diff --git a/src/main/java/net/onrc/onos/ofcontroller/topology/ITopologyNetService.java b/src/main/java/net/onrc/onos/ofcontroller/topology/ITopologyNetService.java
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+++ b/src/main/java/net/onrc/onos/ofcontroller/topology/ITopologyNetService.java
@@ -0,0 +1,90 @@
+package net.onrc.onos.ofcontroller.topology;
+
+import java.util.Map;
+
+import net.floodlightcontroller.core.module.IFloodlightService;
+import net.onrc.onos.ofcontroller.util.DataPath;
+import net.onrc.onos.ofcontroller.util.SwitchPort;
+
+/**
+ * Interface for providing Topology Network Service to other modules.
+ */
+public interface ITopologyNetService extends IFloodlightService {
+    /**
+     * Get the shortest path from a source to a destination.
+     *
+     * @param src the source in the shortest path computation.
+     * @param dest the destination in the shortest path computation.
+     * @return the data path with the computed shortest path if
+     * found, otherwise null.
+     */
+    DataPath getShortestPath(SwitchPort src, SwitchPort dest);
+
+    /**
+     * Fetch the Switch and Ports info from the Titan Graph
+     * and return it for fast access during the shortest path
+     * computation.
+     *
+     * After fetching the state, method @ref getTopoShortestPath()
+     * can be used for fast shortest path computation.
+     *
+     * Note: There is certain cost to fetch the state, hence it should
+     * be used only when there is a large number of shortest path
+     * computations that need to be done on the same topology.
+     * Typically, a single call to @ref prepareShortestPathTopo()
+     * should be followed by a large number of calls to
+     * method @ref getTopoShortestPath().
+     * After the last @ref getTopoShortestPath() call,
+     * method @ref dropShortestPathTopo() should be used to release
+     * the internal state that is not needed anymore:
+     *
+     *       Map<Long, ?> shortestPathTopo;
+     *       shortestPathTopo = prepareShortestPathTopo();
+     *       for (int i = 0; i < 10000; i++) {
+     *           dataPath = getTopoShortestPath(shortestPathTopo, ...);
+     *           ...
+     *        }
+     *        dropShortestPathTopo(shortestPathTopo);
+     *
+     * @return the Shortest Path info handler stored in a map.
+     */
+    Map<Long, ?> prepareShortestPathTopo();
+
+    /**
+     * Release the state that was populated by
+     * method @ref prepareShortestPathTopo().
+     *
+     * See the documentation for method @ref prepareShortestPathTopo()
+     * for additional information and usage.
+     *
+     * @param shortestPathTopo the Shortest Path info handler to release.
+     */
+    void dropShortestPathTopo(Map<Long, ?> shortestPathTopo);
+
+    /**
+     * Get the shortest path from a source to a destination by
+     * using the pre-populated local topology state prepared
+     * by method @ref prepareShortestPathTopo().
+     *
+     * See the documentation for method @ref prepareShortestPathTopo()
+     * for additional information and usage.
+     *
+     * @param shortestPathTopo the Shortest Path info handler
+     * to use.
+     * @param src the source in the shortest path computation.
+     * @param dest the destination in the shortest path computation.
+     * @return the data path with the computed shortest path if
+     * found, otherwise null.
+     */
+    DataPath getTopoShortestPath(Map<Long, ?> shortestPathTopo,
+				 SwitchPort src, SwitchPort dest);
+
+    /**
+     * Test whether a route exists from a source to a destination.
+     *
+     * @param src the source node for the test.
+     * @param dest the destination node for the test.
+     * @return true if a route exists, otherwise false.
+     */
+    Boolean routeExists(SwitchPort src, SwitchPort dest);
+}