (recipe instanceof ConstantRecipe)
+            return instantiateNode(reteContainer, (ConstantRecipe) recipe);
+        if (recipe instanceof InputRecipe)
+            return instantiateNode(reteContainer, (InputRecipe) recipe);
+
+        // SingleParentNodeRecipe
+
+        // if (recipe instanceof ProjectionIndexer)
+        // return instantiateNode((ProjectionIndexer)recipe);
+        if (recipe instanceof InputFilterRecipe)
+            return instantiateNode(reteContainer, (InputFilterRecipe) recipe);
+        if (recipe instanceof InequalityFilterRecipe)
+            return instantiateNode(reteContainer, (InequalityFilterRecipe) recipe);
+        if (recipe instanceof EqualityFilterRecipe)
+            return instantiateNode(reteContainer, (EqualityFilterRecipe) recipe);
+        if (recipe instanceof TransparentRecipe)
+            return instantiateNode(reteContainer, (TransparentRecipe) recipe);
+        if (recipe instanceof TrimmerRecipe)
+            return instantiateNode(reteContainer, (TrimmerRecipe) recipe);
+        if (recipe instanceof TransitiveClosureRecipe)
+            return instantiateNode(reteContainer, (TransitiveClosureRecipe) recipe);
+                if (recipe instanceof RepresentativeElectionRecipe)
+                        return instantiateNode(reteContainer, (RepresentativeElectionRecipe) recipe);
+        if (recipe instanceof RelationEvaluationRecipe)
+            return instantiateNode(reteContainer, (RelationEvaluationRecipe) recipe);
+        if (recipe instanceof ExpressionEnforcerRecipe)
+            return instantiateNode(reteContainer, (ExpressionEnforcerRecipe) recipe);
+        if (recipe instanceof CountAggregatorRecipe)
+            return instantiateNode(reteContainer, (CountAggregatorRecipe) recipe);
+        if (recipe instanceof SingleColumnAggregatorRecipe)
+            return instantiateNode(reteContainer, (SingleColumnAggregatorRecipe) recipe);
+        if (recipe instanceof DiscriminatorDispatcherRecipe)
+            return instantiateNode(reteContainer, (DiscriminatorDispatcherRecipe) recipe);
+        if (recipe instanceof DiscriminatorBucketRecipe)
+            return instantiateNode(reteContainer, (DiscriminatorBucketRecipe) recipe);
+
+        // MultiParentNodeRecipe
+        if (recipe instanceof UniquenessEnforcerRecipe)
+            return instantiateNode(reteContainer, (UniquenessEnforcerRecipe) recipe);
+        if (recipe instanceof ProductionRecipe)
+            return instantiateNode(reteContainer, (ProductionRecipe) recipe);
+
+        // BetaNodeRecipe
+        if (recipe instanceof JoinRecipe)
+            return instantiateNode(reteContainer, (JoinRecipe) recipe);
+        if (recipe instanceof SemiJoinRecipe)
+            return instantiateNode(reteContainer, (SemiJoinRecipe) recipe);
+        if (recipe instanceof AntiJoinRecipe)
+            return instantiateNode(reteContainer, (AntiJoinRecipe) recipe);
+
+        // ... else
+        throw new IllegalArgumentException("Unsupported recipe type: " + recipe);
+    }
+
+    // INSTANTIATION for recipe types
+
+    private Supplier instantiateNode(ReteContainer reteContainer, InputRecipe recipe) {
+        return new ExternalInputEnumeratorNode(reteContainer);
+    }
+
+    private Supplier instantiateNode(ReteContainer reteContainer, InputFilterRecipe recipe) {
+        return new ExternalInputStatelessFilterNode(reteContainer, toMaskOrNull(recipe.getMask()));
+    }
+
+    private Supplier instantiateNode(ReteContainer reteContainer, CountAggregatorRecipe recipe) {
+        return new CountNode(reteContainer);
+    }
+
+    private Supplier instantiateNode(ReteContainer reteContainer, TransparentRecipe recipe) {
+        return new TransparentNode(reteContainer);
+    }
+
+    private Supplier instantiateNode(ReteContainer reteContainer, ExpressionEnforcerRecipe recipe) {
+        final IExpressionEvaluator evaluator = toIExpressionEvaluator(recipe.getExpression());
+        final Map<String, Integer> posMapping = toStringIndexMap(recipe.getMappedIndices());
+        final int sourceTupleWidth = recipe.getParent().getArity();
+        EvaluatorCore core = null;
+        if (recipe instanceof CheckRecipe) {
+            core = new EvaluatorCore.PredicateEvaluatorCore(logger, evaluator, posMapping, sourceTupleWidth);
+        } else if (recipe instanceof EvalRecipe) {
+            final boolean isUnwinding = ((EvalRecipe) recipe).isUnwinding();
+            core = new EvaluatorCore.FunctionEvaluatorCore(logger, evaluator, posMapping, sourceTupleWidth, isUnwinding);
+        } else {
+            throw new IllegalArgumentException("Unhandled expression enforcer recipe: " + recipe.getClass() + "!");
+        }
+        if (recipe.isCacheOutput()) {
+            return new OutputCachingEvaluatorNode(reteContainer, core);
+        } else {
+            return new MemorylessEvaluatorNode(reteContainer, core);
+        }
+    }
+
+    @SuppressWarnings({ "rawtypes", "unchecked" })
+    private Supplier instantiateNode(ReteContainer reteContainer, SingleColumnAggregatorRecipe recipe) {
+        final IMultisetAggregationOperator operator = recipe.getMultisetAggregationOperator();
+        TupleMask coreMask = null;
+        if (recipe.getOptionalMonotonicityInfo() != null) {
+            coreMask = toMask(recipe.getOptionalMonotonicityInfo().getCoreMask());
+        } else {
+            coreMask = toMask(recipe.getGroupByMask());
+        }
+
+        if (reteContainer.isTimelyEvaluation()) {
+            final TimelyConfiguration timelyConfiguration = reteContainer.getTimelyConfiguration();
+            final AggregatorArchitecture aggregatorArchitecture = timelyConfiguration.getAggregatorArchitecture();
+            final TimelineRepresentation timelineRepresentation = timelyConfiguration.getTimelineRepresentation();
+
+            TupleMask posetMask = null;
+
+            if (recipe.getOptionalMonotonicityInfo() != null) {
+                posetMask = toMask(recipe.getOptionalMonotonicityInfo().getPosetMask());
+            } else {
+                final int aggregatedColumn = recipe.getAggregableIndex();
+                posetMask = TupleMask.selectSingle(aggregatedColumn, coreMask.sourceWidth);
+            }
+
+            if (timelineRepresentation == TimelineRepresentation.FIRST_ONLY
+                    && aggregatorArchitecture == AggregatorArchitecture.SEQUENTIAL) {
+                return new FirstOnlySequentialTimelyColumnAggregatorNode(reteContainer, operator, coreMask, posetMask);
+            } else if (timelineRepresentation == TimelineRepresentation.FIRST_ONLY
+                    && aggregatorArchitecture == AggregatorArchitecture.PARALLEL) {
+                return new FirstOnlyParallelTimelyColumnAggregatorNode(reteContainer, operator, coreMask, posetMask);
+            } else if (timelineRepresentation == TimelineRepresentation.FAITHFUL
+                    && aggregatorArchitecture == AggregatorArchitecture.SEQUENTIAL) {
+                return new FaithfulSequentialTimelyColumnAggregatorNode(reteContainer, operator, coreMask, posetMask);
+            } else if (timelineRepresentation == TimelineRepresentation.FAITHFUL
+                    && aggregatorArchitecture == AggregatorArchitecture.PARALLEL) {
+                return new FaithfulParallelTimelyColumnAggregatorNode(reteContainer, operator, coreMask, posetMask);
+            } else {
+                throw new IllegalArgumentException("Unsupported timely configuration!");
+            }
+        } else if (recipe.isDeleteRederiveEvaluation() && recipe.getOptionalMonotonicityInfo() != null) {
+            final TupleMask posetMask = toMask(recipe.getOptionalMonotonicityInfo().getPosetMask());
+            final IPosetComparator posetComparator = (IPosetComparator) recipe.getOptionalMonotonicityInfo()
+                    .getPosetComparator();
+            return new ColumnAggregatorNode(reteContainer, operator, recipe.isDeleteRederiveEvaluation(), coreMask,
+                    posetMask, posetComparator);
+        } else {
+            final int aggregatedColumn = recipe.getAggregableIndex();
+            return new ColumnAggregatorNode(reteContainer, operator, coreMask, aggregatedColumn);
+        }
+    }
+
+    private Supplier instantiateNode(ReteContainer reteContainer, TransitiveClosureRecipe recipe) {
+        return new TransitiveClosureNode(reteContainer);
+    }
+
+        private Supplier instantiateNode(ReteContainer reteContainer, RepresentativeElectionRecipe recipe) {
+                RepresentativeElectionAlgorithm.Factory algorithmFactory = switch (recipe.getConnectivity()) {
+                        case STRONG -> StronglyConnectedComponentAlgorithm::new;
+                        case WEAK -> WeaklyConnectedComponentAlgorithm::new;
+                };
+                return new RepresentativeElectionNode(reteContainer, algorithmFactory);
+        }
+
+    private Supplier instantiateNode(ReteContainer reteContainer, RelationEvaluationRecipe recipe) {
+        return new RelationEvaluatorNode(reteContainer, toIRelationEvaluator(recipe.getEvaluator()));
+    }
+
+    private Supplier instantiateNode(ReteContainer reteContainer, ProductionRecipe recipe) {
+        if (reteContainer.isTimelyEvaluation()) {
+            return new TimelyProductionNode(reteContainer, toStringIndexMap(recipe.getMappedIndices()));
+        } else if (recipe.isDeleteRederiveEvaluation() && recipe.getOptionalMonotonicityInfo() != null) {
+            TupleMask coreMask = toMask(recipe.getOptionalMonotonicityInfo().getCoreMask());
+            TupleMask posetMask = toMask(recipe.getOptionalMonotonicityInfo().getPosetMask());
+            IPosetComparator posetComparator = (IPosetComparator) recipe.getOptionalMonotonicityInfo()
+                    .getPosetComparator();
+            return new DefaultProductionNode(reteContainer, toStringIndexMap(recipe.getMappedIndices()),
+                    recipe.isDeleteRederiveEvaluation(), coreMask, posetMask, posetComparator);
+        } else {
+            return new DefaultProductionNode(reteContainer, toStringIndexMap(recipe.getMappedIndices()),
+                    recipe.isDeleteRederiveEvaluation());
+        }
+    }
+
+    private Supplier instantiateNode(ReteContainer reteContainer, UniquenessEnforcerRecipe recipe) {
+        if (reteContainer.isTimelyEvaluation()) {
+            return new TimelyUniquenessEnforcerNode(reteContainer, recipe.getArity());
+        } else if (recipe.isDeleteRederiveEvaluation() && recipe.getOptionalMonotonicityInfo() != null) {
+            TupleMask coreMask = toMask(recipe.getOptionalMonotonicityInfo().getCoreMask());
+            TupleMask posetMask = toMask(recipe.getOptionalMonotonicityInfo().getPosetMask());
+            IPosetComparator posetComparator = (IPosetComparator) recipe.getOptionalMonotonicityInfo()
+                    .getPosetComparator();
+            return new UniquenessEnforcerNode(reteContainer, recipe.getArity(), recipe.isDeleteRederiveEvaluation(),
+                    coreMask, posetMask, posetComparator);
+        } else {
+            return new UniquenessEnforcerNode(reteContainer, recipe.getArity(), recipe.isDeleteRederiveEvaluation());
+        }
+    }
+
+    private Supplier instantiateNode(ReteContainer reteContainer, ConstantRecipe recipe) {
+        final List<Object> constantValues = recipe.getConstantValues();
+        final Object[] constantArray = constantValues.toArray(new Object[constantValues.size()]);
+        return new ConstantNode(reteContainer, Tuples.flatTupleOf(constantArray));
+    }
+
+    private Supplier instantiateNode(ReteContainer reteContainer, DiscriminatorBucketRecipe recipe) {
+        return new DiscriminatorBucketNode(reteContainer, recipe.getBucketKey());
+    }
+
+    private Supplier instantiateNode(ReteContainer reteContainer, DiscriminatorDispatcherRecipe recipe) {
+        return new DiscriminatorDispatcherNode(reteContainer, recipe.getDiscriminationColumnIndex());
+    }
+
+    private Supplier instantiateNode(ReteContainer reteContainer, TrimmerRecipe recipe) {
+        return new TrimmerNode(reteContainer, toMask(recipe.getMask()));
+    }
+
+    private Supplier instantiateNode(ReteContainer reteContainer, InequalityFilterRecipe recipe) {
+        Tunnel result = new InequalityFilterNode(reteContainer, recipe.getSubject(),
+                TupleMask.fromSelectedIndices(recipe.getParent().getArity(), recipe.getInequals()));
+        return result;
+    }
+
+    private Supplier instantiateNode(ReteContainer reteContainer, EqualityFilterRecipe recipe) {
+        final int[] equalIndices = TupleMask.integersToIntArray(recipe.getIndices());
+        return new EqualityFilterNode(reteContainer, equalIndices);
+    }
+
+    private Supplier instantiateNode(ReteContainer reteContainer, AntiJoinRecipe recipe) {
+        return new ExistenceNode(reteContainer, true);
+    }
+
+    private Supplier instantiateNode(ReteContainer reteContainer, SemiJoinRecipe recipe) {
+        return new ExistenceNode(reteContainer, false);
+    }
+
+    private Supplier instantiateNode(ReteContainer reteContainer, JoinRecipe recipe) {
+        return new JoinNode(reteContainer, toMask(recipe.getRightParentComplementaryMask()));
+    }
+
+    // HELPERS
+
+    private IExpressionEvaluator toIExpressionEvaluator(ExpressionDefinition expressionDefinition) {
+        final Object evaluator = expressionDefinition.getEvaluator();
+        if (evaluator instanceof IExpressionEvaluator) {
+            return (IExpressionEvaluator) evaluator;
+        }
+        throw new IllegalArgumentException("No runtime support for expression evaluator: " + evaluator);
+    }
+
+    private IRelationEvaluator toIRelationEvaluator(ExpressionDefinition expressionDefinition) {
+        final Object evaluator = expressionDefinition.getEvaluator();
+        if (evaluator instanceof IRelationEvaluator) {
+            return (IRelationEvaluator) evaluator;
+        }
+        throw new IllegalArgumentException("No runtime support for relation evaluator: " + evaluator);
+    }
+
+    private Map<String, Integer> toStringIndexMap(final EMap<String, Integer> mappedIndices) {
+        final HashMap<String, Integer> result = new HashMap<String, Integer>();
+        for (java.util.Map.Entry<String, Integer> entry : mappedIndices) {
+            result.put(entry.getKey(), entry.getValue());
+        }
+        return result;
+    }
+
+    /** Mask can be null */
+    private TupleMask toMaskOrNull(Mask mask) {
+        if (mask == null)
+            return null;
+        else
+            return toMask(mask);
+    }
+
+    /** Mask is non-null. */
+    private TupleMask toMask(Mask mask) {
+        return TupleMask.fromSelectedIndices(mask.getSourceArity(), mask.getSourceIndices());
+    }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/NodeProvisioner.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/NodeProvisioner.java
new file mode 100644
index 00000000..9121fc44
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/NodeProvisioner.java
@@ -0,0 +1,346 @@
+/*******************************************************************************
+ * Copyright (c) 2004-2008 Gabor Bergmann and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+
+package tools.refinery.viatra.runtime.rete.network;
+
+import tools.refinery.viatra.runtime.matchers.context.IQueryRuntimeContext;
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.tuple.TupleMask;
+import tools.refinery.viatra.runtime.matchers.tuple.Tuples;
+import tools.refinery.viatra.runtime.matchers.util.CollectionsFactory;
+import tools.refinery.viatra.runtime.rete.boundary.InputConnector;
+import tools.refinery.viatra.runtime.rete.construction.plancompiler.CompilerHelper;
+import tools.refinery.viatra.runtime.rete.index.Indexer;
+import tools.refinery.viatra.runtime.rete.index.OnetimeIndexer;
+import tools.refinery.viatra.runtime.rete.index.ProjectionIndexer;
+import tools.refinery.viatra.runtime.rete.network.delayed.DelayedConnectCommand;
+import tools.refinery.viatra.runtime.rete.recipes.*;
+import tools.refinery.viatra.runtime.rete.recipes.helper.RecipeRecognizer;
+import tools.refinery.viatra.runtime.rete.recipes.helper.RecipesHelper;
+import tools.refinery.viatra.runtime.rete.remote.Address;
+import tools.refinery.viatra.runtime.rete.remote.RemoteReceiver;
+import tools.refinery.viatra.runtime.rete.remote.RemoteSupplier;
+import tools.refinery.viatra.runtime.rete.traceability.ActiveNodeConflictTrace;
+import tools.refinery.viatra.runtime.rete.traceability.RecipeTraceInfo;
+import tools.refinery.viatra.runtime.rete.traceability.UserRequestTrace;
+import tools.refinery.viatra.runtime.rete.util.Options;
+
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * Stores the internal parts of a rete network. Nodes are stored according to type and parameters.
+ *
+ * @author Gabor Bergmann
+ */
+public class NodeProvisioner {
+
+    // boolean activeStorage = true;
+
+    ReteContainer reteContainer;
+    NodeFactory nodeFactory;
+    ConnectionFactory connectionFactory;
+    InputConnector inputConnector;
+    IQueryRuntimeContext runtimeContext;
+
+    // TODO as recipe?
+    Map<Supplier, RemoteReceiver> remoteReceivers = CollectionsFactory.createMap();
+    Map<Address<? extends Supplier>, RemoteSupplier> remoteSuppliers = CollectionsFactory.createMap();
+
+    private RecipeRecognizer recognizer;
+
+    /**
+     * PRE: NodeFactory, ConnectionFactory must exist
+     *
+     * @param reteContainer
+     *            the ReteNet whose interior is to be mapped.
+     */
+    public NodeProvisioner(ReteContainer reteContainer) {
+        super();
+        this.reteContainer = reteContainer;
+        this.nodeFactory = reteContainer.getNodeFactory();
+        this.connectionFactory = reteContainer.getConnectionFactory();
+        this.inputConnector = reteContainer.getInputConnectionFactory();
+        runtimeContext = reteContainer.getNetwork().getEngine().getRuntimeContext();
+        recognizer = new RecipeRecognizer(runtimeContext);
+    }
+
+    public synchronized Address<? extends Node> getOrCreateNodeByRecipe(RecipeTraceInfo recipeTrace) {
+        ReteNodeRecipe recipe = recipeTrace.getRecipe();
+        Address<? extends Node> result = getNodesByRecipe().get(recipe);
+        if (result != null) {
+            // NODE ALREADY CONSTRUCTED FOR RECIPE, only needs to add trace
+            if (getRecipeTraces().add(recipeTrace))
+                result.getNodeCache().assignTraceInfo(recipeTrace);
+        } else {
+            // No node for this recipe object - but equivalent recipes still
+            // reusable
+            ReteNodeRecipe canonicalRecipe = recognizer.canonicalizeRecipe(recipe);
+            if (canonicalRecipe != recipe) {
+                // FOUND EQUIVALENT RECIPE
+                result = getNodesByRecipe().get(canonicalRecipe);
+                if (result != null) {
+                    // NODE ALREADY CONSTRUCTED FOR EQUIVALENT RECIPE
+                    recipeTrace.shadowWithEquivalentRecipe(canonicalRecipe);
+                    getNodesByRecipe().put(recipe, result);
+                    if (getRecipeTraces().add(recipeTrace))
+                        result.getNodeCache().assignTraceInfo(recipeTrace);
+                    // Bug 491922: ensure that recipe shadowing propagates to
+                    // parent traces
+                    // note that if equivalentRecipes() becomes more
+                    // sophisticated
+                    // and considers recipes with different parents, this might
+                    // have to be changed
+                    ensureParents(recipeTrace);
+                } else {
+                    // CONSTRUCTION IN PROGRESS FOR EQUIVALENT RECIPE
+                    if (recipe instanceof IndexerRecipe) {
+                        // this is allowed for indexers;
+                        // go on with the construction, as the same indexer node
+                        // will be obtained anyways
+                    } else {
+                        throw new IllegalStateException(
+                                "This should not happen: " + "non-indexer nodes are are supposed to be constructed "
+                                        + "as soon as they are designated as canonical recipes");
+                    }
+                }
+            }
+            if (result == null) {
+                // MUST INSTANTIATE NEW NODE FOR RECIPE
+                final Node freshNode = instantiateNodeForRecipe(recipeTrace, recipe);
+                result = reteContainer.makeAddress(freshNode);
+            }
+        }
+        return result;
+    }
+
+    private Set<RecipeTraceInfo> getRecipeTraces() {
+        return reteContainer.network.recipeTraces;
+    }
+
+    private Node instantiateNodeForRecipe(RecipeTraceInfo recipeTrace, final ReteNodeRecipe recipe) {
+        this.getRecipeTraces().add(recipeTrace);
+        if (recipe instanceof IndexerRecipe) {
+
+            // INSTANTIATE AND HOOK UP
+            // (cannot delay hooking up, because parent determines indexer
+            // implementation)
+            ensureParents(recipeTrace);
+            final ReteNodeRecipe parentRecipe = recipeTrace.getParentRecipeTraces().iterator().next().getRecipe();
+            final Indexer result = nodeFactory.createIndexer(reteContainer, (IndexerRecipe) recipe,
+                    asSupplier(
+                            (Address<? extends Supplier>) reteContainer.network.getExistingNodeByRecipe(parentRecipe)),
+                    recipeTrace);
+
+            // REMEMBER
+            if (Options.nodeSharingOption != Options.NodeSharingOption.NEVER) {
+                getNodesByRecipe().put(recipe, reteContainer.makeAddress(result));
+            }
+
+            return result;
+        } else {
+
+            // INSTANTIATE
+            Node result = nodeFactory.createNode(reteContainer, recipe, recipeTrace);
+
+            // REMEMBER
+            if (Options.nodeSharingOption == Options.NodeSharingOption.ALL) {
+                getNodesByRecipe().put(recipe, reteContainer.makeAddress(result));
+            }
+
+            // HOOK UP
+            // (recursion-tolerant due to this delayed order of initialization)
+            if (recipe instanceof InputRecipe) {
+                inputConnector.connectInput((InputRecipe) recipe, result);
+            } else {
+                if (recipe instanceof InputFilterRecipe)
+                    inputConnector.connectInputFilter((InputFilterRecipe) recipe, result);
+                ensureParents(recipeTrace);
+                connectionFactory.connectToParents(recipeTrace, result);
+            }
+            return result;
+        }
+    }
+
+    private Map<ReteNodeRecipe, Address<? extends Node>> getNodesByRecipe() {
+        return reteContainer.network.nodesByRecipe;
+    }
+
+    private void ensureParents(RecipeTraceInfo recipeTrace) {
+        for (RecipeTraceInfo parentTrace : recipeTrace.getParentRecipeTraces()) {
+            getOrCreateNodeByRecipe(parentTrace);
+        }
+    }
+
+    //// Remoting - TODO eliminate?
+
+    synchronized RemoteReceiver accessRemoteReceiver(Address<? extends Supplier> address) {
+        throw new UnsupportedOperationException("Multi-container Rete not supported yet");
+        // if (!reteContainer.isLocal(address))
+        // return
+        // address.getContainer().getProvisioner().accessRemoteReceiver(address);
+        // Supplier localSupplier = reteContainer.resolveLocal(address);
+        // RemoteReceiver result = remoteReceivers.get(localSupplier);
+        // if (result == null) {
+        // result = new RemoteReceiver(reteContainer);
+        // reteContainer.connect(localSupplier, result); // stateless node, no
+        // // synch required
+        //
+        // if (Options.nodeSharingOption != Options.NodeSharingOption.NEVER)
+        // remoteReceivers.put(localSupplier, result);
+        // }
+        // return result;
+    }
+
+    /**
+     * @pre: address is NOT local
+     */
+    synchronized RemoteSupplier accessRemoteSupplier(Address<? extends Supplier> address) {
+        throw new UnsupportedOperationException("Multi-container Rete not supported yet");
+        // RemoteSupplier result = remoteSuppliers.get(address);
+        // if (result == null) {
+        // result = new RemoteSupplier(reteContainer,
+        // address.getContainer().getProvisioner()
+        // .accessRemoteReceiver(address));
+        // // network.connectAndSynchronize(supplier, result);
+        //
+        // if (Options.nodeSharingOption != Options.NodeSharingOption.NEVER)
+        // remoteSuppliers.put(address, result);
+        // }
+        // return result;
+    }
+
+    /**
+     * The powerful method for accessing any (supplier) Address as a local supplier.
+     */
+    public Supplier asSupplier(Address<? extends Supplier> address) {
+        if (!reteContainer.isLocal(address))
+            return accessRemoteSupplier(address);
+        else
+            return reteContainer.resolveLocal(address);
+    }
+
+    /** the composite key tuple is formed as (RecipeTraceInfo, TupleMask) */
+    private Map<Tuple, UserRequestTrace> projectionIndexerUserRequests = CollectionsFactory.createMap();
+
+    // local version
+    // TODO remove?
+    public synchronized ProjectionIndexer accessProjectionIndexer(RecipeTraceInfo productionTrace, TupleMask mask) {
+        Tuple tableKey = Tuples.staticArityFlatTupleOf(productionTrace, mask);
+        UserRequestTrace indexerTrace = projectionIndexerUserRequests.computeIfAbsent(tableKey, k -> {
+            final ProjectionIndexerRecipe projectionIndexerRecipe = projectionIndexerRecipe(
+                    productionTrace, mask);
+            return new UserRequestTrace(projectionIndexerRecipe, productionTrace);
+        });
+        final Address<? extends Node> address = getOrCreateNodeByRecipe(indexerTrace);
+        return (ProjectionIndexer) reteContainer.resolveLocal(address);
+    }
+
+    // local version
+    public synchronized ProjectionIndexer accessProjectionIndexerOnetime(RecipeTraceInfo supplierTrace,
+            TupleMask mask) {
+        if (Options.nodeSharingOption != Options.NodeSharingOption.NEVER)
+            return accessProjectionIndexer(supplierTrace, mask);
+
+        final Address<? extends Node> supplierAddress = getOrCreateNodeByRecipe(supplierTrace);
+        Supplier supplier = (Supplier) reteContainer.resolveLocal(supplierAddress);
+
+        OnetimeIndexer result = new OnetimeIndexer(reteContainer, mask);
+        reteContainer.getDelayedCommandQueue().add(new DelayedConnectCommand(supplier, result, reteContainer));
+
+        return result;
+    }
+
+    // local, read-only version
+    public synchronized ProjectionIndexer peekProjectionIndexer(RecipeTraceInfo supplierTrace, TupleMask mask) {
+        final Address<? extends Node> address = getNodesByRecipe().get(projectionIndexerRecipe(supplierTrace, mask));
+        return address == null ? null : (ProjectionIndexer) reteContainer.resolveLocal(address);
+    }
+
+    private ProjectionIndexerRecipe projectionIndexerRecipe(
+            RecipeTraceInfo parentTrace, TupleMask mask) {
+        final ReteNodeRecipe parentRecipe = parentTrace.getRecipe();
+        Tuple tableKey = Tuples.staticArityFlatTupleOf(parentRecipe, mask);
+        ProjectionIndexerRecipe projectionIndexerRecipe = resultSeedRecipes.computeIfAbsent(tableKey, k ->
+            RecipesHelper.projectionIndexerRecipe(parentRecipe, CompilerHelper.toRecipeMask(mask))
+        );
+        return projectionIndexerRecipe;
+    }
+
+    /** the composite key tuple is formed as (ReteNodeRecipe, TupleMask) */
+    private Map<Tuple, ProjectionIndexerRecipe> resultSeedRecipes = CollectionsFactory.createMap();
+
+    // public synchronized Address<? extends Supplier>
+    // accessValueBinderFilterNode(
+    // Address<? extends Supplier> supplierAddress, int bindingIndex, Object
+    // bindingValue) {
+    // Supplier supplier = asSupplier(supplierAddress);
+    // Object[] paramsArray = { supplier.getNodeId(), bindingIndex, bindingValue
+    // };
+    // Tuple params = new FlatTuple(paramsArray);
+    // ValueBinderFilterNode result = valueBinderFilters.get(params);
+    // if (result == null) {
+    // result = new ValueBinderFilterNode(reteContainer, bindingIndex,
+    // bindingValue);
+    // reteContainer.connect(supplier, result); // stateless node, no synch
+    // // required
+    //
+    // if (Options.nodeSharingOption == Options.NodeSharingOption.ALL)
+    // valueBinderFilters.put(params, result);
+    // }
+    // return reteContainer.makeAddress(result);
+    // }
+
+    /**
+     * Returns a copy of the given indexer that is an active node by itself (created if does not exist). (Convention:
+     * attached with same mask to a transparent node that is attached to parent node.) Node is created if it does not
+     * exist yet.
+     *
+     * @return an identical but active indexer
+     */
+    // TODO rethink traceability
+    RecipeTraceInfo accessActiveIndexer(RecipeTraceInfo inactiveIndexerRecipeTrace) {
+        final RecipeTraceInfo parentRecipeTrace = inactiveIndexerRecipeTrace.getParentRecipeTraces().iterator().next();
+        final ProjectionIndexerRecipe inactiveIndexerRecipe = (ProjectionIndexerRecipe) inactiveIndexerRecipeTrace
+                .getRecipe();
+
+        final TransparentRecipe transparentRecipe = RecipesFactory.eINSTANCE.createTransparentRecipe();
+        transparentRecipe.setParent(parentRecipeTrace.getRecipe());
+        final ActiveNodeConflictTrace transparentRecipeTrace = new ActiveNodeConflictTrace(transparentRecipe,
+                parentRecipeTrace, inactiveIndexerRecipeTrace);
+
+        final ProjectionIndexerRecipe activeIndexerRecipe = RecipesFactory.eINSTANCE
+                .createProjectionIndexerRecipe();
+        activeIndexerRecipe.setParent(transparentRecipe);
+        activeIndexerRecipe.setMask(inactiveIndexerRecipe.getMask());
+        final ActiveNodeConflictTrace activeIndexerRecipeTrace = new ActiveNodeConflictTrace(activeIndexerRecipe,
+                transparentRecipeTrace, inactiveIndexerRecipeTrace);
+
+        return activeIndexerRecipeTrace;
+    }
+
+    // /**
+    // * @param parent
+    // * @return
+    // */
+    // private TransparentNode accessTransparentNodeInternal(Supplier parent) {
+    // nodeFactory.
+    // return null;
+    // }
+
+    // public synchronized void registerSpecializedProjectionIndexer(Node node,
+    // ProjectionIndexer indexer) {
+    // if (Options.nodeSharingOption != Options.NodeSharingOption.NEVER) {
+    // Object[] paramsArray = { node.getNodeId(), indexer.getMask() };
+    // Tuple params = new FlatTuple(paramsArray);
+    // projectionIndexers.put(params, indexer);
+    // }
+    // }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/PosetAwareReceiver.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/PosetAwareReceiver.java
new file mode 100644
index 00000000..1eaa18e7
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/PosetAwareReceiver.java
@@ -0,0 +1,39 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2016, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network;
+
+import tools.refinery.viatra.runtime.matchers.context.IPosetComparator;
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.tuple.TupleMask;
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+
+/**
+ * @author Tamas Szabo
+ * @since 2.0
+ */
+public interface PosetAwareReceiver extends Receiver {
+
+    public TupleMask getCoreMask();
+    
+    public TupleMask getPosetMask();
+    
+    public IPosetComparator getPosetComparator();
+    
+    /**
+     * Updates the receiver with a newly found or lost partial matching also providing information 
+     * whether the update is a monotone change or not. 
+     * 
+     * @param direction the direction of the update
+     * @param update the update tuple 
+     * @param monotone true if the update is monotone, false otherwise
+     * @since 2.4
+     */
+    public void updateWithPosetInfo(Direction direction, Tuple update, boolean monotone);
+    
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/ProductionNode.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/ProductionNode.java
new file mode 100644
index 00000000..211194c0
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/ProductionNode.java
@@ -0,0 +1,28 @@
+/*******************************************************************************
+ * Copyright (c) 2004-2008 Gabor Bergmann and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+
+package tools.refinery.viatra.runtime.rete.network;
+
+import java.util.Map;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+
+/**
+ * Interface intended for nodes containing complete matches.
+ *
+ * @author Gabor Bergmann
+ */
+public interface ProductionNode extends Tunnel, Iterable<Tuple> {
+
+    /**
+     * @return the position mapping of this particular pattern that maps members of the tuple type to their positions
+     */
+    Map<String, Integer> getPosMapping();
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/Receiver.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/Receiver.java
new file mode 100644
index 00000000..3dc9aad7
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/Receiver.java
@@ -0,0 +1,85 @@
+/*******************************************************************************
+ * Copyright (c) 2004-2008 Gabor Bergmann and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+
+package tools.refinery.viatra.runtime.rete.network;
+
+import java.util.Collection;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
+import tools.refinery.viatra.runtime.rete.network.mailbox.Mailbox;
+
+/**
+ * ALL METHODS: FOR INTERNAL USE ONLY; ONLY INVOKE FROM {@link ReteContainer}
+ * 
+ * @author Gabor Bergmann
+ * @noimplement This interface is not intended to be implemented by external clients.
+ */
+public interface Receiver extends Node {
+
+    /**
+     * Updates the receiver with a newly found or lost partial matching.
+     * 
+     * @since 2.4
+     */
+    public void update(final Direction direction, final Tuple updateElement, final Timestamp timestamp);
+
+    /**
+     * Updates the receiver in batch style with a collection of updates. The input collection consists of pairs in the
+     * form (t, c) where t is an update tuple and c is the count. The count can also be negative, and it specifies how
+     * many times the tuple t gets deleted or inserted. The default implementation of this method simply calls
+     * {@link #update(Direction, Tuple, Timestamp)} individually for all updates.
+     * 
+     * @since 2.8
+     */
+    public default void batchUpdate(final Collection<Map.Entry<Tuple, Integer>> updates, final Timestamp timestamp) {
+        for (final Entry<Tuple, Integer> entry : updates) {
+            int count = entry.getValue();
+
+            Direction direction;
+            if (count < 0) {
+                direction = Direction.DELETE;
+                count = -count;
+            } else {
+                direction = Direction.INSERT;
+            }
+
+            for (int i = 0; i < count; i++) {
+                update(direction, entry.getKey(), timestamp);
+            }
+        }
+    }
+
+    /**
+     * Returns the {@link Mailbox} of this receiver.
+     * 
+     * @return the mailbox
+     * @since 2.0
+     */
+    public Mailbox getMailbox();
+
+    /**
+     * appends a parent that will continuously send insert and revoke updates to this supplier
+     */
+    void appendParent(final Supplier supplier);
+
+    /**
+     * removes a parent
+     */
+    void removeParent(final Supplier supplier);
+
+    /**
+     * access active parent
+     */
+    Collection<Supplier> getParents();
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/RederivableNode.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/RederivableNode.java
new file mode 100644
index 00000000..cae78d37
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/RederivableNode.java
@@ -0,0 +1,34 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2016, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network;
+
+/**
+ * A rederivable node can potentially re-derive tuples after the Rete network has finished the delivery of messages.  
+ * 
+ * @author Tamas Szabo
+ * @since 1.6
+ */
+public interface RederivableNode extends Node, IGroupable {
+
+    /**
+     * The method is called by the {@link ReteContainer} to re-derive tuples after the normal messages have been 
+     * delivered and consumed. The re-derivation process may trigger the creation and delivery of further messages 
+     * and further re-derivation rounds.  
+     */
+    public void rederiveOne();
+    
+    /**
+     * Returns true if this node actually runs in DRed mode (not necessarily). 
+     * 
+     * @return true if the node is operating in DRed mode
+     * @since 2.0
+     */
+    public boolean isInDRedMode();
+    
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/ReinitializedNode.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/ReinitializedNode.java
new file mode 100644
index 00000000..09bff29e
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/ReinitializedNode.java
@@ -0,0 +1,14 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package tools.refinery.viatra.runtime.rete.network;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+
+import java.util.Collection;
+
+public interface ReinitializedNode {
+        void reinitializeWith(Collection<Tuple> tuples);
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/ReteContainer.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/ReteContainer.java
new file mode 100644
index 00000000..79e0526d
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/ReteContainer.java
@@ -0,0 +1,729 @@
+/*******************************************************************************
+ * Copyright (c) 2004-2008 Gabor Bergmann and Daniel Varro
+ * Copyright (c) 2023 The Refinery Authors <https://refinery.tools>
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+
+package tools.refinery.viatra.runtime.rete.network;
+
+import org.apache.log4j.Logger;
+import tools.refinery.viatra.runtime.CancellationToken;
+import tools.refinery.viatra.runtime.matchers.context.IQueryBackendContext;
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.util.Clearable;
+import tools.refinery.viatra.runtime.matchers.util.CollectionsFactory;
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+import tools.refinery.viatra.runtime.matchers.util.timeline.Timeline;
+import tools.refinery.viatra.runtime.rete.boundary.InputConnector;
+import tools.refinery.viatra.runtime.rete.matcher.TimelyConfiguration;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationGroup;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationTracker;
+import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
+import tools.refinery.viatra.runtime.rete.network.communication.timeless.TimelessCommunicationTracker;
+import tools.refinery.viatra.runtime.rete.network.communication.timely.TimelyCommunicationTracker;
+import tools.refinery.viatra.runtime.rete.network.delayed.DelayedCommand;
+import tools.refinery.viatra.runtime.rete.network.delayed.DelayedConnectCommand;
+import tools.refinery.viatra.runtime.rete.network.delayed.DelayedDisconnectCommand;
+import tools.refinery.viatra.runtime.rete.remote.Address;
+import tools.refinery.viatra.runtime.rete.single.SingleInputNode;
+import tools.refinery.viatra.runtime.rete.single.TrimmerNode;
+import tools.refinery.viatra.runtime.rete.util.Options;
+
+import java.util.*;
+import java.util.function.Function;
+
+/**
+ * @author Gabor Bergmann
+ *
+ *         Mutexes: externalMessageLock - enlisting messages into and retrieving from the external message queue
+ * @since 2.2
+ */
+public final class ReteContainer {
+
+    protected Thread consumerThread = null;
+    protected boolean killed = false;
+
+    protected Network network;
+
+    protected LinkedList<Clearable> clearables;
+    protected Map<Long, Node> nodesById;
+    protected long nextId = 0;
+
+    protected ConnectionFactory connectionFactory;
+    protected NodeProvisioner nodeProvisioner;
+
+    protected Deque<UpdateMessage> internalMessageQueue = new ArrayDeque<UpdateMessage>();
+    protected/* volatile */Deque<UpdateMessage> externalMessageQueue = new ArrayDeque<UpdateMessage>();
+    protected Object externalMessageLock = new Object();
+    protected Long clock = 1L; // even: steady state, odd: active queue; access
+                               // ONLY with messageQueue locked!
+    protected Map<ReteContainer, Long> terminationCriteria = null;
+    protected final Logger logger;
+    protected final CommunicationTracker tracker;
+
+    protected final IQueryBackendContext backendContext;
+
+    protected Set<DelayedCommand> delayedCommandQueue;
+    protected Set<DelayedCommand> delayedCommandBuffer;
+    protected boolean executingDelayedCommands;
+
+    protected final TimelyConfiguration timelyConfiguration;
+
+        private final CancellationToken cancellationToken;
+
+    /**
+     * @param threaded
+     *            false if operating in a single-threaded environment
+     */
+    public ReteContainer(Network network, boolean threaded) {
+        super();
+        this.network = network;
+        this.backendContext = network.getEngine().getBackendContext();
+        this.timelyConfiguration = network.getEngine().getTimelyConfiguration();
+                cancellationToken = backendContext.getRuntimeContext().getCancellationToken();
+
+        this.delayedCommandQueue = new LinkedHashSet<DelayedCommand>();
+        this.delayedCommandBuffer = new LinkedHashSet<DelayedCommand>();
+        this.executingDelayedCommands = false;
+
+        if (this.isTimelyEvaluation()) {
+            this.tracker = new TimelyCommunicationTracker(this.getTimelyConfiguration());
+        } else {
+            this.tracker = new TimelessCommunicationTracker();
+        }
+
+        this.nodesById = CollectionsFactory.createMap();
+        this.clearables = new LinkedList<Clearable>();
+        this.logger = network.getEngine().getLogger();
+
+        this.connectionFactory = new ConnectionFactory(this);
+        this.nodeProvisioner = new NodeProvisioner(this);
+
+        if (threaded) {
+            this.terminationCriteria = CollectionsFactory.createMap();
+            this.consumerThread = new Thread("Rete thread of " + ReteContainer.super.toString()) {
+                @Override
+                public void run() {
+                    messageConsumptionCycle();
+                }
+            };
+            this.consumerThread.start();
+        }
+    }
+
+    /**
+     * @since 2.4
+     */
+    public boolean isTimelyEvaluation() {
+        return this.timelyConfiguration != null;
+    }
+
+    /**
+     * @since 2.4
+     */
+    public TimelyConfiguration getTimelyConfiguration() {
+        return this.timelyConfiguration;
+    }
+
+    /**
+     * @since 1.6
+     * @return the communication graph of the nodes, incl. message scheduling
+     */
+    public CommunicationTracker getCommunicationTracker() {
+        return tracker;
+    }
+
+    /**
+     * Stops this container. To be called by Network.kill()
+     */
+    public void kill() {
+        killed = true;
+        if (consumerThread != null)
+            consumerThread.interrupt();
+    }
+
+    /**
+     * Establishes connection between a supplier and a receiver node, regardless which container they are in. Assumption
+     * is that this container is the home of the receiver, but it is not strictly necessary.
+     *
+     * @param synchronise
+     *            indicates whether the receiver should be synchronised to the current contents of the supplier
+     */
+    public void connectRemoteNodes(Address<? extends Supplier> supplier, Address<? extends Receiver> receiver,
+            boolean synchronise) {
+        if (!isLocal(receiver))
+            receiver.getContainer().connectRemoteNodes(supplier, receiver, synchronise);
+        else {
+            Receiver child = resolveLocal(receiver);
+            connectRemoteSupplier(supplier, child, synchronise);
+        }
+    }
+
+    /**
+     * Severs connection between a supplier and a receiver node, regardless which container they are in. Assumption is
+     * that this container is the home of the receiver, but it is not strictly necessary.
+     *
+     * @param desynchronise
+     *            indicates whether the current contents of the supplier should be subtracted from the receiver
+     */
+    public void disconnectRemoteNodes(Address<? extends Supplier> supplier, Address<? extends Receiver> receiver,
+            boolean desynchronise) {
+        if (!isLocal(receiver))
+            receiver.getContainer().disconnectRemoteNodes(supplier, receiver, desynchronise);
+        else {
+            Receiver child = resolveLocal(receiver);
+            disconnectRemoteSupplier(supplier, child, desynchronise);
+        }
+    }
+
+    /**
+     * Establishes connection between a remote supplier and a local receiver node.
+     *
+     * @param synchronise
+     *            indicates whether the receiver should be synchronised to the current contents of the supplier
+     */
+    public void connectRemoteSupplier(Address<? extends Supplier> supplier, Receiver receiver, boolean synchronise) {
+        Supplier parent = nodeProvisioner.asSupplier(supplier);
+        if (synchronise)
+            connectAndSynchronize(parent, receiver);
+        else
+            connect(parent, receiver);
+    }
+
+    /**
+     * Severs connection between a remote supplier and a local receiver node.
+     *
+     * @param desynchronise
+     *            indicates whether the current contents of the supplier should be subtracted from the receiver
+     */
+    public void disconnectRemoteSupplier(Address<? extends Supplier> supplier, Receiver receiver,
+            boolean desynchronise) {
+        Supplier parent = nodeProvisioner.asSupplier(supplier);
+        if (desynchronise)
+            disconnectAndDesynchronize(parent, receiver);
+        else
+            disconnect(parent, receiver);
+    }
+
+    /**
+     * Connects a receiver to a supplier
+     */
+    public void connect(Supplier supplier, Receiver receiver) {
+        supplier.appendChild(receiver);
+        receiver.appendParent(supplier);
+        tracker.registerDependency(supplier, receiver);
+    }
+
+    /**
+     * Disconnects a receiver from a supplier
+     */
+    public void disconnect(Supplier supplier, Receiver receiver) {
+        supplier.removeChild(receiver);
+        receiver.removeParent(supplier);
+        tracker.unregisterDependency(supplier, receiver);
+    }
+
+    /**
+     * @since 2.3
+     */
+    public boolean isExecutingDelayedCommands() {
+        return this.executingDelayedCommands;
+    }
+
+    /**
+     * @since 2.3
+     */
+    public Set<DelayedCommand> getDelayedCommandQueue() {
+        if (this.executingDelayedCommands) {
+            return this.delayedCommandBuffer;
+        } else {
+            return this.delayedCommandQueue;
+        }
+    }
+
+    /**
+     * Connects a receiver to a remote supplier, and synchronizes it to the current contents of the supplier
+     */
+    public void connectAndSynchronize(Supplier supplier, Receiver receiver) {
+        supplier.appendChild(receiver);
+        receiver.appendParent(supplier);
+        tracker.registerDependency(supplier, receiver);
+        getDelayedCommandQueue().add(new DelayedConnectCommand(supplier, receiver, this));
+    }
+
+    /**
+     * Disconnects a receiver from a supplier
+     */
+    public void disconnectAndDesynchronize(Supplier supplier, Receiver receiver) {
+        final boolean wasInSameSCC = this.isTimelyEvaluation() && this.tracker.areInSameGroup(supplier, receiver);
+        supplier.removeChild(receiver);
+        receiver.removeParent(supplier);
+        tracker.unregisterDependency(supplier, receiver);
+        getDelayedCommandQueue().add(new DelayedDisconnectCommand(supplier, receiver, this, wasInSameSCC));
+    }
+
+    /**
+     * @since 2.3
+     */
+    public void executeDelayedCommands() {
+        if (!this.delayedCommandQueue.isEmpty()) {
+            flushUpdates();
+            this.executingDelayedCommands = true;
+            for (final DelayedCommand command : this.delayedCommandQueue) {
+                command.run();
+            }
+            this.delayedCommandQueue = this.delayedCommandBuffer;
+            this.delayedCommandBuffer = new LinkedHashSet<DelayedCommand>();
+            flushUpdates();
+            this.executingDelayedCommands = false;
+        }
+    }
+
+    /**
+     * Sends an update message to the receiver node, indicating a newly found or lost partial matching. The receiver is
+     * indicated by the Address. Designed to be called by the Network, DO NOT use in any other way. @pre:
+     * address.container == this, e.g. address MUST be local
+     *
+     * @return the value of the container's clock at the time when the message was accepted into the local message queue
+     */
+    long sendUpdateToLocalAddress(Address<? extends Receiver> address, Direction direction, Tuple updateElement) {
+        long timestamp;
+        Receiver receiver = resolveLocal(address);
+        UpdateMessage message = new UpdateMessage(receiver, direction, updateElement);
+        synchronized (externalMessageLock) {
+            externalMessageQueue.add(message);
+            timestamp = clock;
+            externalMessageLock.notifyAll();
+        }
+
+        return timestamp;
+
+    }
+
+    /**
+     * Sends multiple update messages atomically to the receiver node, indicating a newly found or lost partial
+     * matching. The receiver is indicated by the Address. Designed to be called by the Network, DO NOT use in any other
+     * way. @pre: address.container == this, e.g. address MUST be local @pre: updateElements is nonempty!
+     *
+     * @return the value of the container's clock at the time when the message was accepted into the local message queue
+     */
+    long sendUpdatesToLocalAddress(Address<? extends Receiver> address, Direction direction,
+            Collection<Tuple> updateElements) {
+
+        long timestamp;
+        Receiver receiver = resolveLocal(address);
+        // UpdateMessage message = new UpdateMessage(receiver, direction,
+        // updateElement);
+        synchronized (externalMessageLock) {
+            for (Tuple ps : updateElements)
+                externalMessageQueue.add(new UpdateMessage(receiver, direction, ps));
+            // messageQueue.add(new UpdateMessage(resolveLocal(address),
+            // direction, updateElement));
+            // this.sendUpdateInternal(resolveLocal(address), direction,
+            // updateElement);
+            timestamp = clock;
+            externalMessageLock.notifyAll();
+        }
+
+        return timestamp;
+    }
+
+    /**
+     * Sends an update message to the receiver node, indicating a newly found or lost partial matching. The receiver is
+     * indicated by the Address. Designed to be called by the Network in single-threaded operation, DO NOT use in any
+     * other way.
+     */
+    void sendUpdateToLocalAddressSingleThreaded(Address<? extends Receiver> address, Direction direction,
+            Tuple updateElement) {
+        Receiver receiver = resolveLocal(address);
+        UpdateMessage message = new UpdateMessage(receiver, direction, updateElement);
+        internalMessageQueue.add(message);
+    }
+
+    /**
+     * Sends multiple update messages to the receiver node, indicating a newly found or lost partial matching. The
+     * receiver is indicated by the Address. Designed to be called by the Network in single-threaded operation, DO NOT
+     * use in any other way.
+     *
+     * @pre: address.container == this, e.g. address MUST be local
+     */
+    void sendUpdatesToLocalAddressSingleThreaded(Address<? extends Receiver> address, Direction direction,
+            Collection<Tuple> updateElements) {
+        Receiver receiver = resolveLocal(address);
+        for (Tuple ps : updateElements)
+            internalMessageQueue.add(new UpdateMessage(receiver, direction, ps));
+    }
+
+    /**
+     * Sends an update message to a node in a different container. The receiver is indicated by the Address. Designed to
+     * be called by RemoteReceivers, DO NOT use in any other way.
+     *
+     * @since 2.4
+     */
+    public void sendUpdateToRemoteAddress(Address<? extends Receiver> address, Direction direction,
+            Tuple updateElement) {
+        ReteContainer otherContainer = address.getContainer();
+        long otherClock = otherContainer.sendUpdateToLocalAddress(address, direction, updateElement);
+        // Long criterion = terminationCriteria.get(otherContainer);
+        // if (criterion==null || otherClock > criterion)
+        terminationCriteria.put(otherContainer, otherClock);
+    }
+
+    /**
+     * Finalises all update sequences and returns. To be called from user threads (e.g. network construction).
+     */
+    public void flushUpdates() {
+        network.waitForReteTermination();
+        // synchronized (messageQueue)
+        // {
+        // while (!messageQueue.isEmpty())
+        // {
+        // try {
+        // UpdateMessage message = messageQueue.take();
+        // message.receiver.update(message.direction, message.updateElement);
+        // } catch (InterruptedException e) {}
+        // }
+        // }
+    }
+
+    /**
+     * Retrieves a safe copy of the contents of a supplier.
+     *
+     * <p> Note that there may be multiple copies of a Tuple in case of a {@link TrimmerNode}, so the result is not always a set.
+     *
+     * @param flush if true, a flush is performed before pulling the contents
+     * @since 2.3
+     */
+    public Collection<Tuple> pullContents(final Supplier supplier, final boolean flush) {
+        if (flush) {
+            flushUpdates();
+        }
+        final Collection<Tuple> collector = new ArrayList<Tuple>();
+        supplier.pullInto(collector, flush);
+        return collector;
+    }
+
+    /**
+     * @since 2.4
+     */
+    public Map<Tuple, Timeline<Timestamp>> pullContentsWithTimeline(final Supplier supplier, final boolean flush) {
+        if (flush) {
+            flushUpdates();
+        }
+        final Map<Tuple, Timeline<Timestamp>> collector = CollectionsFactory.createMap();
+        supplier.pullIntoWithTimeline(collector, flush);
+        return collector;
+    }
+
+    /**
+     * Retrieves the contents of a SingleInputNode's parentage.
+     *
+     * @since 2.3
+     */
+    public Collection<Tuple> pullPropagatedContents(final SingleInputNode supplier, final boolean flush) {
+        if (flush) {
+            flushUpdates();
+        }
+        final Collection<Tuple> collector = new LinkedList<Tuple>();
+        supplier.propagatePullInto(collector, flush);
+        return collector;
+    }
+
+    /**
+     * Retrieves the timestamp-aware contents of a SingleInputNode's parentage.
+     *
+     * @since 2.3
+     */
+    public Map<Tuple, Timeline<Timestamp>> pullPropagatedContentsWithTimestamp(final SingleInputNode supplier,
+            final boolean flush) {
+        if (flush) {
+            flushUpdates();
+        }
+        final Map<Tuple, Timeline<Timestamp>> collector = CollectionsFactory.createMap();
+        supplier.propagatePullIntoWithTimestamp(collector, flush);
+        return collector;
+    }
+
+    /**
+     * Retrieves the contents of a supplier for a remote caller. Assumption is that this container is the home of the
+     * supplier, but it is not strictly necessary.
+     *
+     * @param supplier
+     *            the address of the supplier to be pulled.
+     * @since 2.3
+     */
+    public Collection<Tuple> remotePull(Address<? extends Supplier> supplier, boolean flush) {
+        if (!isLocal(supplier))
+            return supplier.getContainer().remotePull(supplier, flush);
+        return pullContents(resolveLocal(supplier), flush);
+    }
+
+    /**
+     * Proxies for the getPosMapping() of Production nodes. Retrieves the posmapping of a remote or local Production to
+     * a remote or local caller.
+     */
+    public Map<String, Integer> remotePosMapping(Address<? extends ProductionNode> production) {
+        if (!isLocal(production))
+            return production.getContainer().remotePosMapping(production);
+        return resolveLocal(production).getPosMapping();
+    }
+
+    /**
+     * Continually consumes update messages. Should be run on a dedicated thread.
+     */
+    void messageConsumptionCycle() {
+        while (!killed) // deliver messages on and on and on....
+        {
+            long incrementedClock = 0;
+            UpdateMessage message = null;
+
+            if (!internalMessageQueue.isEmpty()) // take internal messages first
+                message = internalMessageQueue.removeFirst();
+            else
+                // no internal message, take an incoming message
+                synchronized (externalMessageLock) { // no sleeping allowed,
+                                                     // because external
+                                                     // queue is locked for
+                                                     // precise clocking of
+                                                     // termination point!
+                    if (!externalMessageQueue.isEmpty()) { // if external queue
+                                                           // is non-empty,
+                                                           // retrieve the next
+                                                           // message instantly
+                        message = takeExternalMessage();
+                    } else { // if external queue is found empty (and this is
+                             // the first time in a row)
+                        incrementedClock = ++clock; // local termination point
+                        // synchronized(clock){incrementedClock = ++clock;}
+                    }
+                }
+
+            if (message == null) // both queues were empty
+            {
+                localUpdateTermination(incrementedClock); // report local
+                                                          // termination point
+                while (message == null) // wait for a message while external
+                                        // queue is still empty
+                {
+                    synchronized (externalMessageLock) {
+                        while (externalMessageQueue.isEmpty()) {
+                            try {
+                                externalMessageLock.wait();
+                            } catch (InterruptedException e) {
+                                if (killed)
+                                    return;
+                            }
+                        }
+                        message = takeExternalMessage();
+                    }
+
+                }
+            }
+
+            // now we have a message to deliver
+            // NOTE: this method is not compatible with differential dataflow
+            message.receiver.update(message.direction, message.updateElement, Timestamp.ZERO);
+        }
+    }
+
+    /**
+     * @since 1.6
+     */
+    public static final Function<Node, String> NAME_MAPPER = input -> input.toString().substring(0,
+            Math.min(30, input.toString().length()));
+
+    /**
+     * Sends out all pending messages to their receivers. The delivery is governed by the communication tracker.
+     *
+     * @since 1.6
+     */
+    public void deliverMessagesSingleThreaded() {
+        if (!backendContext.areUpdatesDelayed()) {
+            if (Options.MONITOR_VIOLATION_OF_RETE_NODEGROUP_TOPOLOGICAL_SORTING) {
+                // known unreachable; enable for debugging only
+
+                CommunicationGroup lastGroup = null;
+                Set<CommunicationGroup> seenInThisCycle = new HashSet<>();
+
+                while (!tracker.isEmpty()) {
+                    final CommunicationGroup group = tracker.getAndRemoveFirstGroup();
+
+                    /**
+                     * The current group does not violate the communication schema iff (1) it was not seen before OR (2)
+                     * the last one that was seen is exactly the same as the current one this can happen if the group
+                     * was added back because of in-group message passing
+                     */
+                    boolean okGroup = (group == lastGroup) || seenInThisCycle.add(group);
+
+                    if (!okGroup) {
+                        logger.error(
+                                "[INTERNAL ERROR] Violation of communication schema! The communication component with representative "
+                                        + group.getRepresentative() + " has already been processed!");
+                    }
+
+                    group.deliverMessages();
+
+                    lastGroup = group;
+                }
+
+            } else {
+                while (!tracker.isEmpty()) {
+                    final CommunicationGroup group = tracker.getAndRemoveFirstGroup();
+                    group.deliverMessages();
+                }
+            }
+        }
+    }
+
+    private void localUpdateTermination(long incrementedClock) {
+        network.reportLocalUpdateTermination(this, incrementedClock, terminationCriteria);
+        terminationCriteria.clear();
+
+        // synchronized(clock){++clock;} // +1 incrementing for parity and easy
+        // comparison
+    }
+
+    // @pre: externalMessageQueue synchronized && nonempty
+    private UpdateMessage takeExternalMessage() {
+        UpdateMessage message = externalMessageQueue.removeFirst();
+        if (!externalMessageQueue.isEmpty()) { // copy the whole queue over
+                                               // for speedup
+            Deque<UpdateMessage> temp = externalMessageQueue;
+            externalMessageQueue = internalMessageQueue;
+            internalMessageQueue = temp;
+        }
+        return message;
+    }
+
+    /**
+     * Provides an external address for the selected node.
+     *
+     * @pre node belongs to this container.
+     */
+    public <N extends Node> Address<N> makeAddress(N node) {
+        return new Address<N>(node);
+    }
+
+    /**
+     * Checks whether a certain address points to a node at this container.
+     */
+    public boolean isLocal(Address<? extends Node> address) {
+        return address.getContainer() == this;
+    }
+
+    /**
+     * Returns an addressed node at this container.
+     *
+     * @pre: address.container == this, e.g. address MUST be local
+     * @throws IllegalArgumentException
+     *             if address is non-local
+     */
+    @SuppressWarnings("unchecked")
+    public <N extends Node> N resolveLocal(Address<N> address) {
+        if (this != address.getContainer())
+            throw new IllegalArgumentException(String.format("Address %s non-local at container %s", address, this));
+
+        N cached = address.getNodeCache();
+        if (cached != null)
+            return cached;
+        else {
+            N node = (N) nodesById.get(address.getNodeId());
+            address.setNodeCache(node);
+            return node;
+        }
+    }
+
+    /**
+     * Registers a node into the rete network (should be called by constructor). Every node MUST be registered by its
+     * constructor.
+     *
+     * @return the unique nodeId issued to the node.
+     */
+    public long registerNode(Node n) {
+        long id = nextId++;
+        nodesById.put(id, n);
+        return id;
+    }
+
+    /**
+     * Unregisters a node from the rete network. Do NOT call if node is still connected to other Nodes, or Adressed or
+     * otherwise referenced.
+     */
+    public void unregisterNode(Node n) {
+        nodesById.remove(n.getNodeId());
+    }
+
+    /**
+     * Registers a pattern memory into the rete network. Every memory MUST be registered by its owner node.
+     */
+    public void registerClearable(Clearable c) {
+        clearables.addFirst(c);
+    }
+
+    /**
+     * Unregisters a pattern memory from the rete network.
+     */
+    public void unregisterClearable(Clearable c) {
+        clearables.remove(c);
+    }
+
+    /**
+     * Clears all memory contents in the network. Reverts to initial state.
+     */
+    public void clearAll() {
+        for (Clearable c : clearables) {
+            c.clear();
+        }
+    }
+
+    public NodeFactory getNodeFactory() {
+        return network.getNodeFactory();
+    }
+
+    public ConnectionFactory getConnectionFactory() {
+        return connectionFactory;
+    }
+
+    public NodeProvisioner getProvisioner() {
+        return nodeProvisioner;
+    }
+
+    public Network getNetwork() {
+        return network;
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder();
+        String separator = System.getProperty("line.separator");
+        sb.append(super.toString() + "[[[" + separator);
+        java.util.List<Long> keys = new java.util.ArrayList<Long>(nodesById.keySet());
+        java.util.Collections.sort(keys);
+        for (Long key : keys) {
+            sb.append(key + " -> " + nodesById.get(key) + separator);
+        }
+        sb.append("]]] of " + network);
+        return sb.toString();
+    }
+
+    /**
+     * Access all the Rete nodes inside this container.
+     *
+     * @return the collection of {@link Node} instances
+     */
+    public Collection<Node> getAllNodes() {
+        return nodesById.values();
+    }
+
+    public InputConnector getInputConnectionFactory() {
+        return network.getInputConnector();
+    }
+
+        public void checkCancelled() {
+                cancellationToken.checkCancelled();
+        }
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/StandardNode.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/StandardNode.java
new file mode 100644
index 00000000..7dc7c4bc
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/StandardNode.java
@@ -0,0 +1,123 @@
+/*******************************************************************************
+ * Copyright (c) 2004-2008 Gabor Bergmann and Daniel Varro
+ * Copyright (c) 2023 The Refinery Authors <https://refinery.tools>
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+
+package tools.refinery.viatra.runtime.rete.network;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.tuple.TupleMask;
+import tools.refinery.viatra.runtime.matchers.util.CollectionsFactory;
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+import tools.refinery.viatra.runtime.rete.index.GenericProjectionIndexer;
+import tools.refinery.viatra.runtime.rete.index.ProjectionIndexer;
+import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
+import tools.refinery.viatra.runtime.rete.network.mailbox.Mailbox;
+import tools.refinery.viatra.runtime.rete.traceability.TraceInfo;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * Base implementation for a supplier node.
+ *
+ * @author Gabor Bergmann
+ *
+ */
+public abstract class StandardNode extends BaseNode implements Supplier, NetworkStructureChangeSensitiveNode {
+    protected final List<Receiver> children = CollectionsFactory.createObserverList();
+    /**
+     * @since 2.2
+     */
+    protected final List<Mailbox> childMailboxes = CollectionsFactory.createObserverList();
+
+    public StandardNode(final ReteContainer reteContainer) {
+        super(reteContainer);
+    }
+
+    /**
+     * @since 2.4
+     */
+    protected void propagateUpdate(final Direction direction, final Tuple updateElement, final Timestamp timestamp) {
+                reteContainer.checkCancelled();
+        for (final Mailbox childMailbox : childMailboxes) {
+            childMailbox.postMessage(direction, updateElement, timestamp);
+        }
+    }
+
+    @Override
+    public void appendChild(final Receiver receiver) {
+        children.add(receiver);
+        childMailboxes.add(this.getCommunicationTracker().proxifyMailbox(this, receiver.getMailbox()));
+    }
+
+    @Override
+    public void removeChild(final Receiver receiver) {
+        children.remove(receiver);
+        Mailbox mailboxToRemove = null;
+        for (final Mailbox mailbox : childMailboxes) {
+            if (mailbox.getReceiver() == receiver) {
+                mailboxToRemove = mailbox;
+                break;
+            }
+        }
+        assert mailboxToRemove != null;
+        childMailboxes.remove(mailboxToRemove);
+    }
+
+    @Override
+    public void networkStructureChanged() {
+        childMailboxes.clear();
+        for (final Receiver receiver : children) {
+            childMailboxes.add(this.getCommunicationTracker().proxifyMailbox(this, receiver.getMailbox()));
+        }
+    }
+
+    @Override
+    public Collection<Receiver> getReceivers() {
+        return children;
+    }
+
+    /**
+     * @since 2.2
+     */
+    public Collection<Mailbox> getChildMailboxes() {
+        return this.childMailboxes;
+    }
+
+    @Override
+    public Set<Tuple> getPulledContents(final boolean flush) {
+        final HashSet<Tuple> results = new HashSet<Tuple>();
+        pullInto(results, flush);
+        return results;
+    }
+
+    @Override
+    public ProjectionIndexer constructIndex(final TupleMask mask, final TraceInfo... traces) {
+        final GenericProjectionIndexer indexer = new GenericProjectionIndexer(reteContainer, mask);
+        for (final TraceInfo traceInfo : traces) {
+            indexer.assignTraceInfo(traceInfo);
+        }
+        reteContainer.connectAndSynchronize(this, indexer);
+        return indexer;
+    }
+
+    /**
+     * @since 1.6
+     */
+    protected void issueError(final String message, final Exception ex) {
+        if (ex == null) {
+            this.reteContainer.getNetwork().getEngine().getLogger().error(message);
+        } else {
+            this.reteContainer.getNetwork().getEngine().getLogger().error(message, ex);
+        }
+    }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/Supplier.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/Supplier.java
new file mode 100644
index 00000000..1917a7cf
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/Supplier.java
@@ -0,0 +1,82 @@
+/*******************************************************************************
+ * Copyright (c) 2004-2008 Gabor Bergmann and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+
+package tools.refinery.viatra.runtime.rete.network;
+
+import java.util.Collection;
+import java.util.Map;
+import java.util.Set;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.tuple.TupleMask;
+import tools.refinery.viatra.runtime.matchers.util.timeline.Timeline;
+import tools.refinery.viatra.runtime.rete.index.ProjectionIndexer;
+import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
+import tools.refinery.viatra.runtime.rete.single.TrimmerNode;
+import tools.refinery.viatra.runtime.rete.traceability.TraceInfo;
+
+/**
+ * @author Gabor Bergmann
+ * 
+ *         A supplier is an object that can propagate insert or revoke events towards receivers.
+ */
+public interface Supplier extends Node {
+
+    /**
+     * Pulls the contents of this object in this particular moment into a target collection. 
+     * 
+     * @param flush if true, flushing of messages is allowed during the pull, otherwise flushing is not allowed
+     * @since 2.3
+     */
+    public void pullInto(Collection<Tuple> collector, boolean flush);
+    
+    /**
+     * @since 2.4
+     */
+    public void pullIntoWithTimeline(final Map<Tuple, Timeline<Timestamp>> collector, final boolean flush);
+    
+    /**
+     * Returns the contents of this object in this particular moment. 
+     * For memoryless nodes, this may involve a costly recomputation of contents.
+     * 
+     * The result is returned as a Set, even when it has multiplicities (at the output of {@link TrimmerNode}).
+     * 
+     *  <p> Intended mainly for debug purposes; therefore flushing is performed only if explicitly requested
+     *  During runtime, flushing may be preferred; see {@link ReteContainer#pullContents(Supplier)}
+     * @since 2.3
+     */
+    public Set<Tuple> getPulledContents(boolean flush);
+    
+    default public Set<Tuple> getPulledContents() {
+        return getPulledContents(true);
+    }
+
+    /**
+     * appends a receiver that will continously receive insert and revoke updates from this supplier
+     */
+    void appendChild(Receiver receiver);
+
+    /**
+     * removes a receiver
+     */
+    void removeChild(Receiver receiver);
+
+    /**
+     * Instantiates (or reuses, depending on implementation) an index according to the given mask. 
+     * 
+     * Intended for internal use; clients should invoke through Library instead to enable reusing.
+     */
+    ProjectionIndexer constructIndex(TupleMask mask, TraceInfo... traces);
+
+    /**
+     * lists receivers
+     */
+    Collection<Receiver> getReceivers();
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/Tunnel.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/Tunnel.java
new file mode 100644
index 00000000..f238f47b
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/Tunnel.java
@@ -0,0 +1,19 @@
+/*******************************************************************************
+ * Copyright (c) 2004-2008 Gabor Bergmann and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+
+package tools.refinery.viatra.runtime.rete.network;
+
+/**
+ * @author Gabor Bergmann
+ * 
+ *         A Tunnel is an interface into which elments can be instered and from which productions can be extracted.
+ */
+public interface Tunnel extends Supplier, Receiver {
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/UpdateMessage.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/UpdateMessage.java
new file mode 100644
index 00000000..1334a3a9
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/UpdateMessage.java
@@ -0,0 +1,31 @@
+/*******************************************************************************
+ * Copyright (c) 2004-2008 Gabor Bergmann and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+
+package tools.refinery.viatra.runtime.rete.network;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+
+class UpdateMessage {
+    public Receiver receiver;
+    public Direction direction;
+    public Tuple updateElement;
+
+    public UpdateMessage(Receiver receiver, Direction direction, Tuple updateElement) {
+        this.receiver = receiver;
+        this.direction = direction;
+        this.updateElement = updateElement;
+    }
+
+    @Override
+    public String toString() {
+        return "M." + direction + ": " + updateElement + " -> " + receiver;
+    }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/CommunicationGroup.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/CommunicationGroup.java
new file mode 100644
index 00000000..8cedeb11
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/CommunicationGroup.java
@@ -0,0 +1,103 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2017, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.communication;
+
+import java.util.Collection;
+import java.util.Map;
+
+import tools.refinery.viatra.runtime.rete.network.Node;
+import tools.refinery.viatra.runtime.rete.network.mailbox.Mailbox;
+
+/**
+ * A communication group represents a set of nodes in the communication graph that form a strongly connected component.
+ * 
+ * @author Tamas Szabo
+ * @since 1.6
+ */
+public abstract class CommunicationGroup implements Comparable<CommunicationGroup> {
+
+    public static final String UNSUPPORTED_MESSAGE_KIND = "Unsupported message kind ";
+
+    /**
+     * Marker for the {@link CommunicationTracker}
+     */
+    public boolean isEnqueued = false;
+
+    protected final Node representative;
+
+    /**
+     * May be changed during bumping in {@link CommunicationTracker.registerDependency}
+     */
+    protected int identifier;
+
+    /**
+     * @since 1.7
+     */
+    protected final CommunicationTracker tracker;
+
+    /**
+     * @since 1.7
+     */
+    public CommunicationGroup(final CommunicationTracker tracker, final Node representative, final int identifier) {
+        this.tracker = tracker;
+        this.representative = representative;
+        this.identifier = identifier;
+    }
+
+    public abstract void deliverMessages();
+
+    public Node getRepresentative() {
+        return representative;
+    }
+
+    public abstract boolean isEmpty();
+
+    /**
+     * @since 2.0
+     */
+    public abstract void notifyLostAllMessages(final Mailbox mailbox, final MessageSelector kind);
+
+    /**
+     * @since 2.0
+     */
+    public abstract void notifyHasMessage(final Mailbox mailbox, final MessageSelector kind);
+
+    public abstract Map<MessageSelector, Collection<Mailbox>> getMailboxes();
+
+    public abstract boolean isRecursive();
+
+    @Override
+    public int hashCode() {
+        return this.identifier;
+    }
+
+    @Override
+    public String toString() {
+        return this.getClass().getSimpleName() + " " + this.identifier + " - representative: " + this.representative
+                + " - isEmpty: " + isEmpty();
+    }
+
+    @Override
+    public boolean equals(final Object obj) {
+        if (obj == null || this.getClass() != obj.getClass()) {
+            return false;
+        } else if (this == obj) {
+            return true;
+        } else {
+            final CommunicationGroup that = (CommunicationGroup) obj;
+            return this.identifier == that.identifier;
+        }
+    }
+
+    @Override
+    public int compareTo(final CommunicationGroup that) {
+        return this.identifier - that.identifier;
+    }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/CommunicationTracker.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/CommunicationTracker.java
new file mode 100644
index 00000000..d244e644
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/CommunicationTracker.java
@@ -0,0 +1,467 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2017, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.communication;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.PriorityQueue;
+import java.util.Queue;
+import java.util.Set;
+
+import tools.refinery.viatra.runtime.rete.itc.alg.incscc.IncSCCAlg;
+import tools.refinery.viatra.runtime.rete.itc.alg.misc.topsort.TopologicalSorting;
+import tools.refinery.viatra.runtime.rete.itc.graphimpl.Graph;
+import tools.refinery.viatra.runtime.matchers.tuple.TupleMask;
+import tools.refinery.viatra.runtime.rete.aggregation.IAggregatorNode;
+import tools.refinery.viatra.runtime.rete.boundary.ExternalInputEnumeratorNode;
+import tools.refinery.viatra.runtime.rete.eval.RelationEvaluatorNode;
+import tools.refinery.viatra.runtime.rete.index.DualInputNode;
+import tools.refinery.viatra.runtime.rete.index.ExistenceNode;
+import tools.refinery.viatra.runtime.rete.index.Indexer;
+import tools.refinery.viatra.runtime.rete.index.IndexerListener;
+import tools.refinery.viatra.runtime.rete.index.IterableIndexer;
+import tools.refinery.viatra.runtime.rete.index.SpecializedProjectionIndexer;
+import tools.refinery.viatra.runtime.rete.network.IGroupable;
+import tools.refinery.viatra.runtime.rete.network.NetworkStructureChangeSensitiveNode;
+import tools.refinery.viatra.runtime.rete.network.Node;
+import tools.refinery.viatra.runtime.rete.network.ProductionNode;
+import tools.refinery.viatra.runtime.rete.network.Receiver;
+import tools.refinery.viatra.runtime.rete.network.ReteContainer;
+import tools.refinery.viatra.runtime.rete.network.communication.timely.TimelyIndexerListenerProxy;
+import tools.refinery.viatra.runtime.rete.network.communication.timely.TimelyMailboxProxy;
+import tools.refinery.viatra.runtime.rete.network.mailbox.FallThroughCapableMailbox;
+import tools.refinery.viatra.runtime.rete.network.mailbox.Mailbox;
+import tools.refinery.viatra.runtime.rete.network.mailbox.timeless.BehaviorChangingMailbox;
+import tools.refinery.viatra.runtime.rete.single.TransitiveClosureNode;
+import tools.refinery.viatra.runtime.rete.single.TrimmerNode;
+
+/**
+ * An instance of this class is associated with every {@link ReteContainer}. The tracker serves two purposes: <br>
+ * (1) It allows RETE nodes to register their communication dependencies on-the-fly. These dependencies can be
+ * registered or unregistered when nodes are disposed of. <br>
+ * (2) It allows RETE nodes to register their mailboxes as dirty, that is, they can tell the tracker that they have
+ * something to send to other nodes in the network. The tracker is then responsible for ordering these messages (more
+ * precisely, the mailboxes that contain the messages) for the associated {@link ReteContainer}. The ordering is
+ * governed by the strongly connected components in the dependency network and follows a topological sorting scheme;
+ * those mailboxes will be emptied first whose owner nodes do not depend on other undelivered messages.
+ *
+ * @author Tamas Szabo
+ * @since 1.6
+ *
+ */
+public abstract class CommunicationTracker {
+
+    /**
+     * The minimum group id assigned so far
+     */
+    protected int minGroupId;
+
+    /**
+     * The maximum group id assigned so far
+     */
+    protected int maxGroupId;
+
+    /**
+     * The dependency graph of the communications in the RETE network
+     */
+    protected final Graph<Node> dependencyGraph;
+
+    /**
+     * Incremental SCC information about the dependency graph
+     */
+    protected final IncSCCAlg<Node> sccInformationProvider;
+
+    /**
+     * Precomputed node -> communication group map
+     */
+    protected final Map<Node, CommunicationGroup> groupMap;
+
+    /**
+     * Priority queue of active communication groups
+     */
+    protected final Queue<CommunicationGroup> groupQueue;
+
+    // groups should have a simple integer flag which represents its position in a priority queue
+    // priority queue only contains the ACTIVE groups
+
+    public CommunicationTracker() {
+        this.dependencyGraph = new Graph<Node>();
+        this.sccInformationProvider = new IncSCCAlg<Node>(this.dependencyGraph);
+        this.groupQueue = new PriorityQueue<CommunicationGroup>();
+        this.groupMap = new HashMap<Node, CommunicationGroup>();
+    }
+
+    public Graph<Node> getDependencyGraph() {
+        return dependencyGraph;
+    }
+
+    public CommunicationGroup getGroup(final Node node) {
+        return this.groupMap.get(node);
+    }
+
+    private void precomputeGroups() {
+        groupMap.clear();
+
+        // reconstruct group map from dependency graph
+        final Graph<Node> reducedGraph = sccInformationProvider.getReducedGraph();
+        final List<Node> representatives = TopologicalSorting.compute(reducedGraph);
+
+        for (int i = 0; i < representatives.size(); i++) { // groups for SCC representatives
+            final Node representative = representatives.get(i);
+            createAndStoreGroup(representative, i);
+        }
+
+        minGroupId = 0;
+        maxGroupId = representatives.size() - 1;
+
+        for (final Node node : dependencyGraph.getAllNodes()) { // extend group map to the rest of nodes
+            final Node representative = sccInformationProvider.getRepresentative(node);
+            final CommunicationGroup group = groupMap.get(representative);
+            if (representative != node) {
+                addToGroup(node, group);
+            }
+        }
+
+        for (final Node node : dependencyGraph.getAllNodes()) {
+            // set fall-through flags of default mailboxes
+            precomputeFallThroughFlag(node);
+            // perform further tracker-specific post-processing
+            postProcessNode(node);
+        }
+
+        // reconstruct new queue contents based on new group map
+        if (!groupQueue.isEmpty()) {
+            final Set<CommunicationGroup> oldActiveGroups = new HashSet<CommunicationGroup>(groupQueue);
+            groupQueue.clear();
+            reconstructQueueContents(oldActiveGroups);
+        }
+
+        // post process the groups
+        for (final CommunicationGroup group : groupMap.values()) {
+            postProcessGroup(group);
+        }
+    }
+
+    /**
+     * This method is responsible for reconstructing the active queue contents after the network structure has changed.
+     * It it defined as abstract because the reconstruction logic is specific to each {@link CommunicationTracker}.
+     * @since 2.4
+     */
+    protected abstract void reconstructQueueContents(final Set<CommunicationGroup> oldActiveGroups);
+
+    private void addToGroup(final Node node, final CommunicationGroup group) {
+        groupMap.put(node, group);
+        if (node instanceof Receiver) {
+            ((Receiver) node).getMailbox().setCurrentGroup(group);
+            if (node instanceof IGroupable) {
+                ((IGroupable) node).setCurrentGroup(group);
+            }
+        }
+    }
+
+    /**
+     * Depends on the groups, as well as the parent nodes of the argument, so recomputation is needed if these change
+     */
+    private void precomputeFallThroughFlag(final Node node) {
+        CommunicationGroup group = groupMap.get(node);
+        if (node instanceof Receiver) {
+            IGroupable mailbox = ((Receiver) node).getMailbox();
+            if (mailbox instanceof FallThroughCapableMailbox) {
+                Set<Node> directParents = dependencyGraph.getSourceNodes(node).distinctValues();
+                // decide between using quick&cheap fall-through, or allowing for update cancellation
+                boolean fallThrough =
+                        // disallow fallthrough: updates at production nodes should cancel, if they can be trimmed or
+                        // disjunctive
+                        (!(node instanceof ProductionNode && ( // it is a production node...
+                        // with more than one parent
+                        directParents.size() > 0 ||
+                        // or true trimming in its sole parent
+                                directParents.size() == 1 && trueTrimming(directParents.iterator().next())))) &&
+                        // disallow fallthrough: external updates should be stored (if updates are delayed)
+                                (!(node instanceof ExternalInputEnumeratorNode)) &&
+                        // disallow fallthrough: RelationEvaluatorNode needs to be notified in batch-style, and the batching is done by the mailbox
+                        // however, it is not the RelationEvaluatorNode itself that is interesting here, as that indirectly uses the BatchingReceiver
+                        // so we need to disable fall-through for the BatchingReceiver
+                                (!(node instanceof RelationEvaluatorNode.BatchingReceiver));
+                // do additional checks
+                if (fallThrough) {
+                    // recursive parent groups generate excess updates that should be cancelled after delete&rederive
+                    // phases
+                    // aggregator and transitive closure parent nodes also generate excess updates that should be
+                    // cancelled
+                    directParentLoop: for (Node directParent : directParents) {
+                        Set<Node> parentsToCheck = new HashSet<>();
+                        // check the case where a direct parent is the reason for mailbox usage
+                        parentsToCheck.add(directParent);
+                        // check the case where an indirect parent (join slot) is the reason for mailbox usage
+                        if (directParent instanceof DualInputNode) {
+                            // in case of existence join (typically antijoin), a mailbox should allow
+                            // an insertion and deletion (at the secondary slot) to cancel each other out
+                            if (directParent instanceof ExistenceNode) {
+                                fallThrough = false;
+                                break directParentLoop;
+                            }
+                            // in beta nodes, indexer slots (or their active nodes) are considered indirect parents
+                            DualInputNode dualInput = (DualInputNode) directParent;
+                            IterableIndexer primarySlot = dualInput.getPrimarySlot();
+                            if (primarySlot != null)
+                                parentsToCheck.add(primarySlot.getActiveNode());
+                            Indexer secondarySlot = dualInput.getSecondarySlot();
+                            if (secondarySlot != null)
+                                parentsToCheck.add(secondarySlot.getActiveNode());
+                        }
+                        for (Node parent : parentsToCheck) {
+                            CommunicationGroup parentGroup = groupMap.get(parent);
+                            if ( // parent is in a different, recursive group
+                            (group != parentGroup && parentGroup.isRecursive()) ||
+                            // node and parent within the same recursive group, and...
+                                    (group == parentGroup && group.isRecursive() && (
+                                    // parent is a transitive closure or aggregator node, or a trimmer
+                                    // allow trimmed or disjunctive tuple updates to cancel each other
+                                    (parent instanceof TransitiveClosureNode) || (parent instanceof IAggregatorNode)
+                                            || trueTrimming(parent)))) {
+                                fallThrough = false;
+                                break directParentLoop;
+                            }
+                        }
+                    }
+                }
+                // overwrite fallthrough flag with newly computed value
+                ((FallThroughCapableMailbox) mailbox).setFallThrough(fallThrough);
+            }
+        }
+    }
+
+    /**
+     * A trimmer node that actually eliminates some columns (not just reorders)
+     */
+    private boolean trueTrimming(Node node) {
+        if (node instanceof TrimmerNode) {
+            TupleMask mask = ((TrimmerNode) node).getMask();
+            return (mask.indices.length != mask.sourceWidth);
+        }
+        return false;
+    }
+
+    public void activateUnenqueued(final CommunicationGroup group) {
+        groupQueue.add(group);
+        group.isEnqueued = true;
+    }
+
+    public void deactivate(final CommunicationGroup group) {
+        groupQueue.remove(group);
+        group.isEnqueued = false;
+    }
+
+    public CommunicationGroup getAndRemoveFirstGroup() {
+        final CommunicationGroup group = groupQueue.poll();
+        group.isEnqueued = false;
+        return group;
+    }
+
+    public boolean isEmpty() {
+        return groupQueue.isEmpty();
+    }
+
+    protected abstract CommunicationGroup createGroup(final Node representative, final int index);
+
+    protected CommunicationGroup createAndStoreGroup(final Node representative, final int index) {
+        final CommunicationGroup group = createGroup(representative, index);
+        addToGroup(representative, group);
+        return group;
+    }
+
+    /**
+     * Registers the dependency that the target {@link Node} depends on the source {@link Node}. In other words, source
+     * may send messages to target in the RETE network. If the dependency edge is already present, this method call is a
+     * noop.
+     *
+     * @param source
+     *            the source node
+     * @param target
+     *            the target node
+     */
+    public void registerDependency(final Node source, final Node target) {
+        // nodes can be immediately inserted, if they already exist in the graph, this is a noop
+        dependencyGraph.insertNode(source);
+        dependencyGraph.insertNode(target);
+
+        if (!this.dependencyGraph.getTargetNodes(source).containsNonZero(target)) {
+
+            // query all these information before the actual edge insertion
+            // because SCCs may be unified during the process
+            final Node sourceRepresentative = sccInformationProvider.getRepresentative(source);
+            final Node targetRepresentative = sccInformationProvider.getRepresentative(target);
+            final boolean targetHadOutgoingEdges = sccInformationProvider.hasOutgoingEdges(targetRepresentative);
+
+            // insert the edge
+            dependencyGraph.insertEdge(source, target);
+
+            // create groups if they do not yet exist
+            CommunicationGroup sourceGroup = groupMap.get(sourceRepresentative);
+            if (sourceGroup == null) {
+                // create on-demand with the next smaller group id
+                sourceGroup = createAndStoreGroup(sourceRepresentative, --minGroupId);
+            }
+            final int sourceIndex = sourceGroup.identifier;
+
+            CommunicationGroup targetGroup = groupMap.get(targetRepresentative);
+            if (targetGroup == null) {
+                // create on-demand with the next larger group id
+                targetGroup = createAndStoreGroup(targetRepresentative, ++maxGroupId);
+            }
+            final int targetIndex = targetGroup.identifier;
+
+            if (sourceIndex <= targetIndex) {
+                // indices obey current topological ordering
+                refreshFallThroughFlag(target);
+                postProcessNode(source);
+                postProcessNode(target);
+                postProcessGroup(sourceGroup);
+                if (sourceGroup != targetGroup) {
+                    postProcessGroup(targetGroup);
+                }
+            } else if (sourceIndex > targetIndex && !targetHadOutgoingEdges) {
+                // indices violate current topological ordering, but we can simply bump the target index
+                final boolean wasEnqueued = targetGroup.isEnqueued;
+                if (wasEnqueued) {
+                    groupQueue.remove(targetGroup);
+                }
+                targetGroup.identifier = ++maxGroupId;
+                if (wasEnqueued) {
+                    groupQueue.add(targetGroup);
+                }
+
+                refreshFallThroughFlag(target);
+                postProcessNode(source);
+                postProcessNode(target);
+                postProcessGroup(sourceGroup);
+                postProcessGroup(targetGroup);
+            } else {
+                // needs a full re-computation because of more complex change
+                precomputeGroups();
+            }
+        }
+    }
+
+    /**
+     * Returns true if the given {@link Node} is in a recursive {@link CommunicationGroup}, false otherwise.
+     */
+    public boolean isInRecursiveGroup(final Node node) {
+        final CommunicationGroup group = this.getGroup(node);
+        if (group == null) {
+            return false;
+        } else {
+            return group.isRecursive();
+        }
+    }
+
+    /**
+     * Returns true if the given two {@link Node}s are in the same {@link CommunicationGroup}.
+     */
+    public boolean areInSameGroup(final Node left, final Node right) {
+        final CommunicationGroup leftGroup = this.getGroup(left);
+        final CommunicationGroup rightGroup = this.getGroup(right);
+        return leftGroup != null && leftGroup == rightGroup;
+    }
+
+    /**
+     * Unregisters a dependency between source and target.
+     *
+     * @param source
+     *            the source node
+     * @param target
+     *            the target node
+     */
+    public void unregisterDependency(final Node source, final Node target) {
+        // delete the edge first, and then query the SCC info provider
+        this.dependencyGraph.deleteEdgeIfExists(source, target);
+
+        final Node sourceRepresentative = sccInformationProvider.getRepresentative(source);
+        final Node targetRepresentative = sccInformationProvider.getRepresentative(target);
+
+        // if they are still in the same SCC,
+        // then this deletion did not affect the SCCs,
+        // and it is sufficient to recompute affected fall-through flags;
+        // otherwise, we need a new pre-computation for the groupMap and groupQueue
+        if (sourceRepresentative.equals(targetRepresentative)) {
+            // this deletion could not have affected the split flags
+            refreshFallThroughFlag(target);
+            postProcessNode(source);
+            postProcessNode(target);
+        } else {
+            // preComputeGroups takes care of the split flag maintenance
+            precomputeGroups();
+        }
+    }
+
+    /**
+     * Refresh fall-through flags if dependencies change for given target, but no SCC change
+     */
+    private void refreshFallThroughFlag(final Node target) {
+        precomputeFallThroughFlag(target);
+        if (target instanceof DualInputNode) {
+            for (final Node indirectTarget : dependencyGraph.getTargetNodes(target).distinctValues()) {
+                precomputeFallThroughFlag(indirectTarget);
+            }
+        }
+    }
+
+    /**
+     * Returns true if the given source-target edge in the communication network acts as a recursion cut point.
+     * The current implementation considers edges leading into {@link ProductionNode}s as cut point iff
+     * both source and target belong to the same group.
+     *
+     * @param source the source node
+     * @param target the target node
+     * @return true if the edge is a cut point, false otherwise
+     * @since 2.4
+     */
+    protected boolean isRecursionCutPoint(final Node source, final Node target) {
+        final Node effectiveSource = source instanceof SpecializedProjectionIndexer
+                ? ((SpecializedProjectionIndexer) source).getActiveNode()
+                : source;
+        final CommunicationGroup sourceGroup = this.getGroup(effectiveSource);
+        final CommunicationGroup targetGroup = this.getGroup(target);
+        return sourceGroup != null && sourceGroup == targetGroup && target instanceof ProductionNode;
+    }
+
+    /**
+     * This hook allows concrete tracker implementations to perform tracker-specific post processing on nodes (cf.
+     * {@link NetworkStructureChangeSensitiveNode} and {@link BehaviorChangingMailbox}). At the time of the invocation,
+     * the network topology has already been updated.
+     */
+    protected abstract void postProcessNode(final Node node);
+
+    /**
+     * This hook allows concrete tracker implementations to perform tracker-specific post processing on groups. At the
+     * time of the invocation, the network topology has already been updated.
+     * @since 2.4
+     */
+    protected abstract void postProcessGroup(final CommunicationGroup group);
+
+    /**
+     * Creates a proxy for the given {@link Mailbox} for the given requester {@link Node}. The proxy creation is
+     * {@link CommunicationTracker}-specific and depends on the identity of the requester. This method is primarily used
+     * to create {@link TimelyMailboxProxy}s depending on the network topology. There is no guarantee that the same
+     * proxy instance is returned when this method is called multiple times with the same arguments.
+     */
+    public abstract Mailbox proxifyMailbox(final Node requester, final Mailbox original);
+
+    /**
+     * Creates a proxy for the given {@link IndexerListener} for the given requester {@link Node}. The proxy creation is
+     * {@link CommunicationTracker}-specific and depends on the identity of the requester. This method is primarily used
+     * to create {@link TimelyIndexerListenerProxy}s depending on the network topology. There is no guarantee that the
+     * same proxy instance is returned when this method is called multiple times with the same arguments.
+     */
+    public abstract IndexerListener proxifyIndexerListener(final Node requester, final IndexerListener original);
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/MessageSelector.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/MessageSelector.java
new file mode 100644
index 00000000..e1a61693
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/MessageSelector.java
@@ -0,0 +1,19 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2018, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.communication;
+
+/**
+ * Subclasses of this interface represent meta data of update messages in Rete. 
+ * 
+ * @author Tamas Szabo
+ * @since 2.3
+ */
+public interface MessageSelector {
+    
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/NodeComparator.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/NodeComparator.java
new file mode 100644
index 00000000..27779352
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/NodeComparator.java
@@ -0,0 +1,32 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2019, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.communication;
+
+import java.util.Comparator;
+import java.util.Map;
+
+import tools.refinery.viatra.runtime.rete.network.Node;
+
+/**
+ * @since 2.4
+ */
+public class NodeComparator implements Comparator<Node> {
+
+    protected final Map<Node, Integer> nodeMap;
+
+    public NodeComparator(final Map<Node, Integer> nodeMap) {
+        this.nodeMap = nodeMap;
+    }
+
+    @Override
+    public int compare(final Node left, final Node right) {
+        return this.nodeMap.get(left) - this.nodeMap.get(right);
+    }
+    
+}
\ No newline at end of file
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/PhasedSelector.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/PhasedSelector.java
new file mode 100644
index 00000000..41cd8cd3
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/PhasedSelector.java
@@ -0,0 +1,34 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2017, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.communication;
+
+/**
+ * A default message selector that can be used to associate phases to messages. 
+ * 
+ * @author Tamas Szabo
+ * @since 2.3
+ */
+public enum PhasedSelector implements MessageSelector {
+    
+    /**
+     * No special distinguishing feature
+     */
+    DEFAULT,
+    
+    /**
+     * Inserts and delete-insert monotone change pairs
+     */
+    MONOTONE,
+    
+    /**
+     * Deletes
+     */
+    ANTI_MONOTONE
+    
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/Timestamp.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/Timestamp.java
new file mode 100644
index 00000000..a50a63a8
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/Timestamp.java
@@ -0,0 +1,124 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2018, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.communication;
+
+import java.util.AbstractMap;
+import java.util.Collection;
+import java.util.Map;
+import java.util.Set;
+
+import tools.refinery.viatra.runtime.matchers.util.timeline.Timeline;
+import tools.refinery.viatra.runtime.matchers.util.timeline.Timelines;
+
+/**
+ * A timestamp associated with update messages in timely evaluation.
+ * 
+ * @author Tamas Szabo
+ * @since 2.3
+ */
+public class Timestamp implements Comparable<Timestamp>, MessageSelector {
+
+    protected final int value;
+    public static final Timestamp ZERO = new Timestamp(0);
+    /**
+     * @since 2.4
+     */
+    public static final Timeline<Timestamp> INSERT_AT_ZERO_TIMELINE = Timelines.createFrom(Timestamp.ZERO);
+
+    public Timestamp(final int value) {
+        this.value = value;
+    }
+
+    public int getValue() {
+        return value;
+    }
+
+    public Timestamp max(final Timestamp that) {
+        if (this.value >= that.value) {
+            return this;
+        } else {
+            return that;
+        }
+    }
+    
+    /**
+     * @since 2.4
+     */
+    public Timestamp min(final Timestamp that) {
+        if (this.value <= that.value) {
+            return this;
+        } else {
+            return that;
+        }
+    }
+
+    @Override
+    public int compareTo(final Timestamp that) {
+        return this.value - that.value;
+    }
+
+    @Override
+    public boolean equals(final Object obj) {
+        if (obj == null || !(obj instanceof Timestamp)) {
+            return false;
+        } else {
+            return this.value == ((Timestamp) obj).value;
+        }
+    }
+
+    @Override
+    public int hashCode() {
+        return this.value;
+    }
+
+    @Override
+    public String toString() {
+        return Integer.toString(this.value);
+    }
+    
+    /**
+     * A {@link Map} implementation that associates the zero timestamp with every key. There is no suppor for
+     * {@link Map#entrySet()} due to performance reasons.
+     * 
+     * @author Tamas Szabo
+     */
+    public static final class AllZeroMap<T> extends AbstractMap<T, Timeline<Timestamp>> {
+
+        private final Collection<T> wrapped;
+
+        public AllZeroMap(Set<T> wrapped) {
+            this.wrapped = wrapped;
+        }
+
+        @Override
+        public Set<Entry<T, Timeline<Timestamp>>> entrySet() {
+            throw new UnsupportedOperationException("Use the combination of keySet() and get()!");
+        }
+
+        /**
+         * @since 2.4
+         */
+        @Override
+        public Timeline<Timestamp> get(final Object key) {
+            return INSERT_AT_ZERO_TIMELINE;
+        }
+
+        @Override
+        public Set<T> keySet() {
+            return (Set<T>) this.wrapped;
+        }
+
+        @Override
+        public String toString() {
+            return this.getClass().getSimpleName() + ": " + this.keySet().toString();
+        }
+
+    }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timeless/RecursiveCommunicationGroup.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timeless/RecursiveCommunicationGroup.java
new file mode 100644
index 00000000..d8260384
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timeless/RecursiveCommunicationGroup.java
@@ -0,0 +1,164 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2019, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.communication.timeless;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.EnumMap;
+import java.util.LinkedHashSet;
+import java.util.Map;
+import java.util.Set;
+
+import tools.refinery.viatra.runtime.matchers.util.CollectionsFactory;
+import tools.refinery.viatra.runtime.rete.network.Node;
+import tools.refinery.viatra.runtime.rete.network.RederivableNode;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationGroup;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationTracker;
+import tools.refinery.viatra.runtime.rete.network.communication.MessageSelector;
+import tools.refinery.viatra.runtime.rete.network.communication.PhasedSelector;
+import tools.refinery.viatra.runtime.rete.network.mailbox.Mailbox;
+
+/**
+ * A communication group representing either a single node where the
+ * node is a monotonicity aware one or a set of nodes that form an SCC. 
+ * 
+ * @author Tamas Szabo
+ * @since 2.4
+ */
+public class RecursiveCommunicationGroup extends CommunicationGroup {
+
+    private final Set<Mailbox> antiMonotoneMailboxes;
+    private final Set<Mailbox> monotoneMailboxes;
+    private final Set<Mailbox> defaultMailboxes;
+    private final Set<RederivableNode> rederivables;
+    private boolean currentlyDelivering;
+
+    /**
+     * @since 1.7
+     */
+    public RecursiveCommunicationGroup(final CommunicationTracker tracker, final Node representative, final int identifier) {
+        super(tracker, representative, identifier);
+        this.antiMonotoneMailboxes = CollectionsFactory.createSet();
+        this.monotoneMailboxes = CollectionsFactory.createSet();
+        this.defaultMailboxes = CollectionsFactory.createSet();
+        this.rederivables = new LinkedHashSet<RederivableNode>();
+        this.currentlyDelivering = false;
+    }
+
+    @Override
+    public void deliverMessages() {
+        this.currentlyDelivering = true;
+        
+        // ANTI-MONOTONE PHASE
+        while (!this.antiMonotoneMailboxes.isEmpty() || !this.defaultMailboxes.isEmpty()) {
+            while (!this.antiMonotoneMailboxes.isEmpty()) {
+                final Mailbox mailbox = this.antiMonotoneMailboxes.iterator().next();
+                this.antiMonotoneMailboxes.remove(mailbox);
+                mailbox.deliverAll(PhasedSelector.ANTI_MONOTONE);
+            }
+            while (!this.defaultMailboxes.isEmpty()) {
+                final Mailbox mailbox = this.defaultMailboxes.iterator().next();
+                this.defaultMailboxes.remove(mailbox);
+                mailbox.deliverAll(PhasedSelector.DEFAULT);
+            }
+        }
+
+        // REDERIVE PHASE
+        while (!this.rederivables.isEmpty()) {
+            // re-derivable nodes take care of their unregistration!!
+            final RederivableNode node = this.rederivables.iterator().next();
+            node.rederiveOne();
+        }
+
+        // MONOTONE PHASE
+        while (!this.monotoneMailboxes.isEmpty() || !this.defaultMailboxes.isEmpty()) {
+            while (!this.monotoneMailboxes.isEmpty()) {
+                final Mailbox mailbox = this.monotoneMailboxes.iterator().next();
+                this.monotoneMailboxes.remove(mailbox);
+                mailbox.deliverAll(PhasedSelector.MONOTONE);
+            }
+            while (!this.defaultMailboxes.isEmpty()) {
+                final Mailbox mailbox = this.defaultMailboxes.iterator().next();
+                this.defaultMailboxes.remove(mailbox);
+                mailbox.deliverAll(PhasedSelector.DEFAULT);
+            }
+        }
+        
+        this.currentlyDelivering = false;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return this.rederivables.isEmpty() && this.antiMonotoneMailboxes.isEmpty()
+                && this.monotoneMailboxes.isEmpty() && this.defaultMailboxes.isEmpty();
+    }
+
+    @Override
+    public void notifyHasMessage(final Mailbox mailbox, final MessageSelector kind) {
+        final Collection<Mailbox> mailboxes = getMailboxContainer(kind);
+        mailboxes.add(mailbox);
+        if (!this.isEnqueued && !this.currentlyDelivering) {
+            this.tracker.activateUnenqueued(this);
+        }
+    }
+
+    @Override
+    public void notifyLostAllMessages(final Mailbox mailbox, final MessageSelector kind) {
+        final Collection<Mailbox> mailboxes = getMailboxContainer(kind);
+        mailboxes.remove(mailbox);
+        if (isEmpty()) {
+            this.tracker.deactivate(this);
+        }
+    }
+
+    private Collection<Mailbox> getMailboxContainer(final MessageSelector kind) {
+        if (kind == PhasedSelector.ANTI_MONOTONE) {
+            return this.antiMonotoneMailboxes;
+        } else if (kind == PhasedSelector.MONOTONE) {
+            return this.monotoneMailboxes;
+        } else if (kind == PhasedSelector.DEFAULT) {
+            return this.defaultMailboxes;
+        } else {
+            throw new IllegalArgumentException(UNSUPPORTED_MESSAGE_KIND + kind);
+        }
+    }
+
+    public void addRederivable(final RederivableNode node) {
+        this.rederivables.add(node);
+        if (!this.isEnqueued) {
+            this.tracker.activateUnenqueued(this);
+        }
+    }
+
+    public void removeRederivable(final RederivableNode node) {
+        this.rederivables.remove(node);
+        if (isEmpty()) {
+            this.tracker.deactivate(this);
+        }
+    }
+
+    public Collection<RederivableNode> getRederivables() {
+        return this.rederivables;
+    }
+
+    @Override
+    public Map<MessageSelector, Collection<Mailbox>> getMailboxes() {
+        Map<PhasedSelector, Collection<Mailbox>> map = new EnumMap<>(PhasedSelector.class);
+        map.put(PhasedSelector.ANTI_MONOTONE, antiMonotoneMailboxes);
+        map.put(PhasedSelector.MONOTONE, monotoneMailboxes);
+        map.put(PhasedSelector.DEFAULT, defaultMailboxes);
+        return Collections.unmodifiableMap(map);
+    }
+    
+    @Override
+    public boolean isRecursive() {
+        return true;
+    }
+    
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timeless/SingletonCommunicationGroup.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timeless/SingletonCommunicationGroup.java
new file mode 100644
index 00000000..c51c7dbf
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timeless/SingletonCommunicationGroup.java
@@ -0,0 +1,86 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2019, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.communication.timeless;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Map;
+
+import tools.refinery.viatra.runtime.rete.network.Node;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationGroup;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationTracker;
+import tools.refinery.viatra.runtime.rete.network.communication.MessageSelector;
+import tools.refinery.viatra.runtime.rete.network.communication.PhasedSelector;
+import tools.refinery.viatra.runtime.rete.network.mailbox.Mailbox;
+
+/**
+ * A communication group containing only a single node with a single default
+ * mailbox.
+ * 
+ * @author Tamas Szabo
+ * @since 1.6
+ */
+public class SingletonCommunicationGroup extends CommunicationGroup {
+    
+    private Mailbox mailbox;
+
+    /**
+     * @since 1.7
+     */
+    public SingletonCommunicationGroup(final CommunicationTracker tracker, final Node representative, final int identifier) {
+        super(tracker, representative, identifier);
+    }
+
+    @Override
+    public void deliverMessages() {
+        this.mailbox.deliverAll(PhasedSelector.DEFAULT);
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return this.mailbox == null;
+    }
+
+    @Override
+    public void notifyHasMessage(final Mailbox mailbox, final MessageSelector kind) {
+        if (kind == PhasedSelector.DEFAULT) {
+            this.mailbox = mailbox;
+            if (!this.isEnqueued) {
+                this.tracker.activateUnenqueued(this);
+            }
+        } else {
+            throw new IllegalArgumentException(UNSUPPORTED_MESSAGE_KIND + kind);
+        }
+    }
+
+    @Override
+    public void notifyLostAllMessages(final Mailbox mailbox, final MessageSelector kind) {
+        if (kind == PhasedSelector.DEFAULT) {
+            this.mailbox = null;
+            this.tracker.deactivate(this);
+        } else {
+            throw new IllegalArgumentException(UNSUPPORTED_MESSAGE_KIND + kind);
+        }
+    }
+
+    @Override
+    public Map<MessageSelector, Collection<Mailbox>> getMailboxes() {
+        if (mailbox != null) {
+            return Collections.singletonMap(PhasedSelector.DEFAULT, Collections.singleton(mailbox));
+        } else {
+            return Collections.emptyMap();
+        }
+    }
+
+    @Override
+    public boolean isRecursive() {
+        return false;
+    }
+    
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timeless/TimelessCommunicationTracker.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timeless/TimelessCommunicationTracker.java
new file mode 100644
index 00000000..1c18c1cd
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timeless/TimelessCommunicationTracker.java
@@ -0,0 +1,149 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2019, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.communication.timeless;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.Map.Entry;
+
+import tools.refinery.viatra.runtime.rete.index.DualInputNode;
+import tools.refinery.viatra.runtime.rete.index.Indexer;
+import tools.refinery.viatra.runtime.rete.index.IndexerListener;
+import tools.refinery.viatra.runtime.rete.index.IterableIndexer;
+import tools.refinery.viatra.runtime.rete.network.Node;
+import tools.refinery.viatra.runtime.rete.network.Receiver;
+import tools.refinery.viatra.runtime.rete.network.RederivableNode;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationGroup;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationTracker;
+import tools.refinery.viatra.runtime.rete.network.communication.MessageSelector;
+import tools.refinery.viatra.runtime.rete.network.mailbox.Mailbox;
+import tools.refinery.viatra.runtime.rete.network.mailbox.timeless.BehaviorChangingMailbox;
+
+/**
+ * Timeless implementation of the communication tracker.
+ * 
+ * @author Tamas Szabo
+ * @since 2.2
+ */
+public class TimelessCommunicationTracker extends CommunicationTracker {
+
+    @Override
+    protected CommunicationGroup createGroup(Node representative, int index) {
+        final boolean isSingleton = this.sccInformationProvider.sccs.getPartition(representative).size() == 1;
+        final boolean isReceiver = representative instanceof Receiver;
+        final boolean isPosetIndifferent = isReceiver
+                && ((Receiver) representative).getMailbox() instanceof BehaviorChangingMailbox;
+        final boolean isSingletonInDRedMode = isSingleton && (representative instanceof RederivableNode)
+                && ((RederivableNode) representative).isInDRedMode();
+
+        CommunicationGroup group = null;
+        // we can only use a singleton group iff
+        // (1) the SCC has one node AND
+        // (2) either we have a poset-indifferent mailbox OR the node is not even a receiver AND
+        // (3) the node does not run in DRed mode in a singleton group
+        if (isSingleton && (isPosetIndifferent || !isReceiver) && !isSingletonInDRedMode) {
+            group = new SingletonCommunicationGroup(this, representative, index);
+        } else {
+            group = new RecursiveCommunicationGroup(this, representative, index);
+        }
+
+        return group;
+    }
+
+    @Override
+    protected void reconstructQueueContents(final Set<CommunicationGroup> oldActiveGroups) {
+        for (final CommunicationGroup oldGroup : oldActiveGroups) {
+            for (final Entry<MessageSelector, Collection<Mailbox>> entry : oldGroup.getMailboxes().entrySet()) {
+                for (final Mailbox mailbox : entry.getValue()) {
+                    final CommunicationGroup newGroup = this.groupMap.get(mailbox.getReceiver());
+                    newGroup.notifyHasMessage(mailbox, entry.getKey());
+                }
+            }
+
+            if (oldGroup instanceof RecursiveCommunicationGroup) {
+                for (final RederivableNode node : ((RecursiveCommunicationGroup) oldGroup).getRederivables()) {
+                    final CommunicationGroup newGroup = this.groupMap.get(node);
+                    if (!(newGroup instanceof RecursiveCommunicationGroup)) {
+                        throw new IllegalStateException("The new group must also be recursive! " + newGroup);
+                    }
+                    ((RecursiveCommunicationGroup) newGroup).addRederivable(node);
+                }
+            }
+        }
+    }
+
+    @Override
+    public Mailbox proxifyMailbox(final Node requester, final Mailbox original) {
+        return original;
+    }
+
+    @Override
+    public IndexerListener proxifyIndexerListener(final Node requester, final IndexerListener original) {
+        return original;
+    }
+
+    @Override
+    protected void postProcessNode(final Node node) {
+        if (node instanceof Receiver) {
+            final Mailbox mailbox = ((Receiver) node).getMailbox();
+            if (mailbox instanceof BehaviorChangingMailbox) {
+                final CommunicationGroup group = this.groupMap.get(node);
+                final Set<Node> sccNodes = this.sccInformationProvider.sccs.getPartition(node);
+                // a default mailbox must split its messages iff
+                // (1) its receiver is in a recursive group and
+                final boolean c1 = group.isRecursive();
+                // (2) its receiver is at the SCC boundary of that group
+                final boolean c2 = isAtSCCBoundary(node);
+                // (3) its group consists of more than one node
+                final boolean c3 = sccNodes.size() > 1;
+                ((BehaviorChangingMailbox) mailbox).setSplitFlag(c1 && c2 && c3);
+            }
+        }
+    }
+    
+    @Override
+    protected void postProcessGroup(final CommunicationGroup group) {
+        
+    }
+
+    /**
+     * @since 2.0
+     */
+    private boolean isAtSCCBoundary(final Node node) {
+        final CommunicationGroup ownGroup = this.groupMap.get(node);
+        assert ownGroup != null;
+        for (final Node source : this.dependencyGraph.getSourceNodes(node).distinctValues()) {
+            final Set<Node> sourcesToCheck = new HashSet<Node>();
+            sourcesToCheck.add(source);
+            // DualInputNodes must be checked additionally because they do not use a mailbox directly.
+            // It can happen that their indexers actually belong to other SCCs.
+            if (source instanceof DualInputNode) {
+                final DualInputNode dualInput = (DualInputNode) source;
+                final IterableIndexer primarySlot = dualInput.getPrimarySlot();
+                if (primarySlot != null) {
+                    sourcesToCheck.add(primarySlot.getActiveNode());
+                }
+                final Indexer secondarySlot = dualInput.getSecondarySlot();
+                if (secondarySlot != null) {
+                    sourcesToCheck.add(secondarySlot.getActiveNode());
+                }
+            }
+            for (final Node current : sourcesToCheck) {
+                final CommunicationGroup otherGroup = this.groupMap.get(current);
+                assert otherGroup != null;
+                if (!ownGroup.equals(otherGroup)) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/ResumableNode.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/ResumableNode.java
new file mode 100644
index 00000000..8097bd91
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/ResumableNode.java
@@ -0,0 +1,36 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2016, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.communication.timely;
+
+import tools.refinery.viatra.runtime.rete.network.IGroupable;
+import tools.refinery.viatra.runtime.rete.network.Node;
+import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
+
+/**
+ * {@link Node}s that implement this interface can resume folding of their states when instructed during timely evaluation. 
+ * 
+ * @since 2.3
+ * @author Tamas Szabo
+ */
+public interface ResumableNode extends Node, IGroupable {
+    
+    /**
+     * When called, the folding of the state shall be resumed at the given timestamp. The resumable is expected to
+     * do a folding step at the given timestamp only. Afterwards, folding shall be interrupted, even if there is more
+     * folding to do towards higher timestamps.
+     */
+    public void resumeAt(final Timestamp timestamp);
+
+    /**
+     * Returns the smallest timestamp where lazy folding shall be resumed, or null if there is no more folding to do in this
+     * resumable.
+     */
+    public Timestamp getResumableTimestamp();
+    
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/TimelyCommunicationGroup.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/TimelyCommunicationGroup.java
new file mode 100644
index 00000000..0394d92c
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/TimelyCommunicationGroup.java
@@ -0,0 +1,171 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2019, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.communication.timely;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.TreeSet;
+
+import org.apache.log4j.Logger;
+import tools.refinery.viatra.runtime.matchers.util.CollectionsFactory;
+import tools.refinery.viatra.runtime.rete.network.Node;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationGroup;
+import tools.refinery.viatra.runtime.rete.network.communication.MessageSelector;
+import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
+import tools.refinery.viatra.runtime.rete.network.mailbox.Mailbox;
+import tools.refinery.viatra.runtime.rete.network.mailbox.timely.TimelyMailbox;
+import tools.refinery.viatra.runtime.rete.util.Options;
+
+/**
+ * A timely communication group implementation. {@link TimelyMailbox}es and {@link LazyFoldingNode}s are ordered in the
+ * increasing order of timestamps.
+ * 
+ * @author Tamas Szabo
+ * @since 2.3
+ */
+public class TimelyCommunicationGroup extends CommunicationGroup {
+
+    private final boolean isSingleton;
+    private final TreeMap<Timestamp, Set<Mailbox>> mailboxQueue;
+    // may be null - only used in the scattered case where we need to take care of mailboxes and resumables too
+    private Comparator<Node> nodeComparator;
+    private boolean currentlyDelivering;
+    private Timestamp currentlyDeliveredTimestamp;
+
+    public TimelyCommunicationGroup(final TimelyCommunicationTracker tracker, final Node representative,
+            final int identifier, final boolean isSingleton) {
+        super(tracker, representative, identifier);
+        this.isSingleton = isSingleton;
+        this.mailboxQueue = CollectionsFactory.createTreeMap();
+        this.currentlyDelivering = false;
+    }
+
+    /**
+     * Sets the {@link Comparator} to be used to order the {@link Mailbox}es at a given {@link Timestamp} in the mailbox
+     * queue. Additionally, reorders already queued {@link Mailbox}es to reflect the new comparator. The comparator may
+     * be null, in this case, no set ordering will be enforced among the {@link Mailbox}es.
+     */
+    public void setComparatorAndReorderMailboxes(final Comparator<Node> nodeComparator) {
+        this.nodeComparator = nodeComparator;
+        if (!this.mailboxQueue.isEmpty()) {
+            final HashMap<Timestamp, Set<Mailbox>> queueCopy = new HashMap<Timestamp, Set<Mailbox>>(this.mailboxQueue);
+            this.mailboxQueue.clear();
+            for (final Entry<Timestamp, Set<Mailbox>> entry : queueCopy.entrySet()) {
+                for (final Mailbox mailbox : entry.getValue()) {
+                    this.notifyHasMessage(mailbox, entry.getKey());
+                }
+            }
+        }
+    }
+
+    @Override
+    public void deliverMessages() {
+        this.currentlyDelivering = true;
+        while (!this.mailboxQueue.isEmpty()) {
+            // care must be taken here how we iterate over the mailboxes
+            // it is not okay to loop over the mailboxes at once because a mailbox may disappear from the collection as
+            // a result of delivering messages from another mailboxes under the same timestamp
+            // because of this, it is crucial that we pick the mailboxes one by one
+            final Entry<Timestamp, Set<Mailbox>> entry = this.mailboxQueue.firstEntry();
+            final Timestamp timestamp = entry.getKey();
+            final Set<Mailbox> mailboxes = entry.getValue();
+            final Mailbox mailbox = mailboxes.iterator().next();
+            mailboxes.remove(mailbox);
+            if (mailboxes.isEmpty()) {
+                this.mailboxQueue.pollFirstEntry();
+            }
+            assert mailbox instanceof TimelyMailbox;
+            /* debug */ this.currentlyDeliveredTimestamp = timestamp;
+            mailbox.deliverAll(timestamp);
+            /* debug */ this.currentlyDeliveredTimestamp = null;
+        }
+        this.currentlyDelivering = false;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return this.mailboxQueue.isEmpty();
+    }
+
+    @Override
+    public void notifyHasMessage(final Mailbox mailbox, MessageSelector kind) {
+        if (kind instanceof Timestamp) {
+            final Timestamp timestamp = (Timestamp) kind;
+            if (Options.MONITOR_VIOLATION_OF_DIFFERENTIAL_DATAFLOW_TIMESTAMPS) {
+                if (timestamp.compareTo(this.currentlyDeliveredTimestamp) < 0) {
+                    final Logger logger = this.representative.getContainer().getNetwork().getEngine().getLogger();
+                    logger.error(
+                            "[INTERNAL ERROR] Violation of differential dataflow communication schema! The communication component with representative "
+                                    + this.representative + " observed decreasing timestamp during message delivery!");
+                }
+            }
+            final Set<Mailbox> mailboxes = this.mailboxQueue.computeIfAbsent(timestamp, k -> {
+                if (this.nodeComparator == null) {
+                    return CollectionsFactory.createSet();
+                } else {
+                    return new TreeSet<Mailbox>(new Comparator<Mailbox>() {
+                        @Override
+                        public int compare(final Mailbox left, final Mailbox right) {
+                            return nodeComparator.compare(left.getReceiver(), right.getReceiver());
+                        }
+                    });
+                }
+            });
+            mailboxes.add(mailbox);
+            if (!this.isEnqueued && !this.currentlyDelivering) {
+                this.tracker.activateUnenqueued(this);
+            }
+        } else {
+            throw new IllegalArgumentException(UNSUPPORTED_MESSAGE_KIND + kind);
+        }
+    }
+
+    @Override
+    public void notifyLostAllMessages(final Mailbox mailbox, final MessageSelector kind) {
+        if (kind instanceof Timestamp) {
+            final Timestamp timestamp = (Timestamp) kind;
+            this.mailboxQueue.compute(timestamp, (k, v) -> {
+                if (v == null) {
+                    throw new IllegalStateException("No mailboxes registered at timestamp " + timestamp + "!");
+                }
+                if (!v.remove(mailbox)) {
+                    throw new IllegalStateException(
+                            "The mailbox " + mailbox + " was not registered at timestamp " + timestamp + "!");
+                }
+                if (v.isEmpty()) {
+                    return null;
+                } else {
+                    return v;
+                }
+            });
+            if (this.mailboxQueue.isEmpty()) {
+                this.tracker.deactivate(this);
+            }
+        } else {
+            throw new IllegalArgumentException(UNSUPPORTED_MESSAGE_KIND + kind);
+        }
+    }
+
+    @Override
+    public Map<MessageSelector, Collection<Mailbox>> getMailboxes() {
+        return Collections.unmodifiableMap(this.mailboxQueue);
+    }
+
+    @Override
+    public boolean isRecursive() {
+        return !this.isSingleton;
+    }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/TimelyCommunicationTracker.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/TimelyCommunicationTracker.java
new file mode 100644
index 00000000..79179880
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/TimelyCommunicationTracker.java
@@ -0,0 +1,216 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2019, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.communication.timely;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+import java.util.function.Function;
+
+import tools.refinery.viatra.runtime.rete.itc.alg.misc.topsort.TopologicalSorting;
+import tools.refinery.viatra.runtime.rete.itc.graphimpl.Graph;
+import tools.refinery.viatra.runtime.matchers.util.CollectionsFactory;
+import tools.refinery.viatra.runtime.rete.index.IndexerListener;
+import tools.refinery.viatra.runtime.rete.index.SpecializedProjectionIndexer;
+import tools.refinery.viatra.runtime.rete.index.SpecializedProjectionIndexer.ListenerSubscription;
+import tools.refinery.viatra.runtime.rete.index.StandardIndexer;
+import tools.refinery.viatra.runtime.rete.matcher.TimelyConfiguration;
+import tools.refinery.viatra.runtime.rete.matcher.TimelyConfiguration.TimelineRepresentation;
+import tools.refinery.viatra.runtime.rete.network.NetworkStructureChangeSensitiveNode;
+import tools.refinery.viatra.runtime.rete.network.Node;
+import tools.refinery.viatra.runtime.rete.network.ProductionNode;
+import tools.refinery.viatra.runtime.rete.network.StandardNode;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationGroup;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationTracker;
+import tools.refinery.viatra.runtime.rete.network.communication.MessageSelector;
+import tools.refinery.viatra.runtime.rete.network.communication.NodeComparator;
+import tools.refinery.viatra.runtime.rete.network.mailbox.Mailbox;
+import tools.refinery.viatra.runtime.rete.single.DiscriminatorDispatcherNode;
+
+/**
+ * Timely (DDF) implementation of the {@link CommunicationTracker}.
+ *
+ * @author Tamas Szabo
+ * @since 2.3
+ */
+public class TimelyCommunicationTracker extends CommunicationTracker {
+
+    protected final TimelyConfiguration configuration;
+
+    public TimelyCommunicationTracker(final TimelyConfiguration configuration) {
+        this.configuration = configuration;
+    }
+
+    @Override
+    protected CommunicationGroup createGroup(final Node representative, final int index) {
+        final boolean isSingleton = this.sccInformationProvider.sccs.getPartition(representative).size() == 1;
+        return new TimelyCommunicationGroup(this, representative, index, isSingleton);
+    }
+
+    @Override
+    protected void reconstructQueueContents(final Set<CommunicationGroup> oldActiveGroups) {
+        for (final CommunicationGroup oldGroup : oldActiveGroups) {
+            for (final Entry<MessageSelector, Collection<Mailbox>> entry : oldGroup.getMailboxes().entrySet()) {
+                for (final Mailbox mailbox : entry.getValue()) {
+                    final CommunicationGroup newGroup = this.groupMap.get(mailbox.getReceiver());
+                    newGroup.notifyHasMessage(mailbox, entry.getKey());
+                }
+            }
+        }
+    }
+
+    @Override
+    public Mailbox proxifyMailbox(final Node requester, final Mailbox original) {
+        final Mailbox mailboxToProxify = (original instanceof TimelyMailboxProxy)
+                ? ((TimelyMailboxProxy) original).getWrappedMailbox()
+                : original;
+        final TimestampTransformation preprocessor = getPreprocessor(requester, mailboxToProxify.getReceiver());
+        if (preprocessor == null) {
+            return mailboxToProxify;
+        } else {
+            return new TimelyMailboxProxy(mailboxToProxify, preprocessor);
+        }
+    }
+
+    @Override
+    public IndexerListener proxifyIndexerListener(final Node requester, final IndexerListener original) {
+        final IndexerListener listenerToProxify = (original instanceof TimelyIndexerListenerProxy)
+                ? ((TimelyIndexerListenerProxy) original).getWrappedIndexerListener()
+                : original;
+        final TimestampTransformation preprocessor = getPreprocessor(requester, listenerToProxify.getOwner());
+        if (preprocessor == null) {
+            return listenerToProxify;
+        } else {
+            return new TimelyIndexerListenerProxy(listenerToProxify, preprocessor);
+        }
+    }
+
+    protected TimestampTransformation getPreprocessor(final Node source, final Node target) {
+        final Node effectiveSource = source instanceof SpecializedProjectionIndexer
+                ? ((SpecializedProjectionIndexer) source).getActiveNode()
+                : source;
+        final CommunicationGroup sourceGroup = this.getGroup(effectiveSource);
+        final CommunicationGroup targetGroup = this.getGroup(target);
+
+        if (sourceGroup != null && targetGroup != null) {
+            // during RETE construction, the groups may be still null
+            if (sourceGroup != targetGroup && sourceGroup.isRecursive()) {
+                // targetGroup is a successor SCC of sourceGroup
+                // and sourceGroup is a recursive SCC
+                // then we need to zero out the timestamps
+                return TimestampTransformation.RESET;
+            }
+            if (sourceGroup == targetGroup && target instanceof ProductionNode) {
+                // if requester and receiver are in the same SCC
+                // and receiver is a production node
+                // then we need to increment the timestamps
+                return TimestampTransformation.INCREMENT;
+            }
+        }
+
+        return null;
+    }
+
+    @Override
+    protected void postProcessNode(final Node node) {
+        if (node instanceof NetworkStructureChangeSensitiveNode) {
+            ((NetworkStructureChangeSensitiveNode) node).networkStructureChanged();
+        }
+    }
+
+    @Override
+    protected void postProcessGroup(final CommunicationGroup group) {
+        if (this.configuration.getTimelineRepresentation() == TimelineRepresentation.FAITHFUL) {
+            final Node representative = group.getRepresentative();
+            final Set<Node> groupMembers = this.sccInformationProvider.sccs.getPartition(representative);
+            if (groupMembers.size() > 1) {
+                final Graph<Node> graph = new Graph<Node>();
+
+                for (final Node node : groupMembers) {
+                    graph.insertNode(node);
+                }
+
+                for (final Node source : groupMembers) {
+                    for (final Node target : this.dependencyGraph.getTargetNodes(source)) {
+                        // (1) the edge is not a recursion cut point
+                        // (2) the edge is within this group
+                        if (!this.isRecursionCutPoint(source, target) && groupMembers.contains(target)) {
+                            graph.insertEdge(source, target);
+                        }
+                    }
+                }
+
+                final List<Node> orderedNodes = TopologicalSorting.compute(graph);
+                final Map<Node, Integer> nodeMap = CollectionsFactory.createMap();
+                int identifier = 0;
+                for (final Node orderedNode : orderedNodes) {
+                    nodeMap.put(orderedNode, identifier++);
+                }
+
+                ((TimelyCommunicationGroup) group).setComparatorAndReorderMailboxes(new NodeComparator(nodeMap));
+            }
+        }
+    }
+
+    /**
+     * This static field is used for debug purposes in the DotGenerator.
+     */
+    public static final Function<Node, Function<Node, String>> EDGE_LABEL_FUNCTION = new Function<Node, Function<Node, String>>() {
+
+        @Override
+        public Function<Node, String> apply(final Node source) {
+            return new Function<Node, String>() {
+                @Override
+                public String apply(final Node target) {
+                    if (source instanceof SpecializedProjectionIndexer) {
+                        final Collection<ListenerSubscription> subscriptions = ((SpecializedProjectionIndexer) source)
+                                .getSubscriptions();
+                        for (final ListenerSubscription subscription : subscriptions) {
+                            if (subscription.getListener().getOwner() == target
+                                    && subscription.getListener() instanceof TimelyIndexerListenerProxy) {
+                                return ((TimelyIndexerListenerProxy) subscription.getListener()).preprocessor
+                                        .toString();
+                            }
+                        }
+                    }
+                    if (source instanceof StandardIndexer) {
+                        final Collection<IndexerListener> listeners = ((StandardIndexer) source).getListeners();
+                        for (final IndexerListener listener : listeners) {
+                            if (listener.getOwner() == target && listener instanceof TimelyIndexerListenerProxy) {
+                                return ((TimelyIndexerListenerProxy) listener).preprocessor.toString();
+                            }
+                        }
+                    }
+                    if (source instanceof StandardNode) {
+                        final Collection<Mailbox> mailboxes = ((StandardNode) source).getChildMailboxes();
+                        for (final Mailbox mailbox : mailboxes) {
+                            if (mailbox.getReceiver() == target && mailbox instanceof TimelyMailboxProxy) {
+                                return ((TimelyMailboxProxy) mailbox).preprocessor.toString();
+                            }
+                        }
+                    }
+                    if (source instanceof DiscriminatorDispatcherNode) {
+                        final Collection<Mailbox> mailboxes = ((DiscriminatorDispatcherNode) source)
+                                .getBucketMailboxes().values();
+                        for (final Mailbox mailbox : mailboxes) {
+                            if (mailbox.getReceiver() == target && mailbox instanceof TimelyMailboxProxy) {
+                                return ((TimelyMailboxProxy) mailbox).preprocessor.toString();
+                            }
+                        }
+                    }
+                    return null;
+                }
+            };
+        }
+
+    };
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/TimelyIndexerListenerProxy.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/TimelyIndexerListenerProxy.java
new file mode 100644
index 00000000..e8fbf84e
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/TimelyIndexerListenerProxy.java
@@ -0,0 +1,81 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2019, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.communication.timely;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+import tools.refinery.viatra.runtime.matchers.util.Preconditions;
+import tools.refinery.viatra.runtime.rete.index.IndexerListener;
+import tools.refinery.viatra.runtime.rete.network.Node;
+import tools.refinery.viatra.runtime.rete.network.ProductionNode;
+import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
+
+/**
+ * A timely proxy for another {@link IndexerListener}, which performs some preprocessing 
+ * on the differential timestamps before passing it on to the real recipient. 
+ * <p>
+ * These proxies are used on edges leading into {@link ProductionNode}s. Because {@link ProductionNode}s 
+ * never ask back the indexer for its contents, there is no need to also apply the proxy on that direction. 
+ * 
+ * @author Tamas Szabo
+ * @since 2.3
+ */
+public class TimelyIndexerListenerProxy implements IndexerListener {
+
+    protected final TimestampTransformation preprocessor;
+    protected final IndexerListener wrapped;
+
+    public TimelyIndexerListenerProxy(final IndexerListener wrapped,
+            final TimestampTransformation preprocessor) {
+        Preconditions.checkArgument(!(wrapped instanceof TimelyIndexerListenerProxy), "Proxy in a proxy is not allowed!");
+        this.wrapped = wrapped;
+        this.preprocessor = preprocessor;
+    }
+    
+    public IndexerListener getWrappedIndexerListener() {
+        return wrapped;
+    }
+
+    @Override
+    public Node getOwner() {
+        return this.wrapped.getOwner();
+    }
+
+    @Override
+    public void notifyIndexerUpdate(final Direction direction, final Tuple updateElement, final Tuple signature,
+            final boolean change, final Timestamp timestamp) {
+        this.wrapped.notifyIndexerUpdate(direction, updateElement, signature, change, preprocessor.process(timestamp));
+    }
+
+    @Override
+    public String toString() {
+        return this.preprocessor.toString() + "_PROXY -> " + this.wrapped.toString();
+    }
+
+    @Override
+    public boolean equals(final Object obj) {
+        if (obj == null || obj.getClass() != this.getClass()) {
+            return false;
+        } else if (obj == this) {
+            return true;
+        } else {
+            final TimelyIndexerListenerProxy that = (TimelyIndexerListenerProxy) obj;
+            return this.wrapped.equals(that.wrapped) && this.preprocessor == that.preprocessor;
+        }
+    }
+
+    @Override
+    public int hashCode() {
+        int hash = 1;
+        hash = hash * 17 + this.wrapped.hashCode();
+        hash = hash * 31 + this.preprocessor.hashCode();
+        return hash;
+    }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/TimelyMailboxProxy.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/TimelyMailboxProxy.java
new file mode 100644
index 00000000..550bfbeb
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/TimelyMailboxProxy.java
@@ -0,0 +1,102 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2019, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.communication.timely;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+import tools.refinery.viatra.runtime.matchers.util.Preconditions;
+import tools.refinery.viatra.runtime.rete.network.Receiver;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationGroup;
+import tools.refinery.viatra.runtime.rete.network.communication.MessageSelector;
+import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
+import tools.refinery.viatra.runtime.rete.network.mailbox.Mailbox;
+
+/**
+ * A timely proxy for another {@link Mailbox}, which performs some preprocessing 
+ * on the differential timestamps before passing it on to the real recipient. 
+ * 
+ * @author Tamas Szabo
+ * @since 2.3
+ */
+public class TimelyMailboxProxy implements Mailbox {
+
+    protected final TimestampTransformation preprocessor;
+    protected final Mailbox wrapped;
+
+    public TimelyMailboxProxy(final Mailbox wrapped, final TimestampTransformation preprocessor) {
+        Preconditions.checkArgument(!(wrapped instanceof TimelyMailboxProxy), "Proxy in a proxy is not allowed!");
+        this.wrapped = wrapped;
+        this.preprocessor = preprocessor;
+    }
+    
+    public Mailbox getWrappedMailbox() {
+        return wrapped;
+    }
+
+    @Override
+    public void postMessage(final Direction direction, final Tuple update, final Timestamp timestamp) {
+        this.wrapped.postMessage(direction, update, preprocessor.process(timestamp));
+    }
+
+    @Override
+    public String toString() {
+        return this.preprocessor.toString() + "_PROXY -> " + this.wrapped.toString();
+    }
+
+    @Override
+    public void clear() {
+        this.wrapped.clear();
+    }
+
+    @Override
+    public void deliverAll(final MessageSelector selector) {
+        this.wrapped.deliverAll(selector);
+    }
+
+    @Override
+    public CommunicationGroup getCurrentGroup() {
+        return this.wrapped.getCurrentGroup();
+    }
+
+    @Override
+    public void setCurrentGroup(final CommunicationGroup group) {
+        this.wrapped.setCurrentGroup(group);
+    }
+
+    @Override
+    public Receiver getReceiver() {
+        return this.wrapped.getReceiver();
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return this.wrapped.isEmpty();
+    }
+
+    @Override
+    public boolean equals(final Object obj) {
+        if (obj == null || obj.getClass() != this.getClass()) {
+            return false;
+        } else if (obj == this) {
+            return true;
+        } else {
+            final TimelyMailboxProxy that = (TimelyMailboxProxy) obj;
+            return this.wrapped.equals(that.wrapped) && this.preprocessor == that.preprocessor;
+        }
+    }
+
+    @Override
+    public int hashCode() {
+        int hash = 1;
+        hash = hash * 17 + this.wrapped.hashCode();
+        hash = hash * 31 + this.preprocessor.hashCode();
+        return hash;
+    }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/TimestampTransformation.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/TimestampTransformation.java
new file mode 100644
index 00000000..8929eb5c
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/communication/timely/TimestampTransformation.java
@@ -0,0 +1,48 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2019, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.communication.timely;
+
+import tools.refinery.viatra.runtime.rete.network.Node;
+import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
+
+/**
+ * Values of this enum perform different kind of preprocessing on {@link Timestamp}s. 
+ * This is used on edges leading in and out from {@link Node}s in recursive {@link TimelyCommunicationGroup}s. 
+ * 
+ * @author Tamas Szabo
+ * @since 2.3
+ */
+public enum TimestampTransformation {
+
+    INCREMENT {
+        @Override
+        public Timestamp process(final Timestamp timestamp) {
+            return new Timestamp(timestamp.getValue() + 1);
+        }
+        
+        @Override
+        public String toString() {
+            return "INCREMENT";
+        }
+    },
+    RESET {
+        @Override
+        public Timestamp process(final Timestamp timestamp) {
+            return Timestamp.ZERO;
+        }
+        
+        @Override
+        public String toString() {
+            return "RESET";
+        }
+    };
+
+    public abstract Timestamp process(final Timestamp timestamp);
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/delayed/DelayedCommand.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/delayed/DelayedCommand.java
new file mode 100644
index 00000000..d6312671
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/delayed/DelayedCommand.java
@@ -0,0 +1,81 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2019, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.delayed;
+
+import java.util.Collection;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+import tools.refinery.viatra.runtime.matchers.util.Signed;
+import tools.refinery.viatra.runtime.matchers.util.timeline.Timeline;
+import tools.refinery.viatra.runtime.rete.network.Network;
+import tools.refinery.viatra.runtime.rete.network.Node;
+import tools.refinery.viatra.runtime.rete.network.Receiver;
+import tools.refinery.viatra.runtime.rete.network.ReteContainer;
+import tools.refinery.viatra.runtime.rete.network.Supplier;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationTracker;
+import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
+import tools.refinery.viatra.runtime.rete.network.mailbox.Mailbox;
+
+/**
+ * Instances of this class are responsible for initializing a {@link Receiver} with the contents of a {@link Supplier}.
+ * However, due to the dynamic nature of the Rete {@link Network} and to the fact that certain {@link Node}s in the
+ * {@link Network} are sensitive to the shape of the {@link Network}, the commands must be delayed until the
+ * construction of the {@link Network} has stabilized.
+ * 
+ * @author Tamas Szabo
+ * @since 2.3
+ */
+public abstract class DelayedCommand implements Runnable {
+
+    protected final Supplier supplier;
+    protected final Receiver receiver;
+    protected final Direction direction;
+    protected final ReteContainer container;
+
+    public DelayedCommand(final Supplier supplier, final Receiver receiver, final Direction direction,
+            final ReteContainer container) {
+        this.supplier = supplier;
+        this.receiver = receiver;
+        this.direction = direction;
+        this.container = container;
+    }
+
+    @Override
+    public void run() {
+        final CommunicationTracker tracker = this.container.getCommunicationTracker();
+        final Mailbox mailbox = tracker.proxifyMailbox(this.supplier, this.receiver.getMailbox());
+
+        if (this.isTimestampAware()) {
+            final Map<Tuple, Timeline<Timestamp>> contents = this.container.pullContentsWithTimeline(this.supplier,
+                    false);
+            for (final Entry<Tuple, Timeline<Timestamp>> entry : contents.entrySet()) {
+                for (final Signed<Timestamp> change : entry.getValue().asChangeSequence()) {
+                    mailbox.postMessage(change.getDirection().multiply(this.direction), entry.getKey(),
+                            change.getPayload());
+                }
+            }
+        } else {
+            final Collection<Tuple> contents = this.container.pullContents(this.supplier, false);
+            for (final Tuple tuple : contents) {
+                mailbox.postMessage(this.direction, tuple, Timestamp.ZERO);
+            }
+        }
+    }
+
+    @Override
+    public String toString() {
+        return this.supplier + " -> " + this.receiver.toString();
+    }
+
+    protected abstract boolean isTimestampAware();
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/delayed/DelayedConnectCommand.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/delayed/DelayedConnectCommand.java
new file mode 100644
index 00000000..1bfdbec6
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/delayed/DelayedConnectCommand.java
@@ -0,0 +1,27 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2019, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.delayed;
+
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+import tools.refinery.viatra.runtime.rete.network.Receiver;
+import tools.refinery.viatra.runtime.rete.network.ReteContainer;
+import tools.refinery.viatra.runtime.rete.network.Supplier;
+
+public class DelayedConnectCommand extends DelayedCommand {
+
+    public DelayedConnectCommand(final Supplier supplier, final Receiver receiver, final ReteContainer container) {
+        super(supplier, receiver, Direction.INSERT, container);
+    }
+
+    @Override
+    protected boolean isTimestampAware() {
+        return this.container.isTimelyEvaluation() && this.container.getCommunicationTracker().areInSameGroup(this.supplier, this.receiver);
+    }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/delayed/DelayedDisconnectCommand.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/delayed/DelayedDisconnectCommand.java
new file mode 100644
index 00000000..5825a971
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/delayed/DelayedDisconnectCommand.java
@@ -0,0 +1,30 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2019, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.delayed;
+
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+import tools.refinery.viatra.runtime.rete.network.Receiver;
+import tools.refinery.viatra.runtime.rete.network.ReteContainer;
+import tools.refinery.viatra.runtime.rete.network.Supplier;
+
+public class DelayedDisconnectCommand extends DelayedCommand {
+
+    protected final boolean wasInSameSCC;
+    
+    public DelayedDisconnectCommand(final Supplier supplier, final Receiver receiver, final ReteContainer container, final boolean wasInSameSCC) {
+        super(supplier, receiver, Direction.DELETE, container);
+        this.wasInSameSCC = wasInSameSCC;
+    }
+    
+    @Override
+    protected boolean isTimestampAware() {
+        return this.wasInSameSCC;
+    }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/indexer/DefaultMessageIndexer.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/indexer/DefaultMessageIndexer.java
new file mode 100644
index 00000000..da9bc47e
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/indexer/DefaultMessageIndexer.java
@@ -0,0 +1,74 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2018, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.indexer;
+
+import java.util.Collections;
+import java.util.Map;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.util.CollectionsFactory;
+
+/**
+ * @author Tamas Szabo
+ * @since 2.0
+ */
+public class DefaultMessageIndexer implements MessageIndexer {
+
+        protected final Map<Tuple, Integer> indexer;
+
+        public DefaultMessageIndexer() {
+                this.indexer = CollectionsFactory.createMap();
+        }
+
+        public Map<Tuple, Integer> getTuples() {
+                return Collections.unmodifiableMap(this.indexer);
+        }
+
+        @Override
+        public int getCount(final Tuple update) {
+                final Integer count = getTuples().get(update);
+                if (count == null) {
+                        return 0;
+                } else {
+                        return count;
+                }
+        }
+
+        @Override
+        public void insert(final Tuple update) {
+                update(update, 1);
+        }
+
+        @Override
+        public void delete(final Tuple update) {
+                update(update, -1);
+        }
+
+        @Override
+        public void update(final Tuple update, final int delta) {
+                final Integer oldCount = this.indexer.get(update);
+                final int newCount = (oldCount == null ? 0 : oldCount) + delta;
+                if (newCount == 0) {
+                        this.indexer.remove(update);
+                } else {
+                        this.indexer.put(update, newCount);
+                }
+        }
+
+        @Override
+        public boolean isEmpty() {
+                return this.indexer.isEmpty();
+        }
+
+        @Override
+        public void clear() {
+                this.indexer.clear();
+        }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/indexer/GroupBasedMessageIndexer.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/indexer/GroupBasedMessageIndexer.java
new file mode 100644
index 00000000..80271252
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/indexer/GroupBasedMessageIndexer.java
@@ -0,0 +1,95 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2018, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.indexer;
+
+import java.util.Collections;
+import java.util.Map;
+import java.util.Set;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.tuple.TupleMask;
+import tools.refinery.viatra.runtime.matchers.util.CollectionsFactory;
+
+/**
+ * @author Tamas Szabo
+ * @since 2.0
+ */
+public class GroupBasedMessageIndexer implements MessageIndexer {
+
+        protected final Map<Tuple, DefaultMessageIndexer> indexer;
+        protected final TupleMask groupMask;
+
+        public GroupBasedMessageIndexer(final TupleMask groupMask) {
+                this.indexer = CollectionsFactory.createMap();
+                this.groupMask = groupMask;
+        }
+
+        public Map<Tuple, Integer> getTuplesByGroup(final Tuple group) {
+                final DefaultMessageIndexer values = this.indexer.get(group);
+                if (values == null) {
+                        return Collections.emptyMap();
+                } else {
+                        return Collections.unmodifiableMap(values.getTuples());
+                }
+        }
+
+        @Override
+        public int getCount(final Tuple update) {
+                final Tuple group = this.groupMask.transform(update);
+                final Integer count = getTuplesByGroup(group).get(update);
+                if (count == null) {
+                        return 0;
+                } else {
+                        return count;
+                }
+        }
+
+        public Set<Tuple> getGroups() {
+                return Collections.unmodifiableSet(this.indexer.keySet());
+        }
+
+        @Override
+        public void insert(final Tuple update) {
+                update(update, 1);
+        }
+
+        @Override
+        public void delete(final Tuple update) {
+                update(update, -1);
+        }
+
+        @Override
+        public void update(final Tuple update, final int delta) {
+                final Tuple group = this.groupMask.transform(update);
+                DefaultMessageIndexer valueIndexer = this.indexer.get(group);
+
+                if (valueIndexer == null) {
+                        valueIndexer = new DefaultMessageIndexer();
+                        this.indexer.put(group, valueIndexer);
+                }
+
+                valueIndexer.update(update, delta);
+
+                // it may happen that the indexer becomes empty as a result of the update
+                if (valueIndexer.isEmpty()) {
+                        this.indexer.remove(group);
+                }
+        }
+
+        @Override
+        public boolean isEmpty() {
+                return this.indexer.isEmpty();
+        }
+
+        @Override
+        public void clear() {
+                this.indexer.clear();
+        }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/indexer/MessageIndexer.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/indexer/MessageIndexer.java
new file mode 100644
index 00000000..271aaa44
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/indexer/MessageIndexer.java
@@ -0,0 +1,33 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2018, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.indexer;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.util.Clearable;
+import tools.refinery.viatra.runtime.rete.network.mailbox.Mailbox;
+
+/**
+ * A message indexer is used by {@link Mailbox}es to index their contents. 
+ * 
+ * @author Tamas Szabo
+ * @since 2.0
+ */
+public interface MessageIndexer extends Clearable {
+        
+        public void insert(final Tuple update);
+
+        public void delete(final Tuple update);
+
+        public void update(final Tuple update, final int delta);
+        
+        public boolean isEmpty();
+        
+        public int getCount(final Tuple update);
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/AdaptableMailbox.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/AdaptableMailbox.java
new file mode 100644
index 00000000..99097f56
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/AdaptableMailbox.java
@@ -0,0 +1,32 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2018, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.mailbox;
+
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationTracker;
+import tools.refinery.viatra.runtime.rete.network.communication.timely.TimelyMailboxProxy;
+import tools.refinery.viatra.runtime.rete.network.mailbox.timeless.BehaviorChangingMailbox;
+
+/**
+ * An adaptable mailbox can be wrapped by another mailbox to act in behalf of that. The significance of the adaptation
+ * is that the adaptee will notify the {@link CommunicationTracker} about updates by promoting the adapter itself.
+ * Adaptable mailboxes are used by the {@link BehaviorChangingMailbox}. 
+ * 
+ * Compare this with {@link TimelyMailboxProxy}. That one also wraps another mailbox in order to 
+ * perform preprocessing on the messages sent to the original recipient. 
+ * 
+ * @author Tamas Szabo
+ * @since 2.0
+ */
+public interface AdaptableMailbox extends Mailbox {
+
+    public Mailbox getAdapter();
+
+    public void setAdapter(final Mailbox adapter);
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/FallThroughCapableMailbox.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/FallThroughCapableMailbox.java
new file mode 100644
index 00000000..8797e254
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/FallThroughCapableMailbox.java
@@ -0,0 +1,30 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2019, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.mailbox;
+
+import tools.refinery.viatra.runtime.rete.network.Receiver;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationTracker;
+
+/**
+ * A fall through capable mailbox can directly call the update method of its {@link Receiver} instead of using the
+ * standard post-deliver mailbox semantics. If the fall through flag is set to true, the mailbox uses direct delivery,
+ * otherwise it operates in the original behavior. The fall through operation is preferable whenever applicable because
+ * it improves performance. The fall through flag is controlled by the {@link CommunicationTracker} based on the
+ * receiver node type and network topology.
+ * 
+ * @author Tamas Szabo
+ * @since 2.2
+ */
+public interface FallThroughCapableMailbox extends Mailbox {
+
+    public boolean isFallThrough();
+
+    public void setFallThrough(final boolean fallThrough);
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/Mailbox.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/Mailbox.java
new file mode 100644
index 00000000..05005974
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/Mailbox.java
@@ -0,0 +1,78 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2016, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.mailbox;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.util.Clearable;
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+import tools.refinery.viatra.runtime.rete.network.IGroupable;
+import tools.refinery.viatra.runtime.rete.network.Receiver;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationGroup;
+import tools.refinery.viatra.runtime.rete.network.communication.MessageSelector;
+import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
+
+/**
+ * A mailbox is associated with every {@link Receiver}. Messages can be sent to a {@link Receiver} by posting them into
+ * the mailbox. Different mailbox implementations may differ in the way how they deliver the posted messages.
+ * 
+ * @author Tamas Szabo
+ * @since 2.0
+ *
+ */
+public interface Mailbox extends Clearable, IGroupable {
+
+    /**
+     * Posts a new message to this mailbox.
+     * 
+     * @param direction
+     *            the direction of the update
+     * @param update
+     *            the update element
+     * @since 2.4
+     */
+    public void postMessage(final Direction direction, final Tuple update, final Timestamp timestamp);
+
+    /**
+     * Delivers all messages according to the given selector from this mailbox. The selector can also be null. In this case, no
+     * special separation is expected between the messages.
+     * 
+     * @param selector the message selector
+     */
+    public void deliverAll(final MessageSelector selector);
+
+    /**
+     * Returns the {@link Receiver} of this mailbox.
+     * 
+     * @return the receiver
+     */
+    public Receiver getReceiver();
+
+    /**
+     * Returns the {@link CommunicationGroup} of the receiver of this mailbox.
+     * 
+     * @return the communication group
+     */
+    public CommunicationGroup getCurrentGroup();
+
+    /**
+     * Sets the {@link CommunicationGroup} that the receiver of this mailbox is associated with.
+     * 
+     * @param group
+     *            the communication group
+     */
+    public void setCurrentGroup(final CommunicationGroup group);
+
+    /**
+     * Returns true if this mailbox is empty.
+     * 
+     * @return
+     */
+    public boolean isEmpty();
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/MessageIndexerFactory.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/MessageIndexerFactory.java
new file mode 100644
index 00000000..2c5255fb
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/MessageIndexerFactory.java
@@ -0,0 +1,23 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2018, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.mailbox;
+
+import tools.refinery.viatra.runtime.rete.network.indexer.MessageIndexer;
+
+/**
+ * A factory used to create message indexers for {@link Mailbox}es.
+ * 
+ * @author Tamas Szabo
+ * @since 2.0
+ */
+public interface MessageIndexerFactory<I extends MessageIndexer> {
+
+    public I create();
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timeless/AbstractUpdateSplittingMailbox.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timeless/AbstractUpdateSplittingMailbox.java
new file mode 100644
index 00000000..1e1ada71
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timeless/AbstractUpdateSplittingMailbox.java
@@ -0,0 +1,109 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2018, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.mailbox.timeless;
+
+import tools.refinery.viatra.runtime.rete.network.Receiver;
+import tools.refinery.viatra.runtime.rete.network.ReteContainer;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationGroup;
+import tools.refinery.viatra.runtime.rete.network.indexer.MessageIndexer;
+import tools.refinery.viatra.runtime.rete.network.mailbox.Mailbox;
+import tools.refinery.viatra.runtime.rete.network.mailbox.MessageIndexerFactory;
+
+/**
+ * An abstract mailbox implementation that is capable of splitting update messages based on some form of monotonicity
+ * (anti-monotone and monotone). The monotonicity is either defined by the less or equal operator of a poset or, it can
+ * be the standard subset ordering among sets of tuples.
+ * 
+ * @author Tamas Szabo
+ * @since 2.0
+ *
+ */
+public abstract class AbstractUpdateSplittingMailbox<IndexerType extends MessageIndexer, ReceiverType extends Receiver> implements Mailbox {
+
+    protected IndexerType monotoneQueue;
+    protected IndexerType antiMonotoneQueue;
+    protected IndexerType monotoneBuffer;
+    protected IndexerType antiMonotoneBuffer;
+    protected boolean deliveringMonotone;
+    protected boolean deliveringAntiMonotone;
+    protected final ReceiverType receiver;
+    protected final ReteContainer container;
+    protected CommunicationGroup group;
+
+    public AbstractUpdateSplittingMailbox(final ReceiverType receiver, final ReteContainer container,
+            final MessageIndexerFactory<IndexerType> factory) {
+        this.receiver = receiver;
+        this.container = container;
+        this.monotoneQueue = factory.create();
+        this.antiMonotoneQueue = factory.create();
+        this.monotoneBuffer = factory.create();
+        this.antiMonotoneBuffer = factory.create();
+        this.deliveringMonotone = false;
+        this.deliveringAntiMonotone = false;
+    }
+
+    protected void swapAndClearMonotone() {
+        final IndexerType tmp = this.monotoneQueue;
+        this.monotoneQueue = this.monotoneBuffer;
+        this.monotoneBuffer = tmp;
+        this.monotoneBuffer.clear();
+    }
+
+    protected void swapAndClearAntiMonotone() {
+        final IndexerType tmp = this.antiMonotoneQueue;
+        this.antiMonotoneQueue = this.antiMonotoneBuffer;
+        this.antiMonotoneBuffer = tmp;
+        this.antiMonotoneBuffer.clear();
+    }
+
+    protected IndexerType getActiveMonotoneQueue() {
+        if (this.deliveringMonotone) {
+            return this.monotoneBuffer;
+        } else {
+            return this.monotoneQueue;
+        }
+    }
+
+    protected IndexerType getActiveAntiMonotoneQueue() {
+        if (this.deliveringAntiMonotone) {
+            return this.antiMonotoneBuffer;
+        } else {
+            return this.antiMonotoneQueue;
+        }
+    }
+
+    @Override
+    public ReceiverType getReceiver() {
+        return this.receiver;
+    }
+
+    @Override
+    public void clear() {
+        this.monotoneQueue.clear();
+        this.antiMonotoneQueue.clear();
+        this.monotoneBuffer.clear();
+        this.antiMonotoneBuffer.clear();
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return this.getActiveMonotoneQueue().isEmpty() && this.getActiveAntiMonotoneQueue().isEmpty();
+    }
+
+    @Override
+    public CommunicationGroup getCurrentGroup() {
+        return this.group;
+    }
+
+    @Override
+    public void setCurrentGroup(final CommunicationGroup group) {
+        this.group = group;
+    }
+    
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timeless/BehaviorChangingMailbox.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timeless/BehaviorChangingMailbox.java
new file mode 100644
index 00000000..fe822d7c
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timeless/BehaviorChangingMailbox.java
@@ -0,0 +1,117 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2016, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.mailbox.timeless;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+import tools.refinery.viatra.runtime.rete.network.Node;
+import tools.refinery.viatra.runtime.rete.network.Receiver;
+import tools.refinery.viatra.runtime.rete.network.ReteContainer;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationGroup;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationTracker;
+import tools.refinery.viatra.runtime.rete.network.communication.MessageSelector;
+import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
+import tools.refinery.viatra.runtime.rete.network.communication.timeless.TimelessCommunicationTracker;
+import tools.refinery.viatra.runtime.rete.network.mailbox.AdaptableMailbox;
+import tools.refinery.viatra.runtime.rete.network.mailbox.FallThroughCapableMailbox;
+
+/**
+ * This mailbox changes its behavior based on the position of its {@link Receiver} in the network topology. 
+ * It either behaves as a {@link DefaultMailbox} or as an {@link UpdateSplittingMailbox}. The decision is made by the
+ * {@link CommunicationTracker}, see {@link TimelessCommunicationTracker#postProcessNode(Node)} for more details.
+ * 
+ * @author Tamas Szabo
+ */
+public class BehaviorChangingMailbox implements FallThroughCapableMailbox {
+
+    protected boolean fallThrough;
+    protected boolean split;
+    protected AdaptableMailbox wrapped;
+    protected final Receiver receiver;
+    protected final ReteContainer container;
+    protected CommunicationGroup group;
+
+    public BehaviorChangingMailbox(final Receiver receiver, final ReteContainer container) {
+        this.fallThrough = false;
+        this.split = false;
+        this.receiver = receiver;
+        this.container = container;
+        this.wrapped = new DefaultMailbox(receiver, container);
+        this.wrapped.setAdapter(this);
+    }
+
+    @Override
+    public void postMessage(final Direction direction, final Tuple update, final Timestamp timestamp) {
+        if (this.fallThrough && !this.container.isExecutingDelayedCommands()) {
+            // disable fall through while we are in the middle of executing delayed construction commands
+            this.receiver.update(direction, update, timestamp);
+        } else {
+            this.wrapped.postMessage(direction, update, timestamp);
+        }
+    }
+
+    @Override
+    public void deliverAll(final MessageSelector kind) {
+        this.wrapped.deliverAll(kind);
+    }
+
+    @Override
+    public String toString() {
+        return "A_MBOX -> " + this.wrapped;
+    }
+
+    public void setSplitFlag(final boolean splitValue) {
+        if (this.split != splitValue) {
+            assert isEmpty();
+            if (splitValue) {
+                this.wrapped = new UpdateSplittingMailbox(this.receiver, this.container);
+            } else {
+                this.wrapped = new DefaultMailbox(this.receiver, this.container);
+            }
+            this.wrapped.setAdapter(this);
+            this.split = splitValue;
+        }
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return this.wrapped.isEmpty();
+    }
+
+    @Override
+    public void clear() {
+        this.wrapped.clear();
+    }
+
+    @Override
+    public Receiver getReceiver() {
+        return this.receiver;
+    }
+    
+    @Override
+    public CommunicationGroup getCurrentGroup() {
+        return this.group;
+    }
+
+    @Override
+    public void setCurrentGroup(final CommunicationGroup group) {
+        this.group = group;
+    }
+
+    @Override
+    public boolean isFallThrough() {
+        return this.fallThrough;
+    }
+    
+    @Override
+    public void setFallThrough(final boolean fallThrough) {
+        this.fallThrough = fallThrough;
+    }
+    
+}
\ No newline at end of file
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timeless/DefaultMailbox.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timeless/DefaultMailbox.java
new file mode 100644
index 00000000..baf7270f
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timeless/DefaultMailbox.java
@@ -0,0 +1,163 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2016, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.mailbox.timeless;
+
+import java.util.Map;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.util.CollectionsFactory;
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+import tools.refinery.viatra.runtime.rete.network.Receiver;
+import tools.refinery.viatra.runtime.rete.network.ReteContainer;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationGroup;
+import tools.refinery.viatra.runtime.rete.network.communication.MessageSelector;
+import tools.refinery.viatra.runtime.rete.network.communication.PhasedSelector;
+import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
+import tools.refinery.viatra.runtime.rete.network.mailbox.AdaptableMailbox;
+import tools.refinery.viatra.runtime.rete.network.mailbox.Mailbox;
+
+/**
+ * Default mailbox implementation.
+ * <p>
+ * Usually, the mailbox performs counting of messages so that they can cancel each other out. However, if marked as a
+ * fall-through mailbox, than update messages are delivered directly to the receiver node to reduce overhead.
+ *
+ * @author Tamas Szabo
+ * @since 2.0
+ */
+public class DefaultMailbox implements AdaptableMailbox {
+
+    private static int SIZE_TRESHOLD = 127;
+
+    protected Map<Tuple, Integer> queue;
+    protected Map<Tuple, Integer> buffer;
+    protected final Receiver receiver;
+    protected final ReteContainer container;
+    protected boolean delivering;
+    protected Mailbox adapter;
+    protected CommunicationGroup group;
+
+    public DefaultMailbox(final Receiver receiver, final ReteContainer container) {
+        this.receiver = receiver;
+        this.container = container;
+        this.queue = CollectionsFactory.createMap();
+        this.buffer = CollectionsFactory.createMap();
+        this.adapter = this;
+    }
+
+    protected Map<Tuple, Integer> getActiveQueue() {
+        if (this.delivering) {
+            return this.buffer;
+        } else {
+            return this.queue;
+        }
+    }
+
+    @Override
+    public Mailbox getAdapter() {
+        return this.adapter;
+    }
+
+    @Override
+    public void setAdapter(final Mailbox adapter) {
+        this.adapter = adapter;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return getActiveQueue().isEmpty();
+    }
+
+    @Override
+    public void postMessage(final Direction direction, final Tuple update, final Timestamp timestamp) {
+        final Map<Tuple, Integer> activeQueue = getActiveQueue();
+        final boolean wasEmpty = activeQueue.isEmpty();
+
+        boolean significantChange = false;
+        Integer count = activeQueue.get(update);
+        if (count == null) {
+            count = 0;
+            significantChange = true;
+        }
+
+        if (direction == Direction.DELETE) {
+            count--;
+        } else {
+            count++;
+        }
+
+        if (count == 0) {
+            activeQueue.remove(update);
+            significantChange = true;
+        } else {
+            activeQueue.put(update, count);
+        }
+
+        if (significantChange) {
+            final Mailbox targetMailbox = this.adapter;
+            final CommunicationGroup targetGroup = this.adapter.getCurrentGroup();
+
+            if (wasEmpty) {
+                targetGroup.notifyHasMessage(targetMailbox, PhasedSelector.DEFAULT);
+            } else if (activeQueue.isEmpty()) {
+                targetGroup.notifyLostAllMessages(targetMailbox, PhasedSelector.DEFAULT);
+            }
+        }
+    }
+
+    @Override
+    public void deliverAll(final MessageSelector kind) {
+        if (kind == PhasedSelector.DEFAULT) {
+            // use the buffer during delivering so that there is a clear
+            // separation between the stages
+            this.delivering = true;
+            this.receiver.batchUpdate(this.queue.entrySet(), Timestamp.ZERO);
+            this.delivering = false;
+
+            if (queue.size() > SIZE_TRESHOLD) {
+                this.queue = this.buffer;
+                this.buffer = CollectionsFactory.createMap();
+            } else {
+                this.queue.clear();
+                final Map<Tuple, Integer> tmpQueue = this.queue;
+                this.queue = this.buffer;
+                this.buffer = tmpQueue;
+            }
+        } else {
+            throw new IllegalArgumentException("Unsupported message kind " + kind);
+        }
+    }
+
+    @Override
+    public String toString() {
+        return "D_MBOX (" + this.receiver + ") " + this.getActiveQueue();
+    }
+
+    @Override
+    public Receiver getReceiver() {
+        return this.receiver;
+    }
+
+    @Override
+    public void clear() {
+        this.queue.clear();
+        this.buffer.clear();
+    }
+
+    @Override
+    public CommunicationGroup getCurrentGroup() {
+        return this.group;
+    }
+
+    @Override
+    public void setCurrentGroup(final CommunicationGroup group) {
+        this.group = group;
+    }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timeless/PosetAwareMailbox.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timeless/PosetAwareMailbox.java
new file mode 100644
index 00000000..50d19882
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timeless/PosetAwareMailbox.java
@@ -0,0 +1,218 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2016, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.mailbox.timeless;
+
+import java.util.HashSet;
+import java.util.Map.Entry;
+import java.util.Set;
+
+import tools.refinery.viatra.runtime.matchers.context.IPosetComparator;
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.tuple.TupleMask;
+import tools.refinery.viatra.runtime.matchers.util.CollectionsFactory;
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+import tools.refinery.viatra.runtime.rete.network.PosetAwareReceiver;
+import tools.refinery.viatra.runtime.rete.network.ReteContainer;
+import tools.refinery.viatra.runtime.rete.network.communication.MessageSelector;
+import tools.refinery.viatra.runtime.rete.network.communication.PhasedSelector;
+import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
+import tools.refinery.viatra.runtime.rete.network.indexer.GroupBasedMessageIndexer;
+
+/**
+ * A monotonicity aware mailbox implementation. The mailbox uses an {@link IPosetComparator} to identify if a pair of
+ * REVOKE - INSERT updates represent a monotone change pair. The mailbox is used by {@link PosetAwareReceiver}s.
+ * 
+ * @author Tamas Szabo
+ * @since 2.0
+ */
+public class PosetAwareMailbox extends AbstractUpdateSplittingMailbox<GroupBasedMessageIndexer, PosetAwareReceiver> {
+
+    protected final TupleMask groupMask;
+
+    public PosetAwareMailbox(final PosetAwareReceiver receiver, final ReteContainer container) {
+        super(receiver, container, () -> new GroupBasedMessageIndexer(receiver.getCoreMask()));
+        this.groupMask = receiver.getCoreMask();
+    }
+
+    @Override
+    public void postMessage(final Direction direction, final Tuple update, final Timestamp timestamp) {
+        final GroupBasedMessageIndexer monotoneQueue = getActiveMonotoneQueue();
+        final GroupBasedMessageIndexer antiMonotoneQueue = getActiveAntiMonotoneQueue();
+        final boolean wasPresentAsMonotone = monotoneQueue.getCount(update) != 0;
+        final boolean wasPresentAsAntiMonotone = antiMonotoneQueue.getCount(update) != 0;
+        final TupleMask coreMask = this.receiver.getCoreMask();
+
+        // it cannot happen that it was present in both
+        assert !(wasPresentAsMonotone && wasPresentAsAntiMonotone);
+
+        if (direction == Direction.INSERT) {
+            if (wasPresentAsAntiMonotone) {
+                // it was an anti-monotone one before
+                antiMonotoneQueue.insert(update);
+            } else {
+                // it was a monotone one before or did not exist at all
+                monotoneQueue.insert(update);
+
+                // if it was not present in the monotone queue before, then
+                // we need to check whether it makes REVOKE updates monotone
+                if (!wasPresentAsMonotone) {
+                    final Set<Tuple> counterParts = tryFindCounterPart(update, false, true);
+                    for (final Tuple counterPart : counterParts) {
+                        final int count = antiMonotoneQueue.getCount(counterPart);
+                        assert count < 0;
+                        antiMonotoneQueue.update(counterPart, -count);
+                        monotoneQueue.update(counterPart, count);
+                    }
+                }
+            }
+        } else {
+            if (wasPresentAsAntiMonotone) {
+                // it was an anti-monotone one before
+                antiMonotoneQueue.delete(update);
+            } else if (wasPresentAsMonotone) {
+                // it was a monotone one before
+                monotoneQueue.delete(update);
+
+                // and we need to check whether the monotone REVOKE updates
+                // still have a reinforcing counterpart
+                final Set<Tuple> candidates = new HashSet<Tuple>();
+                final Tuple key = coreMask.transform(update);
+                for (final Entry<Tuple, Integer> entry : monotoneQueue.getTuplesByGroup(key).entrySet()) {
+                    if (entry.getValue() < 0) {
+                        final Tuple candidate = entry.getKey();
+                        final Set<Tuple> counterParts = tryFindCounterPart(candidate, true, false);
+                        if (counterParts.isEmpty()) {
+                            // all of them are gone
+                            candidates.add(candidate);
+                        }
+                    }
+                }
+
+                // move the candidates from the monotone queue to the
+                // anti-monotone queue because they do not have a
+                // counterpart anymore
+                for (final Tuple candidate : candidates) {
+                    final int count = monotoneQueue.getCount(candidate);
+                    assert count < 0;
+                    monotoneQueue.update(candidate, -count);
+                    antiMonotoneQueue.update(candidate, count);
+                }
+            } else {
+                // it did not exist before
+                final Set<Tuple> counterParts = tryFindCounterPart(update, true, false);
+                if (counterParts.isEmpty()) {
+                    // there is no tuple that would make this update monotone
+                    antiMonotoneQueue.delete(update);
+                } else {
+                    // there is a reinforcing counterpart
+                    monotoneQueue.delete(update);
+                }
+            }
+        }
+
+        if (antiMonotoneQueue.isEmpty()) {
+            this.group.notifyLostAllMessages(this, PhasedSelector.ANTI_MONOTONE);
+        } else {
+            this.group.notifyHasMessage(this, PhasedSelector.ANTI_MONOTONE);
+        }
+
+        if (monotoneQueue.isEmpty()) {
+            this.group.notifyLostAllMessages(this, PhasedSelector.MONOTONE);
+        } else {
+            this.group.notifyHasMessage(this, PhasedSelector.MONOTONE);
+        }
+    }
+
+    protected Set<Tuple> tryFindCounterPart(final Tuple first, final boolean findPositiveCounterPart,
+            final boolean findAllCounterParts) {
+        final GroupBasedMessageIndexer monotoneQueue = getActiveMonotoneQueue();
+        final GroupBasedMessageIndexer antiMonotoneQueue = getActiveAntiMonotoneQueue();
+        final TupleMask coreMask = this.receiver.getCoreMask();
+        final TupleMask posetMask = this.receiver.getPosetMask();
+        final IPosetComparator posetComparator = this.receiver.getPosetComparator();
+        final Set<Tuple> result = CollectionsFactory.createSet();
+        final Tuple firstKey = coreMask.transform(first);
+        final Tuple firstValue = posetMask.transform(first);
+
+        if (findPositiveCounterPart) {
+            for (final Entry<Tuple, Integer> entry : monotoneQueue.getTuplesByGroup(firstKey).entrySet()) {
+                final Tuple secondValue = posetMask.transform(entry.getKey());
+                if (entry.getValue() > 0 && posetComparator.isLessOrEqual(firstValue, secondValue)) {
+                    result.add(entry.getKey());
+                    if (!findAllCounterParts) {
+                        return result;
+                    }
+                }
+            }
+        } else {
+            for (final Entry<Tuple, Integer> entry : antiMonotoneQueue.getTuplesByGroup(firstKey).entrySet()) {
+                final Tuple secondValue = posetMask.transform(entry.getKey());
+                if (posetComparator.isLessOrEqual(secondValue, firstValue)) {
+                    result.add(entry.getKey());
+                    if (!findAllCounterParts) {
+                        return result;
+                    }
+                }
+            }
+        }
+
+        return result;
+    }
+
+    @Override
+    public void deliverAll(final MessageSelector kind) {
+        if (kind == PhasedSelector.ANTI_MONOTONE) {
+            // use the buffer during delivering so that there is a clear
+            // separation between the stages
+            this.deliveringAntiMonotone = true;
+
+            for (final Tuple group : this.antiMonotoneQueue.getGroups()) {
+                for (final Entry<Tuple, Integer> entry : this.antiMonotoneQueue.getTuplesByGroup(group).entrySet()) {
+                    final Tuple update = entry.getKey();
+                    final int count = entry.getValue();
+                    assert count < 0;
+                    for (int i = 0; i < Math.abs(count); i++) {
+                        this.receiver.updateWithPosetInfo(Direction.DELETE, update, false);
+                    }
+                }
+            }
+
+            this.deliveringAntiMonotone = false;
+            swapAndClearAntiMonotone();
+        } else if (kind == PhasedSelector.MONOTONE) {
+            // use the buffer during delivering so that there is a clear
+            // separation between the stages
+            this.deliveringMonotone = true;
+
+            for (final Tuple group : this.monotoneQueue.getGroups()) {
+                for (final Entry<Tuple, Integer> entry : this.monotoneQueue.getTuplesByGroup(group).entrySet()) {
+                    final Tuple update = entry.getKey();
+                    final int count = entry.getValue();
+                    assert count != 0;
+                    final Direction direction = count < 0 ? Direction.DELETE : Direction.INSERT;
+                    for (int i = 0; i < Math.abs(count); i++) {
+                        this.receiver.updateWithPosetInfo(direction, update, true);
+                    }
+                }
+            }
+
+            this.deliveringMonotone = false;
+            swapAndClearMonotone();
+        } else {
+            throw new IllegalArgumentException("Unsupported message kind " + kind);
+        }
+    }
+
+    @Override
+    public String toString() {
+        return "PA_MBOX (" + this.receiver + ") " + this.getActiveMonotoneQueue() + " "
+                + this.getActiveAntiMonotoneQueue();
+    }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timeless/UpdateSplittingMailbox.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timeless/UpdateSplittingMailbox.java
new file mode 100644
index 00000000..afa155b2
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timeless/UpdateSplittingMailbox.java
@@ -0,0 +1,135 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2016, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.mailbox.timeless;
+
+import java.util.Map.Entry;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+import tools.refinery.viatra.runtime.rete.network.Receiver;
+import tools.refinery.viatra.runtime.rete.network.ReteContainer;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationGroup;
+import tools.refinery.viatra.runtime.rete.network.communication.MessageSelector;
+import tools.refinery.viatra.runtime.rete.network.communication.PhasedSelector;
+import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
+import tools.refinery.viatra.runtime.rete.network.indexer.DefaultMessageIndexer;
+import tools.refinery.viatra.runtime.rete.network.mailbox.AdaptableMailbox;
+import tools.refinery.viatra.runtime.rete.network.mailbox.Mailbox;
+
+/**
+ * A mailbox implementation that splits updates messages according to the standard subset ordering into anti-monotonic
+ * (deletions) and monotonic (insertions) updates.
+ * 
+ * @author Tamas Szabo
+ * @since 2.0
+ */
+public class UpdateSplittingMailbox extends AbstractUpdateSplittingMailbox<DefaultMessageIndexer, Receiver>
+        implements AdaptableMailbox {
+
+    protected Mailbox adapter;
+
+    public UpdateSplittingMailbox(final Receiver receiver, final ReteContainer container) {
+        super(receiver, container, DefaultMessageIndexer::new);
+        this.adapter = this;
+    }
+
+    @Override
+    public Mailbox getAdapter() {
+        return this.adapter;
+    }
+
+    @Override
+    public void setAdapter(final Mailbox adapter) {
+        this.adapter = adapter;
+    }
+
+    @Override
+    public void postMessage(final Direction direction, final Tuple update, final Timestamp timestamp) {
+        final DefaultMessageIndexer monotoneQueue = getActiveMonotoneQueue();
+        final DefaultMessageIndexer antiMonotoneQueue = getActiveAntiMonotoneQueue();
+        final boolean wasPresentAsMonotone = monotoneQueue.getCount(update) != 0;
+        final boolean wasPresentAsAntiMonotone = antiMonotoneQueue.getCount(update) != 0;
+
+        // it cannot happen that it was present in both
+        assert !(wasPresentAsMonotone && wasPresentAsAntiMonotone);
+
+        if (direction == Direction.INSERT) {
+            if (wasPresentAsAntiMonotone) {
+                // it was an anti-monotone one before
+                antiMonotoneQueue.insert(update);
+            } else {
+                // it was a monotone one before or did not exist at all
+                monotoneQueue.insert(update);
+            }
+        } else {
+            if (wasPresentAsMonotone) {
+                // it was a monotone one before
+                monotoneQueue.delete(update);
+            } else {
+                // it was an anti-monotone one before or did not exist at all
+                antiMonotoneQueue.delete(update);
+            }
+        }
+
+        final Mailbox targetMailbox = this.adapter;
+        final CommunicationGroup targetGroup = this.adapter.getCurrentGroup();
+
+        if (antiMonotoneQueue.isEmpty()) {
+            targetGroup.notifyLostAllMessages(targetMailbox, PhasedSelector.ANTI_MONOTONE);
+        } else {
+            targetGroup.notifyHasMessage(targetMailbox, PhasedSelector.ANTI_MONOTONE);
+        }
+
+        if (monotoneQueue.isEmpty()) {
+            targetGroup.notifyLostAllMessages(targetMailbox, PhasedSelector.MONOTONE);
+        } else {
+            targetGroup.notifyHasMessage(targetMailbox, PhasedSelector.MONOTONE);
+        }
+    }
+
+    @Override
+    public void deliverAll(final MessageSelector kind) {
+        if (kind == PhasedSelector.ANTI_MONOTONE) {
+            // deliver anti-monotone
+            this.deliveringAntiMonotone = true;
+            for (final Entry<Tuple, Integer> entry : this.antiMonotoneQueue.getTuples().entrySet()) {
+                final Tuple update = entry.getKey();
+                final int count = entry.getValue();
+                assert count < 0;
+                for (int i = 0; i < Math.abs(count); i++) {
+                    this.receiver.update(Direction.DELETE, update, Timestamp.ZERO);
+                }
+            }
+            this.deliveringAntiMonotone = false;
+            swapAndClearAntiMonotone();
+        } else if (kind == PhasedSelector.MONOTONE) {
+            // deliver monotone
+            this.deliveringMonotone = true;
+            for (final Entry<Tuple, Integer> entry : this.monotoneQueue.getTuples().entrySet()) {
+                final Tuple update = entry.getKey();
+                final int count = entry.getValue();
+                assert count > 0;
+                for (int i = 0; i < count; i++) {
+                    this.receiver.update(Direction.INSERT, update, Timestamp.ZERO);
+                }
+            }
+            this.deliveringMonotone = false;
+            swapAndClearMonotone();
+        } else {
+            throw new IllegalArgumentException("Unsupported message kind " + kind);
+        }
+    }
+
+    @Override
+    public String toString() {
+        return "US_MBOX (" + this.receiver + ") " + this.getActiveMonotoneQueue() + " "
+                + this.getActiveAntiMonotoneQueue();
+    }
+
+}
diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timely/TimelyMailbox.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timely/TimelyMailbox.java
new file mode 100644
index 00000000..bf3b8e14
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/network/mailbox/timely/TimelyMailbox.java
@@ -0,0 +1,150 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2016, Tamas Szabo, Istvan Rath and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package tools.refinery.viatra.runtime.rete.network.mailbox.timely;
+
+import java.util.Map;
+import java.util.TreeMap;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.util.CollectionsFactory;
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+import tools.refinery.viatra.runtime.rete.matcher.TimelyConfiguration.TimelineRepresentation;
+import tools.refinery.viatra.runtime.rete.network.Receiver;
+import tools.refinery.viatra.runtime.rete.network.ReteContainer;
+import tools.refinery.viatra.runtime.rete.network.communication.CommunicationGroup;
+import tools.refinery.viatra.runtime.rete.network.communication.MessageSelector;
+import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
+import tools.refinery.viatra.runtime.rete.network.communication.timely.ResumableNode;
+import tools.refinery.viatra.runtime.rete.network.mailbox.Mailbox;
+
+public class TimelyMailbox implements Mailbox {
+
+    protected TreeMap<Timestamp, Map<Tuple, Integer>> queue;
+    protected final Receiver receiver;
+    protected final ReteContainer container;
+    protected CommunicationGroup group;
+    protected boolean fallThrough;
+
+    public TimelyMailbox(final Receiver receiver, final ReteContainer container) {
+        this.receiver = receiver;
+        this.container = container;
+        this.queue = CollectionsFactory.createTreeMap();
+    }
+
+    protected TreeMap<Timestamp, Map<Tuple, Integer>> getActiveQueue() {
+        return this.queue;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return getActiveQueue().isEmpty();
+    }
+
+    @Override
+    public void postMessage(final Direction direction, final Tuple update, final Timestamp timestamp) {
+        final TreeMap<Timestamp, Map<Tuple, Integer>> activeQueue = getActiveQueue();
+
+        Map<Tuple, Integer> tupleMap = activeQueue.get(timestamp);
+        final boolean wasEmpty = tupleMap == null;
+        boolean significantChange = false;
+
+        if (tupleMap == null) {
+            tupleMap = CollectionsFactory.createMap();
+            activeQueue.put(timestamp, tupleMap);
+            significantChange = true;
+        }
+
+        Integer count = tupleMap.get(update);
+        if (count == null) {
+            count = 0;
+            significantChange = true;
+        }
+
+        if (direction == Direction.DELETE) {
+            count--;
+        } else {
+            count++;
+        }
+
+        if (count == 0) {
+            tupleMap.remove(update);
+            if (tupleMap.isEmpty()) {
+                activeQueue.remove(timestamp);
+            }
+            significantChange = true;
+        } else {
+            tupleMap.put(update, count);
+        }
+
+        if (significantChange) {
+            if (wasEmpty) {
+                this.group.notifyHasMessage(this, timestamp);
+            } else if (tupleMap.isEmpty()) {
+                final Timestamp resumableTimestamp = (this.receiver instanceof ResumableNode)
+                        ? ((ResumableNode) this.receiver).getResumableTimestamp()
+                        : null;
+                // check if there is folding left to do before unsubscribing just based on the message queue being empty
+                if (resumableTimestamp == null || resumableTimestamp.compareTo(timestamp) != 0) {
+                    this.group.notifyLostAllMessages(this, timestamp);
+                }
+            }
+        }
+    }
+
+    @Override
+    public void deliverAll(final MessageSelector selector) {
+        if (selector instanceof Timestamp) {
+            final Timestamp timestamp = (Timestamp) selector;
+            // REMOVE the tuples associated with the selector, dont just query them
+            final Map<Tuple, Integer> tupleMap = this.queue.remove(timestamp);
+
+            // tupleMap may be empty if we only have lazy folding to do
+            if (tupleMap != null) {
+                this.receiver.batchUpdate(tupleMap.entrySet(), timestamp);
+            }
+
+            if (this.container.getTimelyConfiguration()
+                    .getTimelineRepresentation() == TimelineRepresentation.FAITHFUL) {
+                // (1) either normal delivery, which ended up being a lazy folding state
+                // (2) and/or lazy folding needs to be resumed
+                if (this.receiver instanceof ResumableNode) {
+                    ((ResumableNode) this.receiver).resumeAt(timestamp);
+                }
+            }
+        } else {
+            throw new IllegalArgumentException("Unsupported message selector " + selector);
+        }
+    }
+
+    @Override
+    public String toString() {
+        return "DDF_MBOX (" + this.receiver + ") " + this.getActiveQueue();
+    }
+
+    @Override
+    public Receiver getReceiver() {
+        return this.receiver;
+    }
+
+    @Override
+    public void clear() {
+        this.queue.clear();
+    }
+
+    @Override
+    public CommunicationGroup getCurrentGroup() {
+        return this.group;
+    }
+
+    @Override
+    public void setCurrentGroup(final CommunicationGroup group) {
+        this.group = group;
+    }
+
+}