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diff --git a/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/tabular/TabularIndexHost.java b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/tabular/TabularIndexHost.java
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+++ b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/tabular/TabularIndexHost.java
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+/*******************************************************************************
+ * Copyright (c) 2010-2018, Gabor Bergmann, IncQuery Labs 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.tabular;
+
+import tools.refinery.viatra.runtime.api.ViatraQueryEngine;
+import tools.refinery.viatra.runtime.api.scope.IEngineContext;
+import tools.refinery.viatra.runtime.api.scope.IIndexingErrorListener;
+import tools.refinery.viatra.runtime.api.scope.QueryScope;
+import tools.refinery.viatra.runtime.matchers.context.IInputKey;
+import tools.refinery.viatra.runtime.matchers.scopes.IStorageBackend;
+import tools.refinery.viatra.runtime.matchers.scopes.TabularRuntimeContext;
+import tools.refinery.viatra.runtime.matchers.scopes.tables.IIndexTable;
+import tools.refinery.viatra.runtime.matchers.scopes.tables.ITableWriterBinary;
+import tools.refinery.viatra.runtime.matchers.scopes.tables.ITableWriterUnary;
+
+/**
+ * Simple tabular index host. 
+ * 
+ * Unlike traditional Viatra instances initialized on a model, 
+ *  this index host can be initialized and then queried, 
+ *  while its queriable "contents" (base relations) can be separately written using table writer API. 
+ *  
+ * <p> Deriving classes are responsible for setting up the tables of this index and providing the writer API to clients.
+ *  For the former, use {@link #newUnaryInputTable(IInputKey, boolean)}, 
+ *  {@link #newBinaryInputTable(IInputKey, boolean)} to create input tables, 
+ *  or {@link #registerNewTable(IIndexTable)} to register manually created derived tables. 
+ *  Instantiate such tables with {@link #runtimeContext} as their table context.
+ *  
+ * 
+ * <p>
+ * <strong>EXPERIMENTAL</strong>. This class or interface has been added as
+ * part of a work in progress. There is no guarantee that this API will
+ * work or that it will remain the same.
+ *
+ * @see EcoreIndexHost EcoreIndexHost for EMF-specific example usage.
+ * 
+ * @author Gabor Bergmann
+ * @since 2.1
+ */
+public abstract class TabularIndexHost {
+    
+    private final IStorageBackend storage;
+    protected final TabularRuntimeContext runtimeContext;
+    protected final TabularIndexScope scope = new TabularIndexScope();
+
+    public TabularIndexHost(IStorageBackend storage, TabularRuntimeContext runtimeContext) {
+        this.storage = storage;
+        this.runtimeContext = runtimeContext;
+    }
+
+
+    public TabularRuntimeContext getRuntimeContext() {
+        return runtimeContext;
+    }
+
+    public TabularIndexScope getScope() {
+        return scope;
+    }
+    
+    /**
+     * @return true if this index host aims to serve queries that have a scope of the given type
+     */
+    protected abstract boolean isQueryScopeEmulated(Class<? extends QueryScope> queryScopeClass);
+
+    
+    
+    /**
+     * Marks the beginning of an update transaction.
+     * In transaction mode, index table updates may be temporarily delayed for better performance. 
+     * Stateful query backends will not update their results during the index update transaction. (TODO actually achieve this)
+     */
+    public void startUpdateTransaction() {
+        storage.startTransaction();
+    }
+    /**
+     * Marks the end of an update transaction.
+     * Any updates to index tables that were delayed during the transaction must now be flushed. 
+     * Afterwards, stateful query backends will update their results. (TODO actually achieve this)
+     */
+    public void finishUpdateTransaction() {
+        storage.finishTransaction();
+    }
+    
+    /**
+     * To be called by deriving class. Creates and registers a new unary input table.
+     */
+    protected ITableWriterUnary.Table<Object> newUnaryInputTable(IInputKey key, boolean unique) {
+        return registerNewTable(storage.createUnaryTable(key, runtimeContext, unique));
+    }
+    /**
+     * To be called by deriving class. Creates and registers a new binary input table.
+     */
+    protected ITableWriterBinary.Table<Object,Object> newBinaryInputTable(IInputKey key, boolean unique) {
+        return registerNewTable(storage.createBinaryTable(key, runtimeContext, unique));
+    }
+    /**
+     * To be called by deriving class. Registers the given freshly created table and also returns it for convenience.
+     */
+    protected <Table extends IIndexTable> Table registerNewTable(Table newTable) {
+        runtimeContext.registerIndexTable(newTable);
+        return newTable;
+    }
+
+
+    /**
+     * A scope describing queries evaluated against tzhis index host.
+     * @author Gabor Bergmann
+     *
+     */
+    public class TabularIndexScope extends QueryScope {
+        
+        public TabularIndexHost getIndexHost() {
+            return TabularIndexHost.this;
+        }
+        
+        @Override
+        public int hashCode() {
+            return getIndexHost().hashCode();
+        }
+        
+        @Override
+        public boolean equals(Object obj) {
+            if (obj instanceof TabularIndexScope)
+                return getIndexHost().equals(((TabularIndexScope) obj).getIndexHost());
+            return false;
+        }
+        
+        @Override
+        public boolean isCompatibleWithQueryScope(Class<? extends QueryScope> queryScopeClass) {
+            return isQueryScopeEmulated(queryScopeClass) || super.isCompatibleWithQueryScope(queryScopeClass);
+        }
+        
+        @Override
+        protected IEngineContext createEngineContext(ViatraQueryEngine engine, IIndexingErrorListener errorListener, org.apache.log4j.Logger logger) {
+            return new TabularEngineContext(getIndexHost(), engine, errorListener, logger);
+        }
+
+    }
+}