diff --git a/src/main/java/net/onrc/onos/ofcontroller/topology/ITopologyNetService.java b/src/main/java/net/onrc/onos/ofcontroller/topology/ITopologyNetService.java
index bd0ca38..9585366 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/topology/ITopologyNetService.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/topology/ITopologyNetService.java
@@ -11,73 +11,72 @@
  */
 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()
+     * After fetching the state, method @ref getTopologyShortestPath()
      * 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()
+     * Typically, a single call to @ref newDatabaseTopology()
      * 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
+     * method @ref getTopologyShortestPath().
+     * After the last @ref getTopologyShortestPath() call,
+     * method @ref dropTopology() should be used to release
      * the internal state that is not needed anymore:
      *
-     *       Map<Long, ?> shortestPathTopo;
-     *       shortestPathTopo = prepareShortestPathTopo();
+     *       Topology topology = topologyManager.newDatabaseTopology();
      *       for (int i = 0; i < 10000; i++) {
-     *           dataPath = getTopoShortestPath(shortestPathTopo, ...);
+     *           dataPath = topologyManager.getTopologyShortestPath(topology, ...);
      *           ...
      *        }
-     *        dropShortestPathTopo(shortestPathTopo);
+     *        topologyManager.dropTopology(shortestPathTopo);
      *
-     * @return the Shortest Path info handler stored in a map.
+     * @return the allocated topology handler.
      */
-    Map<Long, ?> prepareShortestPathTopo();
+    Topology newDatabaseTopology();
 
     /**
-     * Release the state that was populated by
-     * method @ref prepareShortestPathTopo().
+     * Release the topology that was populated by
+     * method @ref newDatabaseTopology().
      *
-     * See the documentation for method @ref prepareShortestPathTopo()
+     * See the documentation for method @ref newDatabaseTopology()
      * for additional information and usage.
      *
-     * @param shortestPathTopo the Shortest Path info handler to release.
+     * @param topology the topology to release.
      */
-    void dropShortestPathTopo(Map<Long, ?> shortestPathTopo);
+    void dropTopology(Topology topology);
 
     /**
      * Get the shortest path from a source to a destination by
      * using the pre-populated local topology state prepared
-     * by method @ref prepareShortestPathTopo().
+     * by method @ref newDatabaseTopology().
      *
-     * See the documentation for method @ref prepareShortestPathTopo()
+     * See the documentation for method @ref newDatabaseTopology()
      * for additional information and usage.
      *
-     * @param shortestPathTopo the Shortest Path info handler
-     * to use.
+     * @param topology the topology 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);
+    DataPath getTopologyShortestPath(Topology topology,
+				     SwitchPort src, SwitchPort dest);
+
+    /**
+     * Get the shortest path from a source to a destination by using
+     * the underlying database.
+     *
+     * @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 getDatabaseShortestPath(SwitchPort src, SwitchPort dest);
 
     /**
      * Test whether a route exists from a source to a destination.
diff --git a/src/main/java/net/onrc/onos/ofcontroller/topology/ShortestPath.java b/src/main/java/net/onrc/onos/ofcontroller/topology/ShortestPath.java
new file mode 100644
index 0000000..1133d3d
--- /dev/null
+++ b/src/main/java/net/onrc/onos/ofcontroller/topology/ShortestPath.java
@@ -0,0 +1,325 @@
+package net.onrc.onos.ofcontroller.topology;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Queue;
+import java.util.Set;
+
+import net.onrc.onos.graph.GraphDBOperation;
+import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.ISwitchObject;
+import net.onrc.onos.ofcontroller.core.ISwitchStorage.SwitchState;
+import net.onrc.onos.ofcontroller.util.DataPath;
+import net.onrc.onos.ofcontroller.util.Dpid;
+import net.onrc.onos.ofcontroller.util.FlowEntry;
+import net.onrc.onos.ofcontroller.util.Port;
+import net.onrc.onos.ofcontroller.util.SwitchPort;
+
+import org.openflow.util.HexString;
+
+import com.tinkerpop.blueprints.Direction;
+import com.tinkerpop.blueprints.Vertex;
+
+/**
+ * A class for implementing the Shortest Path in a topology.
+ */
+public class ShortestPath {
+    /**
+     * Get the shortest path from a source to a destination by
+     * using the pre-populated local topology state prepared
+     * by method @ref TopologyManager.newDatabaseTopology().
+     *
+     * For additional documentation and usage, see method
+     * @ref TopologyManager.newDatabaseTopology()
+     *
+     * @param topology the topology 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.
+     */
+    public static DataPath getTopologyShortestPath(
+		Topology topology,
+		SwitchPort src, SwitchPort dest) {
+	DataPath result_data_path = new DataPath();
+
+	// Initialize the source and destination in the data path to return
+	result_data_path.setSrcPort(src);
+	result_data_path.setDstPort(dest);
+
+	String dpid_src = src.dpid().toString();
+	String dpid_dest = dest.dpid().toString();
+
+	// Get the source vertex
+	Node v_src = topology.getNode(src.dpid().value());
+	if (v_src == null) {
+	    return null;		// Source vertex not found
+	}
+
+	// Get the destination vertex
+	Node v_dest = topology.getNode(dest.dpid().value());
+	if (v_dest == null) {
+	    return null;		// Destination vertex not found
+	}
+
+	//
+	// Test whether we are computing a path from/to the same DPID.
+	// If "yes", then just add a single flow entry in the return result.
+	//
+	if (dpid_src.equals(dpid_dest)) {
+	    FlowEntry flowEntry = new FlowEntry();
+	    flowEntry.setDpid(src.dpid());
+	    flowEntry.setInPort(src.port());
+	    flowEntry.setOutPort(dest.port());
+	    result_data_path.flowEntries().add(flowEntry);
+	    return result_data_path;
+	}
+
+	//
+	// Implement the Shortest Path computation by using Breath First Search
+	//
+	Set<Node> visitedSet = new HashSet<Node>();
+	Queue<Node> processingList = new LinkedList<Node>();
+	Map<Node, Node.Link> previousVertexMap = new HashMap<Node, Node.Link>();
+	processingList.add(v_src);
+	visitedSet.add(v_src);
+	Boolean path_found = false;
+	while (! processingList.isEmpty()) {
+	    Node nextVertex = processingList.poll();
+	    if (v_dest == nextVertex) {
+		path_found = true;
+		break;
+	    }
+	    for (Node.Link link : nextVertex.links.values()) {
+		Node child = link.neighbor;
+		if (! visitedSet.contains(child)) {
+		    previousVertexMap.put(child, link);
+		    visitedSet.add(child);
+		    processingList.add(child);
+		}
+	    }
+	}
+	if (! path_found)
+	    return null;		// No path found
+
+	// Collect the path as a list of links
+	List<Node.Link> resultPath = new LinkedList<Node.Link>();
+	Node previousVertex = v_dest;
+	while (! v_src.equals(previousVertex)) {
+	    Node.Link currentLink = previousVertexMap.get(previousVertex);
+	    resultPath.add(currentLink);
+	    previousVertex = currentLink.me;
+	}
+	Collections.reverse(resultPath);
+
+	//
+	// Loop through the result and prepare the return result
+	// as a list of Flow Entries.
+	//
+	Port inPort = new Port(src.port().value());
+	Port outPort;
+	for (Node.Link link: resultPath) {
+	    // Setup the outgoing port, and add the Flow Entry
+	    outPort = new Port(link.myPort);
+
+	    FlowEntry flowEntry = new FlowEntry();
+	    flowEntry.setDpid(new Dpid(link.me.nodeId));
+	    flowEntry.setInPort(inPort);
+	    flowEntry.setOutPort(outPort);
+	    result_data_path.flowEntries().add(flowEntry);
+
+	    // Setup the next incoming port
+	    inPort = new Port(link.neighborPort);
+	}
+	if (resultPath.size() > 0) {
+	    // Add the last Flow Entry
+	    FlowEntry flowEntry = new FlowEntry();
+	    flowEntry.setDpid(new Dpid(dest.dpid().value()));
+	    flowEntry.setInPort(inPort);
+	    flowEntry.setOutPort(dest.port());
+	    result_data_path.flowEntries().add(flowEntry);
+	}
+
+	if (result_data_path.flowEntries().size() > 0)
+	    return result_data_path;
+
+	return null;
+    }
+
+    /**
+     * Get the shortest path from a source to a destination by using
+     * the underlying Graph Database.
+     *
+     * @param dbHandler the Graph Database 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.
+     */
+    public static DataPath getDatabaseShortestPath(GraphDBOperation dbHandler,
+					     SwitchPort src, SwitchPort dest) {
+	DataPath result_data_path = new DataPath();
+
+	// Initialize the source and destination in the data path to return
+	result_data_path.setSrcPort(src);
+	result_data_path.setDstPort(dest);
+
+	String dpid_src = src.dpid().toString();
+	String dpid_dest = dest.dpid().toString();
+
+	// Get the source and destination switches
+	ISwitchObject srcSwitch =
+	    dbHandler.searchActiveSwitch(dpid_src);
+	ISwitchObject destSwitch =
+	    dbHandler.searchActiveSwitch(dpid_dest);
+	if (srcSwitch == null || destSwitch == null) {
+	    return null;
+	}
+
+	//
+	// Test whether we are computing a path from/to the same DPID.
+	// If "yes", then just add a single flow entry in the return result.
+	//
+	if (dpid_src.equals(dpid_dest)) {
+	    FlowEntry flowEntry = new FlowEntry();
+	    flowEntry.setDpid(src.dpid());
+	    flowEntry.setInPort(src.port());
+	    flowEntry.setOutPort(dest.port());
+	    result_data_path.flowEntries().add(flowEntry);
+	    dbHandler.commit();
+	    return result_data_path;
+	}
+
+	Vertex v_src = srcSwitch.asVertex();	
+	Vertex v_dest = destSwitch.asVertex();
+
+	//
+	// Implement the Shortest Path computation by using Breath First Search
+	//
+	Set<Vertex> visitedSet = new HashSet<Vertex>();
+	Queue<Vertex> processingList = new LinkedList<Vertex>();
+	Map<Vertex, Vertex> previousVertexMap = new HashMap<Vertex, Vertex>();
+
+	processingList.add(v_src);
+	visitedSet.add(v_src);
+	Boolean path_found = false;
+	while (! processingList.isEmpty()) {
+	    Vertex nextVertex = processingList.poll();
+	    if (v_dest.equals(nextVertex)) {
+		path_found = true;
+		break;
+	    }
+	    for (Vertex parentPort : nextVertex.getVertices(Direction.OUT, "on")) {
+		// Ignore inactive ports
+		if (! parentPort.getProperty("state").toString().equals("ACTIVE"))
+			continue;
+
+		for (Vertex childPort : parentPort.getVertices(Direction.OUT, "link")) {
+		    // Ignore inactive ports
+		    if (! childPort.getProperty("state").toString().equals("ACTIVE"))
+			continue;
+
+		    for (Vertex child : childPort.getVertices(Direction.IN, "on")) {
+			// Ignore inactive switches
+			String state = child.getProperty("state").toString();
+			if (! state.equals(SwitchState.ACTIVE.toString()))
+			    continue;
+
+			if (! visitedSet.contains(child)) {
+			    previousVertexMap.put(parentPort, nextVertex);
+			    previousVertexMap.put(childPort, parentPort);
+			    previousVertexMap.put(child, childPort);
+			    visitedSet.add(child);
+			    processingList.add(child);
+			}
+		    }
+		}
+	    }
+	}
+	if (! path_found)
+	    return null;		// No path found
+
+	List<Vertex> resultPath = new LinkedList<Vertex>();
+	Vertex previousVertex = v_dest;
+	resultPath.add(v_dest);
+	while (! v_src.equals(previousVertex)) {
+	    Vertex currentVertex = previousVertexMap.get(previousVertex);
+	    resultPath.add(currentVertex);
+	    previousVertex = currentVertex;
+	}
+	Collections.reverse(resultPath);
+
+
+	//
+	// Loop through the result and prepare the return result
+	// as a list of Flow Entries.
+	//
+	long nodeId = 0;
+	short portId = 0;
+	Port inPort = new Port(src.port().value());
+	Port outPort = new Port();
+	int idx = 0;
+	for (Vertex v: resultPath) {
+	    String type = v.getProperty("type").toString();
+	    // System.out.println("type: " + type);
+	    if (type.equals("port")) {
+		//String number = v.getProperty("number").toString();
+		// System.out.println("number: " + number);
+
+		Object obj = v.getProperty("number");
+		// String class_str = obj.getClass().toString();
+		if (obj instanceof Short) {
+		    portId = (Short)obj;
+		} else if (obj instanceof Integer) {
+		    Integer int_nodeId = (Integer)obj;
+		    portId = int_nodeId.shortValue();
+		    // int int_nodeId = (Integer)obj;
+		    // portId = (short)int_nodeId.;
+		}
+	    } else if (type.equals("switch")) {
+		String dpid = v.getProperty("dpid").toString();
+		nodeId = HexString.toLong(dpid);
+
+		// System.out.println("dpid: " + dpid);
+	    }
+	    idx++;
+	    if (idx == 1) {
+		continue;
+	    }
+	    int mod = idx % 3;
+	    if (mod == 0) {
+		// Setup the incoming port
+		inPort = new Port(portId);
+		continue;
+	    }
+	    if (mod == 2) {
+		// Setup the outgoing port, and add the Flow Entry
+		outPort = new Port(portId);
+
+		FlowEntry flowEntry = new FlowEntry();
+		flowEntry.setDpid(new Dpid(nodeId));
+		flowEntry.setInPort(inPort);
+		flowEntry.setOutPort(outPort);
+		result_data_path.flowEntries().add(flowEntry);
+		continue;
+	    }
+	}
+	if (idx > 0) {
+	    // Add the last Flow Entry
+	    FlowEntry flowEntry = new FlowEntry();
+	    flowEntry.setDpid(new Dpid(nodeId));
+	    flowEntry.setInPort(inPort);
+	    flowEntry.setOutPort(dest.port());
+	    result_data_path.flowEntries().add(flowEntry);
+	}
+
+	dbHandler.commit();
+	if (result_data_path.flowEntries().size() > 0)
+	    return result_data_path;
+
+	return null;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/net/onrc/onos/ofcontroller/topology/Topology.java b/src/main/java/net/onrc/onos/ofcontroller/topology/Topology.java
new file mode 100644
index 0000000..a2f2c21
--- /dev/null
+++ b/src/main/java/net/onrc/onos/ofcontroller/topology/Topology.java
@@ -0,0 +1,174 @@
+package net.onrc.onos.ofcontroller.topology;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import net.onrc.onos.graph.GraphDBOperation;
+import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.ISwitchObject;
+import net.onrc.onos.ofcontroller.core.ISwitchStorage.SwitchState;
+
+import org.openflow.util.HexString;
+
+import com.tinkerpop.blueprints.Direction;
+import com.tinkerpop.blueprints.Vertex;
+
+/**
+ * A class for storing Node and Link information for fast computation
+ * of shortest paths.
+ */
+class Node {
+    /**
+     * A class for storing Link information for fast computation of shortest
+     * paths.
+     */
+    class Link {
+	public Node me;			// The node this link originates from
+	public Node neighbor;		// The neighbor node on the other side
+	public short myPort;		// Local port number for the link
+	public short neighborPort;	// Neighbor port number for the link
+
+	/**
+	 * Link constructor.
+	 *
+	 * @param me the node this link originates from.
+	 * @param the neighbor node on the other side of the link.
+	 * @param myPort local port number for the link.
+	 * @param neighborPort neighrobr port number for the link.
+	 */
+	public Link(Node me, Node neighbor, short myPort, short neighborPort) {
+	    this.me = me;
+	    this.neighbor = neighbor;
+	    this.myPort = myPort;
+	    this.neighborPort = neighborPort;
+	}
+    };
+
+    public long nodeId;			// The node ID
+    public HashMap<Short, Link> links;	// The links originating from this node
+
+    /**
+     * Node constructor.
+     *
+     * @param nodeId the node ID.
+     */
+    public Node(long nodeId) {
+	this.nodeId = nodeId;
+	links = new HashMap<Short, Link>();
+    }
+
+    /**
+     * Add a neighbor.
+     *
+     * A new link to the neighbor will be created. 
+     *
+     * @param neighbor the neighbor to add.
+     * @param myPort the local port number for the link to the neighbor.
+     * @param neighborPort the neighbor port number for the link.
+     */
+    public void addNeighbor(Node neighbor, short myPort, short neighborPort) {
+	Link link = new Link(this, neighbor, myPort, neighborPort);
+	links.put(myPort, link);
+    }
+};
+
+/**
+ * A class for storing topology information.
+ */
+public class Topology {
+    private Map<Long, Node> nodesMap;	// The dpid->Node mapping
+
+    public Topology() {
+	nodesMap = new HashMap<Long, Node>();
+    }
+
+    /**
+     * Get a node for a give Node ID.
+     *
+     * @param nodeId the Node ID to use.
+     * @return the corresponding Node if found, otherwise null.
+     */
+    Node getNode(long nodeId) {
+	return nodesMap.get(nodeId);
+    }
+
+    /**
+     * Read topology state from the database.
+     *
+     * @param dbHandler the Graph Database handler to use.
+     */
+    public void readFromDatabase(GraphDBOperation dbHandler) {
+	//
+	// Fetch the relevant info from the Switch and Port vertices
+	// from the Titan Graph.
+	//
+	Iterable<ISwitchObject> activeSwitches = dbHandler.getActiveSwitches();
+	for (ISwitchObject switchObj : activeSwitches) {
+	    Vertex nodeVertex = switchObj.asVertex();
+	    //
+	    // The Switch info
+	    //
+	    String nodeDpid = nodeVertex.getProperty("dpid").toString();
+	    long nodeId = HexString.toLong(nodeDpid);
+	    Node me = nodesMap.get(nodeId);
+	    if (me == null) {
+		me = new Node(nodeId);
+		nodesMap.put(nodeId, me);
+	    }
+
+	    //
+	    // The local Port info
+	    //
+	    for (Vertex myPortVertex : nodeVertex.getVertices(Direction.OUT, "on")) {
+		// Ignore inactive ports
+		if (! myPortVertex.getProperty("state").toString().equals("ACTIVE"))
+		    continue;
+
+		short myPort = 0;
+		Object obj = myPortVertex.getProperty("number");
+		if (obj instanceof Short) {
+		    myPort = (Short)obj;
+		} else if (obj instanceof Integer) {
+		    Integer int_nodeId = (Integer)obj;
+		    myPort = int_nodeId.shortValue();
+		}
+
+		//
+		// The neighbor Port info
+		//
+		for (Vertex neighborPortVertex : myPortVertex.getVertices(Direction.OUT, "link")) {
+		    // Ignore inactive ports
+		    if (! neighborPortVertex.getProperty("state").toString().equals("ACTIVE"))
+			continue;
+
+		    short neighborPort = 0;
+		    obj = neighborPortVertex.getProperty("number");
+		    if (obj instanceof Short) {
+			neighborPort = (Short)obj;
+		    } else if (obj instanceof Integer) {
+			Integer int_nodeId = (Integer)obj;
+			neighborPort = int_nodeId.shortValue();
+		    }
+		    //
+		    // The neighbor Switch info
+		    //
+		    for (Vertex neighborVertex : neighborPortVertex.getVertices(Direction.IN, "on")) {
+			// Ignore inactive switches
+			String state = neighborVertex.getProperty("state").toString();
+			if (! state.equals(SwitchState.ACTIVE.toString()))
+			    continue;
+
+			String neighborDpid = neighborVertex.getProperty("dpid").toString();
+			long neighborId = HexString.toLong(neighborDpid);
+			Node neighbor = nodesMap.get(neighborId);
+			if (neighbor == null) {
+			    neighbor = new Node(neighborId);
+			    nodesMap.put(neighborId, neighbor);
+			}
+			me.addNeighbor(neighbor, myPort, neighborPort);
+		    }
+		}
+	    }
+	}
+	dbHandler.commit();
+    }
+}
diff --git a/src/main/java/net/onrc/onos/ofcontroller/topology/TopologyManager.java b/src/main/java/net/onrc/onos/ofcontroller/topology/TopologyManager.java
index a327ef9..c027998 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/topology/TopologyManager.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/topology/TopologyManager.java
@@ -37,65 +37,6 @@
 
 
 /**
- * A class for storing Node and Link information for fast computation
- * of shortest paths.
- */
-class Node {
-    /**
-     * A class for storing Link information for fast computation of shortest
-     * paths.
-     */
-    class Link {
-	public Node me;			// The node this link originates from
-	public Node neighbor;		// The neighbor node on the other side
-	public short myPort;		// Local port number for the link
-	public short neighborPort;	// Neighbor port number for the link
-
-	/**
-	 * Link constructor.
-	 *
-	 * @param me the node this link originates from.
-	 * @param the neighbor node on the other side of the link.
-	 * @param myPort local port number for the link.
-	 * @param neighborPort neighrobr port number for the link.
-	 */
-	public Link(Node me, Node neighbor, short myPort, short neighborPort) {
-	    this.me = me;
-	    this.neighbor = neighbor;
-	    this.myPort = myPort;
-	    this.neighborPort = neighborPort;
-	}
-    };
-
-    public long nodeId;			// The node ID
-    public HashMap<Short, Link> links;	// The links originating from this node
-
-    /**
-     * Node constructor.
-     *
-     * @param nodeId the node ID.
-     */
-    public Node(long nodeId) {
-	this.nodeId = nodeId;
-	links = new HashMap<Short, Link>();
-    }
-
-    /**
-     * Add a neighbor.
-     *
-     * A new link to the neighbor will be created. 
-     *
-     * @param neighbor the neighbor to add.
-     * @param myPort the local port number for the link to the neighbor.
-     * @param neighborPort the neighbor port number for the link.
-     */
-    public void addNeighbor(Node neighbor, short myPort, short neighborPort) {
-	Link link = new Link(this, neighbor, myPort, neighborPort);
-	links.put(myPort, link);
-    }
-};
-
-/**
  * A class for implementing Topology Network Service.
  */
 public class TopologyManager implements IFloodlightModule,
@@ -103,7 +44,7 @@
     private static Logger log = LoggerFactory.getLogger(TopologyManager.class);
     protected IFloodlightProviderService floodlightProvider;
 
-    protected GraphDBOperation op;
+    protected GraphDBOperation dbHandler;
 
 
     /**
@@ -125,11 +66,11 @@
     /**
      * Constructor for a given database operation handler.
      *
-     * @param handler the database operation handler to use for the
+     * @param dbHandler the database operation handler to use for the
      * initialization.
      */
-    public TopologyManager(GraphDBOperation handler) {
-	this.op = handler;
+    public TopologyManager(GraphDBOperation dbHandler) {
+	this.dbHandler = dbHandler;
     }
 
     /**
@@ -140,7 +81,7 @@
      */
     public void init(String config) {
 	try {
-	    op = new GraphDBOperation(config);
+	    dbHandler = new GraphDBOperation(config);
 	} catch (Exception e) {
 	    log.error(e.getMessage());
 	}
@@ -157,7 +98,7 @@
      * Close the service. It will close the corresponding database connection.
      */
     public void close() {
-	op.close();
+	dbHandler.close();
     }
 
     /**
@@ -234,248 +175,70 @@
      * and return it for fast access during the shortest path
      * computation.
      *
-     * After fetching the state, method @ref getTopoShortestPath()
+     * After fetching the state, method @ref getTopologyShortestPath()
      * 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()
+     * Typically, a single call to @ref newDatabaseTopology()
      * 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
+     * method @ref getTopologyShortestPath().
+     * After the last @ref getTopologyShortestPath() call,
+     * method @ref dropTopology() should be used to release
      * the internal state that is not needed anymore:
      *
-     *       Map<Long, ?> shortestPathTopo;
-     *       shortestPathTopo = prepareShortestPathTopo();
+     *       Topology topology = topologyManager.newDatabaseTopology();
      *       for (int i = 0; i < 10000; i++) {
-     *           dataPath = getTopoShortestPath(shortestPathTopo, ...);
+     *           dataPath = topologyManager.getTopologyShortestPath(topology, ...);
      *           ...
      *        }
-     *        dropShortestPathTopo(shortestPathTopo);
+     *        topologyManager.dropTopology(shortestPathTopo);
      *
-     * @return the Shortest Path info handler stored in a map.
+     * @return the allocated topology handler.
      */
-    public Map<Long, ?> prepareShortestPathTopo() {
-	Map<Long, Node> shortestPathTopo = new HashMap<Long, Node>();
+    public Topology newDatabaseTopology() {
+	Topology topology = new Topology();
+	topology.readFromDatabase(dbHandler);
 
-	//
-	// Fetch the relevant info from the Switch and Port vertices
-	// from the Titan Graph.
-	//
-	Iterable<ISwitchObject> nodes = op.getActiveSwitches();
-	for (ISwitchObject switchObj : nodes) {
-	    Vertex nodeVertex = switchObj.asVertex();
-	    //
-	    // The Switch info
-	    //
-	    String nodeDpid = nodeVertex.getProperty("dpid").toString();
-	    long nodeId = HexString.toLong(nodeDpid);
-	    Node me = shortestPathTopo.get(nodeId);
-	    if (me == null) {
-		me = new Node(nodeId);
-		shortestPathTopo.put(nodeId, me);
-	    }
-
-	    //
-	    // The local Port info
-	    //
-	    for (Vertex myPortVertex : nodeVertex.getVertices(Direction.OUT, "on")) {
-		// Ignore inactive ports
-		if (! myPortVertex.getProperty("state").toString().equals("ACTIVE"))
-		    continue;
-
-		short myPort = 0;
-		Object obj = myPortVertex.getProperty("number");
-		if (obj instanceof Short) {
-		    myPort = (Short)obj;
-		} else if (obj instanceof Integer) {
-		    Integer int_nodeId = (Integer)obj;
-		    myPort = int_nodeId.shortValue();
-		}
-
-		//
-		// The neighbor Port info
-		//
-		for (Vertex neighborPortVertex : myPortVertex.getVertices(Direction.OUT, "link")) {
-		    // Ignore inactive ports
-		    if (! neighborPortVertex.getProperty("state").toString().equals("ACTIVE"))
-			continue;
-
-		    short neighborPort = 0;
-		    obj = neighborPortVertex.getProperty("number");
-		    if (obj instanceof Short) {
-			neighborPort = (Short)obj;
-		    } else if (obj instanceof Integer) {
-			Integer int_nodeId = (Integer)obj;
-			neighborPort = int_nodeId.shortValue();
-		    }
-		    //
-		    // The neighbor Switch info
-		    //
-		    for (Vertex neighborVertex : neighborPortVertex.getVertices(Direction.IN, "on")) {
-			// Ignore inactive switches
-			String state = neighborVertex.getProperty("state").toString();
-			if (! state.equals(SwitchState.ACTIVE.toString()))
-			    continue;
-
-			String neighborDpid = neighborVertex.getProperty("dpid").toString();
-			long neighborId = HexString.toLong(neighborDpid);
-			Node neighbor = shortestPathTopo.get(neighborId);
-			if (neighbor == null) {
-			    neighbor = new Node(neighborId);
-			    shortestPathTopo.put(neighborId, neighbor);
-			}
-			me.addNeighbor(neighbor, myPort, neighborPort);
-		    }
-		}
-	    }
-	}
-	op.commit();
-
-	return shortestPathTopo;
+	return topology;
     }
 
     /**
-     * Release the state that was populated by
-     * method @ref prepareShortestPathTopo().
+     * Release the topology that was populated by
+     * method @ref newDatabaseTopology().
      *
-     * See the documentation for method @ref prepareShortestPathTopo()
+     * See the documentation for method @ref newDatabaseTopology()
      * for additional information and usage.
      *
-     * @param shortestPathTopo the Shortest Path info handler to release.
+     * @param topology the topology to release.
      */
-    public void dropShortestPathTopo(Map<Long, ?> shortestPathTopo) {
-	shortestPathTopo = null;
+    public void dropTopology(Topology topology) {
+	topology = null;
     }
 
     /**
      * Get the shortest path from a source to a destination by
      * using the pre-populated local topology state prepared
-     * by method @ref prepareShortestPathTopo().
+     * by method @ref newDatabaseTopology().
      *
-     * See the documentation for method @ref prepareShortestPathTopo()
+     * See the documentation for method @ref newDatabaseTopology()
      * for additional information and usage.
      *
-     * @param shortestPathTopoHandler the Shortest Path info handler
-     * to use.
+     * @param topology the topology 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.
      */
-    public DataPath getTopoShortestPath(Map<Long, ?> shortestPathTopoHandler,
-					SwitchPort src, SwitchPort dest) {
-	@SuppressWarnings("unchecked")
-	Map<Long, Node> shortestPathTopo = (Map<Long, Node>)shortestPathTopoHandler;
-	DataPath result_data_path = new DataPath();
-
-	// Initialize the source and destination in the data path to return
-	result_data_path.setSrcPort(src);
-	result_data_path.setDstPort(dest);
-
-	String dpid_src = src.dpid().toString();
-	String dpid_dest = dest.dpid().toString();
-
-	// Get the source vertex
-	Node v_src = shortestPathTopo.get(src.dpid().value());
-	if (v_src == null) {
-	    return null;		// Source vertex not found
-	}
-
-	// Get the destination vertex
-	Node v_dest = shortestPathTopo.get(dest.dpid().value());
-	if (v_dest == null) {
-	    return null;		// Destination vertex not found
-	}
-
-	//
-	// Test whether we are computing a path from/to the same DPID.
-	// If "yes", then just add a single flow entry in the return result.
-	//
-	if (dpid_src.equals(dpid_dest)) {
-	    FlowEntry flowEntry = new FlowEntry();
-	    flowEntry.setDpid(src.dpid());
-	    flowEntry.setInPort(src.port());
-	    flowEntry.setOutPort(dest.port());
-	    result_data_path.flowEntries().add(flowEntry);
-	    return result_data_path;
-	}
-
-	//
-	// Implement the Shortest Path computation by using Breath First Search
-	//
-	Set<Node> visitedSet = new HashSet<Node>();
-	Queue<Node> processingList = new LinkedList<Node>();
-	Map<Node, Node.Link> previousVertexMap = new HashMap<Node, Node.Link>();
-	processingList.add(v_src);
-	visitedSet.add(v_src);
-	Boolean path_found = false;
-	while (! processingList.isEmpty()) {
-	    Node nextVertex = processingList.poll();
-	    if (v_dest == nextVertex) {
-		path_found = true;
-		break;
-	    }
-	    for (Node.Link link : nextVertex.links.values()) {
-		Node child = link.neighbor;
-		if (! visitedSet.contains(child)) {
-		    previousVertexMap.put(child, link);
-		    visitedSet.add(child);
-		    processingList.add(child);
-		}
-	    }
-	}
-	if (! path_found)
-	    return null;		// No path found
-
-	// Collect the path as a list of links
-	List<Node.Link> resultPath = new LinkedList<Node.Link>();
-	Node previousVertex = v_dest;
-	while (! v_src.equals(previousVertex)) {
-	    Node.Link currentLink = previousVertexMap.get(previousVertex);
-	    resultPath.add(currentLink);
-	    previousVertex = currentLink.me;
-	}
-	Collections.reverse(resultPath);
-
-	//
-	// Loop through the result and prepare the return result
-	// as a list of Flow Entries.
-	//
-	Port inPort = new Port(src.port().value());
-	Port outPort;
-	for (Node.Link link: resultPath) {
-	    // Setup the outgoing port, and add the Flow Entry
-	    outPort = new Port(link.myPort);
-
-	    FlowEntry flowEntry = new FlowEntry();
-	    flowEntry.setDpid(new Dpid(link.me.nodeId));
-	    flowEntry.setInPort(inPort);
-	    flowEntry.setOutPort(outPort);
-	    result_data_path.flowEntries().add(flowEntry);
-
-	    // Setup the next incoming port
-	    inPort = new Port(link.neighborPort);
-	}
-	if (resultPath.size() > 0) {
-	    // Add the last Flow Entry
-	    FlowEntry flowEntry = new FlowEntry();
-	    flowEntry.setDpid(new Dpid(dest.dpid().value()));
-	    flowEntry.setInPort(inPort);
-	    flowEntry.setOutPort(dest.port());
-	    result_data_path.flowEntries().add(flowEntry);
-	}
-
-	if (result_data_path.flowEntries().size() > 0)
-	    return result_data_path;
-
-	return null;
+    public DataPath getTopologyShortestPath(Topology topology,
+					    SwitchPort src, SwitchPort dest) {
+	return ShortestPath.getTopologyShortestPath(topology, src, dest);
     }
 
     /**
-     * Get the shortest path from a source to a destination.
+     * Get the shortest path from a source to a destination by using
+     * the underlying database.
      *
      * @param src the source in the shortest path computation.
      * @param dest the destination in the shortest path computation.
@@ -483,167 +246,8 @@
      * found, otherwise null.
      */
     @Override
-    public DataPath getShortestPath(SwitchPort src, SwitchPort dest) {
-	DataPath result_data_path = new DataPath();
-
-	// Initialize the source and destination in the data path to return
-	result_data_path.setSrcPort(src);
-	result_data_path.setDstPort(dest);
-
-	String dpid_src = src.dpid().toString();
-	String dpid_dest = dest.dpid().toString();
-
-	// Get the source and destination switches
-	ISwitchObject srcSwitch =
-	    op.searchActiveSwitch(dpid_src);
-	ISwitchObject destSwitch =
-	    op.searchActiveSwitch(dpid_dest);
-	if (srcSwitch == null || destSwitch == null) {
-	    return null;
-	}
-
-	//
-	// Test whether we are computing a path from/to the same DPID.
-	// If "yes", then just add a single flow entry in the return result.
-	//
-	if (dpid_src.equals(dpid_dest)) {
-	    FlowEntry flowEntry = new FlowEntry();
-	    flowEntry.setDpid(src.dpid());
-	    flowEntry.setInPort(src.port());
-	    flowEntry.setOutPort(dest.port());
-	    result_data_path.flowEntries().add(flowEntry);
-	    op.commit();
-	    return result_data_path;
-	}
-
-	Vertex v_src = srcSwitch.asVertex();	
-	Vertex v_dest = destSwitch.asVertex();
-
-	//
-	// Implement the Shortest Path computation by using Breath First Search
-	//
-	Set<Vertex> visitedSet = new HashSet<Vertex>();
-	Queue<Vertex> processingList = new LinkedList<Vertex>();
-	Map<Vertex, Vertex> previousVertexMap = new HashMap<Vertex, Vertex>();
-
-	processingList.add(v_src);
-	visitedSet.add(v_src);
-	Boolean path_found = false;
-	while (! processingList.isEmpty()) {
-	    Vertex nextVertex = processingList.poll();
-	    if (v_dest.equals(nextVertex)) {
-		path_found = true;
-		break;
-	    }
-	    for (Vertex parentPort : nextVertex.getVertices(Direction.OUT, "on")) {
-		// Ignore inactive ports
-		if (! parentPort.getProperty("state").toString().equals("ACTIVE"))
-			continue;
-
-		for (Vertex childPort : parentPort.getVertices(Direction.OUT, "link")) {
-		    // Ignore inactive ports
-		    if (! childPort.getProperty("state").toString().equals("ACTIVE"))
-			continue;
-
-		    for (Vertex child : childPort.getVertices(Direction.IN, "on")) {
-			// Ignore inactive switches
-			String state = child.getProperty("state").toString();
-			if (! state.equals(SwitchState.ACTIVE.toString()))
-			    continue;
-
-			if (! visitedSet.contains(child)) {
-			    previousVertexMap.put(parentPort, nextVertex);
-			    previousVertexMap.put(childPort, parentPort);
-			    previousVertexMap.put(child, childPort);
-			    visitedSet.add(child);
-			    processingList.add(child);
-			}
-		    }
-		}
-	    }
-	}
-	if (! path_found)
-	    return null;		// No path found
-
-	List<Vertex> resultPath = new LinkedList<Vertex>();
-	Vertex previousVertex = v_dest;
-	resultPath.add(v_dest);
-	while (! v_src.equals(previousVertex)) {
-	    Vertex currentVertex = previousVertexMap.get(previousVertex);
-	    resultPath.add(currentVertex);
-	    previousVertex = currentVertex;
-	}
-	Collections.reverse(resultPath);
-
-
-	//
-	// Loop through the result and prepare the return result
-	// as a list of Flow Entries.
-	//
-	long nodeId = 0;
-	short portId = 0;
-	Port inPort = new Port(src.port().value());
-	Port outPort = new Port();
-	int idx = 0;
-	for (Vertex v: resultPath) {
-	    String type = v.getProperty("type").toString();
-	    // System.out.println("type: " + type);
-	    if (type.equals("port")) {
-		//String number = v.getProperty("number").toString();
-		// System.out.println("number: " + number);
-
-		Object obj = v.getProperty("number");
-		// String class_str = obj.getClass().toString();
-		if (obj instanceof Short) {
-		    portId = (Short)obj;
-		} else if (obj instanceof Integer) {
-		    Integer int_nodeId = (Integer)obj;
-		    portId = int_nodeId.shortValue();
-		    // int int_nodeId = (Integer)obj;
-		    // portId = (short)int_nodeId.;
-		}
-	    } else if (type.equals("switch")) {
-		String dpid = v.getProperty("dpid").toString();
-		nodeId = HexString.toLong(dpid);
-
-		// System.out.println("dpid: " + dpid);
-	    }
-	    idx++;
-	    if (idx == 1) {
-		continue;
-	    }
-	    int mod = idx % 3;
-	    if (mod == 0) {
-		// Setup the incoming port
-		inPort = new Port(portId);
-		continue;
-	    }
-	    if (mod == 2) {
-		// Setup the outgoing port, and add the Flow Entry
-		outPort = new Port(portId);
-
-		FlowEntry flowEntry = new FlowEntry();
-		flowEntry.setDpid(new Dpid(nodeId));
-		flowEntry.setInPort(inPort);
-		flowEntry.setOutPort(outPort);
-		result_data_path.flowEntries().add(flowEntry);
-		continue;
-	    }
-	}
-	if (idx > 0) {
-	    // Add the last Flow Entry
-	    FlowEntry flowEntry = new FlowEntry();
-	    flowEntry.setDpid(new Dpid(nodeId));
-	    flowEntry.setInPort(inPort);
-	    flowEntry.setOutPort(dest.port());
-	    result_data_path.flowEntries().add(flowEntry);
-	}
-
-	op.commit();
-	if (result_data_path.flowEntries().size() > 0)
-	    return result_data_path;
-
-	return null;
+    public DataPath getDatabaseShortestPath(SwitchPort src, SwitchPort dest) {
+	return ShortestPath.getDatabaseShortestPath(dbHandler, src, dest);
     }
 
     /**
@@ -655,7 +259,7 @@
      */
     @Override
     public Boolean routeExists(SwitchPort src, SwitchPort dest) {
-	DataPath dataPath = getShortestPath(src, dest);
+	DataPath dataPath = getDatabaseShortestPath(src, dest);
 	return (dataPath != null);
     }
 }
diff --git a/src/main/java/net/onrc/onos/ofcontroller/topology/web/RouteResource.java b/src/main/java/net/onrc/onos/ofcontroller/topology/web/RouteResource.java
index a730719..1cb39b3 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/topology/web/RouteResource.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/topology/web/RouteResource.java
@@ -37,8 +37,9 @@
 	Port dstPort = new Port(Short.parseShort(dstPortStr));
         
 	DataPath result =
-	    topologyNetService.getShortestPath(new SwitchPort(srcDpid, srcPort),
-					       new SwitchPort(dstDpid, dstPort));
+	    topologyNetService.getDatabaseShortestPath(
+		new SwitchPort(srcDpid, srcPort),
+		new SwitchPort(dstDpid, dstPort));
 	if (result != null) {
 	    return result;
 	} else {