diff --git a/README.md b/README.md
index ea1553a..bfd8d57 100644
--- a/README.md
+++ b/README.md
@@ -17,11 +17,18 @@
 
     $ mvn clean
     $ mvn compile
-     
+
+
+Dependencies
+------------
+1. Zookeeper
+    Download and install apache-zookeeper-3.4.5: http://zookeeper.apache.org/releases.html
+2. Cassandra
+    Download and install apache-cassandra-1.2.2: http://cassandra.apache.org/download/
+
 Running ONOS
 ------------
 
-
 1. Start zookeeper
 
     $ cd (ZOOKEEPER-INSTALL-DIR)/bin
@@ -38,8 +45,30 @@
 
 3. Start ONOS instance
 
+    $ cd (ONOS-INSTALL-DIR)/
+
     $ ./start-onos.sh start
     
 4. Start ONOS rest apis
 
     $ ./start-rest.sh start
+
+Running ONOS with Cassandra embedded (Optional)
+-----------------------------------------------
+
+1. Start Zookeeper
+
+    $ cd (ZOOKEEPER-INSTALL-DIR)/bin
+    
+    $ ./zkServer.sh start
+    
+2. Start ONOS and Cassandra embedded
+
+    $ cd (ONOS-INSTAL_DIR)/
+    
+    $ ./start-onos-embedded.sh start
+    
+3. Start ONOS rest apis
+
+    $ ./start-rest.sh start
+
diff --git a/src/main/java/net/onrc/onos/ofcontroller/core/internal/LinkStorageImpl.java b/src/main/java/net/onrc/onos/ofcontroller/core/internal/LinkStorageImpl.java
index c89b2fa..b33591e 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/core/internal/LinkStorageImpl.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/core/internal/LinkStorageImpl.java
@@ -27,11 +27,21 @@
 	protected static Logger log = LoggerFactory.getLogger(LinkStorageImpl.class);
 	protected GraphDBOperation dbop;
 
+	/**
+	 * Update a record in the LinkStorage in a way provided by op.
+	 * @param link Record of a link to be updated.
+	 * @param op Operation to be done.
+	 */
 	@Override
 	public void update(Link link, DM_OPERATION op) {
 		update(link, (LinkInfo)null, op);
 	}
 
+	/**
+	 * Update multiple records in the LinkStorage in a way provided by op.
+	 * @param links List of records to be updated.
+	 * @param op Operation to be done.
+	 */
 	@Override
 	public void update(List<Link> links, DM_OPERATION op) {
 		for (Link lt: links) {
@@ -39,6 +49,12 @@
 		}
 	}
 
+	/**
+	 * Update a record of link with meta-information in the LinkStorage in a way provided by op.
+	 * @param link Record of a link to update.
+	 * @param linkinfo Meta-information of a link to be updated.
+	 * @param op Operation to be done.
+	 */
 	@Override
 	public void update(Link link, LinkInfo linkinfo, DM_OPERATION op) {
 		switch (op) {
@@ -53,6 +69,12 @@
 		}
 	}
 	
+	/**
+	 * Perform INSERT/CREATE/UPDATE operation to update the LinkStorage.
+	 * @param lt Record of a link to be updated.
+	 * @param linkinfo Meta-information of a link to be updated.
+	 * @param op Operation to be done. (only INSERT/CREATE/UPDATE is acceptable)
+	 */
 	public void updateLink(Link lt, LinkInfo linkinfo, DM_OPERATION op) {
 		IPortObject vportSrc = null, vportDst = null;
 	
@@ -70,7 +92,6 @@
             vportDst = dbop.searchPort(dpid, port);
                         
             if (vportSrc != null && vportDst != null) {
-         	       	
             	// check if the link exists
             	
             	Iterable<IPortObject> currPorts = vportSrc.getLinkedPorts();
@@ -78,7 +99,7 @@
             	for (IPortObject V : currPorts) {
             		currLinks.add(V);
             	}
-            	
+
             	if (currLinks.contains(vportDst)) {
             		// TODO: update linkinfo
             		if (op.equals(DM_OPERATION.INSERT) || op.equals(DM_OPERATION.CREATE)) {
@@ -104,6 +125,10 @@
         }
 	}
 	
+	/**
+	 * Delete multiple records in the LinkStorage.
+	 * @param links List of records to be deleted.
+	 */
 	@Override
 	public void deleteLinks(List<Link> links) {
 
@@ -112,7 +137,10 @@
 		}
 	}
 	
-
+	/**
+	 * Delete a record in the LinkStorage.
+	 * @param link Record to be deleted.
+	 */
 	@Override
 	public void deleteLink(Link lt) {
 		IPortObject vportSrc = null, vportDst = null;
@@ -162,59 +190,114 @@
         }
 	}
 
+	/**
+	 * Get list of all links connected to the port specified by given DPID and port number.
+	 * @param dpid DPID of desired port.
+	 * @param port Port number of desired port.
+	 * @return List of links. Empty list if no port was found.
+	 */
 	// TODO: Fix me
 	@Override
 	public List<Link> getLinks(Long dpid, short port) {
-		IPortObject vportSrc;
+    	List<Link> links = new ArrayList<Link>();
     	
-		vportSrc = dbop.searchPort(HexString.toHexString(dpid), port);
-		if (vportSrc != null) {
-			
-     		for (Edge e : vportSrc.asVertex().getEdges(Direction.OUT)) {
-     			if (e.getLabel().equals("link")) {
-     				break;
-     			}
-     		}
-		}
-     	return null;
+    	IPortObject srcPort = dbop.searchPort(HexString.toHexString(dpid), port);
+    	ISwitchObject srcSw = srcPort.getSwitch();
+    	
+    	if(srcSw != null) {
+        	for(IPortObject dstPort : srcPort.getLinkedPorts()) {
+        		ISwitchObject dstSw = dstPort.getSwitch();
+        		Link link = new Link(HexString.toLong(srcSw.getDPID()),
+        				srcPort.getNumber(),
+        				HexString.toLong(dstSw.getDPID()),
+        				dstPort.getNumber());
+    		
+        		links.add(link);
+        	}
+    	}
+    	
+     	return links;
 	}
 	
+	/**
+	 * Initialize the object. Open LinkStorage using given configuration file.
+	 * @param conf Path (absolute path for now) to configuration file.
+	 */
 	@Override
 	public void init(String conf) {
 		//TODO extract the DB location from properties
 		this.dbop = new GraphDBOperation(conf);
 	}
 
+	/**
+	 * Delete records of the links connected to the port specified by given DPID and port number.
+	 * @param dpid DPID of desired port.
+	 * @param port Port number of desired port.
+	 */
+	// TODO: Fix me
 	@Override
 	public void deleteLinksOnPort(Long dpid, short port) {
-		// TODO Auto-generated method stub
+		List<Link> linksToDelete = getLinks(dpid,port);
 		
+		for(Link l : linksToDelete) {
+			deleteLink(l);
+		}
 	}
 
+	/**
+	 * Get list of all links connected to the switch specified by given DPID.
+	 * @param dpid DPID of desired switch.
+	 * @return List of links. Empty list if no port was found.
+	 */
+	// TODO: Fix me
 	@Override
 	public List<Link> getLinks(String dpid) {
-		// TODO Auto-generated method stub
-		return null;
+		List<Link> links = new ArrayList<Link>();
+
+		ISwitchObject srcSw = dbop.searchSwitch(dpid);
+		
+		if(srcSw != null) {
+			for(IPortObject srcPort : srcSw.getPorts()) {
+				for(IPortObject dstPort : srcPort.getLinkedPorts()) {
+					ISwitchObject dstSw = dstPort.getSwitch();
+					if(dstSw != null) {
+		        		Link link = new Link(HexString.toLong(srcSw.getDPID()),
+		        				srcPort.getNumber(),
+		        				HexString.toLong(dstSw.getDPID()),
+		        				dstPort.getNumber());
+		        		links.add(link);
+					}
+				}
+			}
+		}
+		
+		return links;
 	}
 
+	/**
+	 * Get list of all links whose state is ACTIVE.
+	 * @return List of active links. Empty list if no port was found.
+	 */
 	public List<Link> getActiveLinks() {
 		Iterable<ISwitchObject> switches = dbop.getActiveSwitches();
 
 		List<Link> links = new ArrayList<Link>(); 
-		for (ISwitchObject sw : switches) {
-			GremlinPipeline<Vertex, Link> pipe = new GremlinPipeline<Vertex, Link>();
-			ExtractLink extractor = new ExtractLink();
-
-			pipe.start(sw.asVertex());
-			pipe.enablePath(true);
-			pipe.out("on").out("link").in("on").path().step(extractor);
+		
+		for (ISwitchObject srcSw : switches) {
+			for(IPortObject srcPort : srcSw.getPorts()) {
+				for(IPortObject dstPort : srcPort.getLinkedPorts()) {
+					ISwitchObject dstSw = dstPort.getSwitch();
 					
-			while (pipe.hasNext() ) {
-				Link l = pipe.next();
-				links.add(l);
+					if(dstSw != null && dstSw.getState().equals("ACTIVE")) {
+						links.add(new Link(HexString.toLong(srcSw.getDPID()),
+								srcPort.getNumber(),
+								HexString.toLong(dstSw.getDPID()),
+								dstPort.getNumber()));
+					}
+				}
 			}
-						
 		}
+		
 		return links;
 	}
 	
@@ -244,10 +327,16 @@
 		}
 	}
 	
+	/**
+	 * Finalize the object.
+	 */
 	public void finalize() {
 		close();
 	}
 
+	/**
+	 * Close LinkStorage.
+	 */
 	@Override
 	public void close() {
 		// TODO Auto-generated method stub
diff --git a/src/test/java/net/floodlightcontroller/core/internal/TestDatabaseManager.java b/src/test/java/net/floodlightcontroller/core/internal/TestDatabaseManager.java
new file mode 100644
index 0000000..8a09139
--- /dev/null
+++ b/src/test/java/net/floodlightcontroller/core/internal/TestDatabaseManager.java
@@ -0,0 +1,76 @@
+package net.floodlightcontroller.core.internal;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Iterator;
+import java.util.Set;
+
+import junit.framework.Assert;
+
+import org.apache.commons.io.FileUtils;
+
+import com.thinkaurelius.titan.core.TitanFactory;
+import com.thinkaurelius.titan.core.TitanGraph;
+import com.tinkerpop.blueprints.TransactionalGraph.Conclusion;
+import com.tinkerpop.blueprints.Vertex;
+import com.tinkerpop.blueprints.util.io.graphml.GraphMLReader;
+
+public class TestDatabaseManager {
+	private static final String testDbLocation = "/tmp/onos-testdb";
+	
+	//private static final String testDbGraphML = "<?xml version=\"1.0\" ?><graphml xmlns=\"http://graphml.graphdrawing.org/xmlns\">    <key id=\"id\" for=\"node\" attr.name=\"id\" attr.type=\"string\"></key>    <key id=\"type\" for=\"node\" attr.name=\"type\" attr.type=\"string\"></key>    <key id=\"dpid\" for=\"node\" attr.name=\"dpid\" attr.type=\"string\"></key>    <key id=\"desc\" for=\"node\" attr.name=\"desc\" attr.type=\"string\"></key>    <key id=\"number\" for=\"node\" attr.name=\"number\" attr.type=\"int\"></key>    <key id=\"dl_addr\" for=\"node\" attr.name=\"dl_addr\" attr.type=\"string\"></key>    <key id=\"nw_addr\" for=\"node\" attr.name=\"nw_addr\" attr.type=\"string\"></key>    <key id=\"id\" for=\"edge\" attr.name=\"id\" attr.type=\"string\"></key>    <key id=\"source\" for=\"edge\" attr.name=\"source\" attr.type=\"string\"></key>    <key id=\"target\" for=\"edge\" attr.name=\"target\" attr.type=\"string\"></key>    <key id=\"label\" for=\"edge\" attr.name=\"label\" attr.type=\"string\"></key>    <graph id=\"G\" edgedefault=\"directed\">        <node id=\"1\">            <data key=\"type\">switch</data>            <data key=\"dpid\">00:00:00:00:00:00:0a:01</data>            <data key=\"desc\">OpenFlow Switch at SEA</data>        </node>        <node id=\"2\">            <data key=\"type\">switch</data>            <data key=\"dpid\">00:00:00:00:00:00:0a:02</data>            <data key=\"desc\">OpenFlow Switch at LAX</data>        </node>        <node id=\"3\">            <data key=\"type\">switch</data>            <data key=\"dpid\">00:00:00:00:00:00:0a:03</data>            <data key=\"desc\">OpenFlow Switch at CHI</data>        </node>        <node id=\"4\">            <data key=\"type\">switch</data>            <data key=\"dpid\">00:00:00:00:00:00:0a:04</data>            <data key=\"desc\">OpenFlow Switch at IAH</data>        </node>        <node id=\"5\">            <data key=\"type\">switch</data>            <data key=\"dpid\">00:00:00:00:00:00:0a:05</data>            <data key=\"desc\">OpenFlow Switch at NYC</data>        </node>        <node id=\"6\">            <data key=\"type\">switch</data>            <data key=\"dpid\">00:00:00:00:00:00:0a:06</data>            <data key=\"desc\">OpenFlow Switch at ATL</data>        </node>        <node id=\"100\">            <data key=\"type\">port</data>            <data key=\"number\">1</data>            <data key=\"desc\">port 1 at SEA Switch</data>        </node>        <node id=\"101\">            <data key=\"type\">port</data>            <data key=\"number\">2</data>            <data key=\"desc\">port 2 at SEA Switch</data>        </node>        <node id=\"102\">            <data key=\"type\">port</data>            <data key=\"number\">3</data>            <data key=\"desc\">port 3 at SEA Switch</data>        </node>        <node id=\"103\">            <data key=\"type\">port</data>            <data key=\"number\">4</data>            <data key=\"desc\">port 4 at SEA Switch</data>        </node>        <node id=\"104\">            <data key=\"type\">port</data>            <data key=\"number\">1</data>            <data key=\"desc\">port 1 at LAX Switch</data>        </node>        <node id=\"105\">            <data key=\"type\">port</data>            <data key=\"number\">2</data>            <data key=\"desc\">port 2 at LAX Switch</data>        </node>        <node id=\"106\">            <data key=\"type\">port</data>            <data key=\"number\">3</data>            <data key=\"desc\">port 3 at LAX Switch</data>        </node>        <node id=\"107\">            <data key=\"type\">port</data>            <data key=\"number\">1</data>            <data key=\"desc\">port 1 at CHI Switch</data>        </node>        <node id=\"108\">            <data key=\"type\">port</data>            <data key=\"number\">2</data>            <data key=\"desc\">port 2 at CHI Switch</data>        </node>        <node id=\"109\">            <data key=\"type\">port</data>            <data key=\"number\">3</data>            <data key=\"desc\">port 3 at CHI Switch</data>        </node>        <node id=\"110\">            <data key=\"type\">port</data>            <data key=\"number\">4</data>            <data key=\"desc\">port 4 at CHI Switch</data>        </node>        <node id=\"111\">            <data key=\"type\">port</data>            <data key=\"number\">1</data>            <data key=\"desc\">port 1 at IAH Switch</data>        </node>        <node id=\"112\">            <data key=\"type\">port</data>            <data key=\"number\">2</data>            <data key=\"desc\">port 2 at IAH Switch</data>        </node>        <node id=\"113\">            <data key=\"type\">port</data>            <data key=\"number\">3</data>            <data key=\"desc\">port 3 at IAH Switch</data>        </node>        <node id=\"114\">            <data key=\"type\">port</data>            <data key=\"number\">1</data>            <data key=\"desc\">port 1 at NYC Switch</data>        </node>        <node id=\"115\">            <data key=\"type\">port</data>            <data key=\"number\">2</data>            <data key=\"desc\">port 2 at NYC Switch</data>        </node>        <node id=\"116\">            <data key=\"type\">port</data>            <data key=\"number\">3</data>            <data key=\"desc\">port 3 at NYC Switch</data>        </node>        <node id=\"117\">            <data key=\"type\">port</data>            <data key=\"number\">1</data>            <data key=\"desc\">port 1 at ATL Switch</data>        </node>        <node id=\"118\">            <data key=\"type\">port</data>            <data key=\"number\">2</data>            <data key=\"desc\">port 2 at ATL Switch</data>        </node>        <node id=\"119\">            <data key=\"type\">port</data>            <data key=\"number\">3</data>            <data key=\"desc\">port 3 at ATL Switch</data>        </node>        <node id=\"1000\">            <data key=\"type\">device</data>            <data key=\"dl_addr\">20:c9:d0:4a:e1:73</data>            <data key=\"nw_addr\">192.168.10.101</data>        </node>        <node id=\"1001\">            <data key=\"type\">device</data>            <data key=\"dl_addr\">20:c9:d0:4a:e1:62</data>            <data key=\"nw_addr\">192.168.20.101</data>        </node>        <node id=\"1002\">            <data key=\"type\">device</data>            <data key=\"dl_addr\">10:40:f3:e6:8d:55</data>            <data key=\"nw_addr\">192.168.10.1</data>        </node>        <node id=\"1003\">            <data key=\"type\">device</data>            <data key=\"dl_addr\">a0:b3:cc:9c:c6:88</data>            <data key=\"nw_addr\">192.168.20.1</data>        </node>        <node id=\"1004\">            <data key=\"type\">device</data>            <data key=\"dl_addr\">00:04:20:e2:50:a2</data>            <data key=\"nw_addr\">192.168.30.1</data>        </node>        <node id=\"1005\">            <data key=\"type\">device</data>            <data key=\"dl_addr\">58:55:ca:c4:1b:a0</data>            <data key=\"nw_addr\">192.168.40.1</data>        </node>        <edge id=\"10000\" source=\"1\" target=\"101\" label=\"on\"></edge>        <edge id=\"10001\" source=\"1\" target=\"102\" label=\"on\"></edge>        <edge id=\"10002\" source=\"1\" target=\"103\" label=\"on\"></edge>        <edge id=\"10003\" source=\"2\" target=\"104\" label=\"on\"></edge>        <edge id=\"10004\" source=\"2\" target=\"105\" label=\"on\"></edge>        <edge id=\"10005\" source=\"2\" target=\"106\" label=\"on\"></edge>        <edge id=\"10006\" source=\"3\" target=\"107\" label=\"on\"></edge>        <edge id=\"10007\" source=\"3\" target=\"108\" label=\"on\"></edge>        <edge id=\"10008\" source=\"3\" target=\"109\" label=\"on\"></edge>        <edge id=\"10009\" source=\"3\" target=\"110\" label=\"on\"></edge>        <edge id=\"10010\" source=\"4\" target=\"111\" label=\"on\"></edge>        <edge id=\"10011\" source=\"4\" target=\"112\" label=\"on\"></edge>        <edge id=\"10012\" source=\"4\" target=\"113\" label=\"on\"></edge>        <edge id=\"10013\" source=\"5\" target=\"114\" label=\"on\"></edge>        <edge id=\"10014\" source=\"5\" target=\"115\" label=\"on\"></edge>        <edge id=\"10015\" source=\"5\" target=\"116\" label=\"on\"></edge>        <edge id=\"10016\" source=\"6\" target=\"117\" label=\"on\"></edge>        <edge id=\"10017\" source=\"6\" target=\"118\" label=\"on\"></edge>        <edge id=\"10018\" source=\"6\" target=\"119\" label=\"on\"></edge>        <edge id=\"11000\" source=\"101\" target=\"107\" label=\"link\"></edge>         <edge id=\"11003\" source=\"105\" target=\"111\" label=\"link\"></edge>        <edge id=\"11004\" source=\"107\" target=\"101\" label=\"link\"></edge>        <edge id=\"11005\" source=\"108\" target=\"112\" label=\"link\"></edge>        <edge id=\"11006\" source=\"109\" target=\"114\" label=\"link\"></edge>        <edge id=\"11007\" source=\"111\" target=\"105\" label=\"link\"></edge>        <edge id=\"11008\" source=\"112\" target=\"108\" label=\"link\"></edge>        <edge id=\"11009\" source=\"113\" target=\"117\" label=\"link\"></edge>        <edge id=\"11010\" source=\"114\" target=\"109\" label=\"link\"></edge>        <edge id=\"11011\" source=\"115\" target=\"118\" label=\"link\"></edge>        <edge id=\"11012\" source=\"117\" target=\"113\" label=\"link\"></edge>        <edge id=\"11013\" source=\"118\" target=\"115\" label=\"link\"></edge>        <edge id=\"12000\" source=\"103\" target=\"1000\" label=\"host\"></edge>        <edge id=\"12001\" source=\"103\" target=\"1001\" label=\"host\"></edge>        <edge id=\"12002\" source=\"110\" target=\"1002\" label=\"host\"></edge>        <edge id=\"12003\" source=\"116\" target=\"1003\" label=\"host\"></edge>        <edge id=\"12004\" source=\"106\" target=\"1004\" label=\"host\"></edge>        <edge id=\"12005\" source=\"119\" target=\"1005\" label=\"host\"></edge>      </graph>    </graphml>";
+	
+	private static final String testDataLocation = "titan/schema/test-network.xml";
+	
+	public static TitanGraph getTestDatabase(){
+		//return TitanFactory.open(testDbLocation);
+//		return TitanFactory.openInMemoryGraph();
+		return TitanFactory.open(testDbLocation);
+	}
+	
+	public static void populateTestData(TitanGraph titanGraph){
+		Set<String> s = titanGraph.getIndexedKeys(Vertex.class);
+        if (!s.contains("dpid")) {
+           titanGraph.createKeyIndex("dpid", Vertex.class);
+           titanGraph.stopTransaction(Conclusion.SUCCESS);
+        }
+        if (!s.contains("type")) {
+        	titanGraph.createKeyIndex("type", Vertex.class);
+        	titanGraph.stopTransaction(Conclusion.SUCCESS);
+        }
+        
+        //InputStream graphMLStream = new ByteArrayInputStream(testDbGraphML.getBytes());
+        
+        try {
+        	InputStream graphMLStream = new FileInputStream(testDataLocation);
+			GraphMLReader.inputGraph(titanGraph, graphMLStream);
+		} catch (FileNotFoundException e) {
+			Assert.fail("Test data file not found: " + testDataLocation);
+		} catch (IOException e) {
+			e.printStackTrace();
+			Assert.fail("IOException thrown");
+		}
+        
+        //Change the type of all port numbers to short in the database
+        Iterator<Vertex> it = titanGraph.getVertices("type", "port").iterator();
+        while (it.hasNext()){
+        	Vertex port = it.next();
+        	Integer portNum = (Integer) port.getProperty("number");
+        	port.setProperty("number", portNum.shortValue());
+        }
+        titanGraph.stopTransaction(Conclusion.SUCCESS);
+	}
+	
+	public static void deleteTestDatabase(){
+		try {
+			FileUtils.deleteDirectory(new File(testDbLocation));
+		} catch (IOException e) {
+			System.out.println("delete failed");
+			e.printStackTrace();
+		}
+	}
+	
+}
\ No newline at end of file
diff --git a/src/test/java/net/onrc/onos/ofcontroller/core/internal/LinkStorageImplTest.java b/src/test/java/net/onrc/onos/ofcontroller/core/internal/LinkStorageImplTest.java
index b03af4e..7bf2b1a 100644
--- a/src/test/java/net/onrc/onos/ofcontroller/core/internal/LinkStorageImplTest.java
+++ b/src/test/java/net/onrc/onos/ofcontroller/core/internal/LinkStorageImplTest.java
@@ -4,125 +4,533 @@
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
-import java.util.Iterator;
+import java.util.ArrayList;
 import java.util.List;
 
 import net.floodlightcontroller.routing.Link;
 import net.onrc.onos.ofcontroller.core.ILinkStorage;
 import net.onrc.onos.ofcontroller.core.INetMapStorage.DM_OPERATION;
+import net.onrc.onos.ofcontroller.core.internal.TestableGraphDBOperation.TestPortObject;
+import net.onrc.onos.util.GraphDBConnection;
+import net.onrc.onos.util.GraphDBOperation;
+import net.onrc.onos.ofcontroller.linkdiscovery.LinkInfo;
 
+import org.easymock.EasyMock;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Ignore;
 import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.openflow.protocol.OFPhysicalPort;
+import org.openflow.util.HexString;
+import org.powermock.api.easymock.PowerMock;
+import org.powermock.core.classloader.annotations.PrepareForTest;
+import org.powermock.modules.junit4.PowerMockRunner;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
-import com.thinkaurelius.titan.core.TitanGraph;
-import com.tinkerpop.blueprints.Vertex;
-import com.tinkerpop.gremlin.java.GremlinPipeline;
-
+@RunWith(PowerMockRunner.class)
+@PrepareForTest({LinkStorageImpl.class, GraphDBConnection.class, GraphDBOperation.class})
 public class LinkStorageImplTest {
+	protected static Logger log = LoggerFactory.getLogger(LinkStorageImplTest.class);
+
 	private static ILinkStorage linkStorage;
-	private static TitanGraph titanGraph;
 	
-	//TODO Future ideas:
-	//Test add links with CREATE and UPDATE
-	//Test adding existing link again
+	// Mock GraphDBConnection (do nothing)
+	private static GraphDBConnection conn;
 	
+	// Mock GraphDBOperation (mocks port-related methods only)
+	private static TestableGraphDBOperation ope;
+
+	/**
+	 * Setup code called before each tests.
+	 * Read test graph data and replace DB access by test graph data.
+	 * @throws Exception
+	 */
 	@Before
 	public void setUp() throws Exception{
-		titanGraph = TestDatabaseManager.getTestDatabase();
-		TestDatabaseManager.populateTestData(titanGraph);
+		PowerMock.mockStatic(GraphDBConnection.class);
+		PowerMock.suppress(PowerMock.constructor(GraphDBConnection.class));
+		conn = PowerMock.createNiceMock(GraphDBConnection.class);
+		EasyMock.expect(GraphDBConnection.getInstance((String)EasyMock.anyObject())).andReturn(conn).anyTimes();
+		PowerMock.replay(GraphDBConnection.class);
 		
-		linkStorage = new TestableLinkStorageImpl(titanGraph);
+		ope = new TestableGraphDBOperation();
+		PowerMock.expectNew(GraphDBOperation.class, (GraphDBConnection)EasyMock.anyObject()).andReturn(ope).anyTimes();
+		PowerMock.replay(GraphDBOperation.class);
+
+		linkStorage = new LinkStorageImpl();
+		linkStorage.init("/dummy/path/to/conf");
+		
+		initLinks();
 	}
 	
+	/**
+	 * Closing code called after each tests.
+	 * Discard test graph data.
+	 * @throws Exception
+	 */
 	@After
-	public void tearDown() throws Exception {		
-		titanGraph.shutdown();
+	public void tearDown() throws Exception {
+		// finish code
+		linkStorage.close();
+		ope.close();
 	}
 	
-	/*
-	 * Add a link between port 1.102 and 2.104
-	 * i.e SEA switch port 3 to LAX switch port 1
+	// TODO: remove @Ignore after UPDATE method is implemented
+	/**
+	 * Test if update() can correctly updates LinkInfo for a Link.
+	 */
+	@Ignore @Test
+	public void testUpdate_UpdateSingleLink() {
+		Link linkToUpdate= createExistingLink();
+		long currentTime = System.currentTimeMillis();
+		LinkInfo infoToUpdate = createFeasibleLinkInfo(currentTime);
+		LinkInfo infoToVerify = createFeasibleLinkInfo(currentTime);
+
+		linkStorage.update(linkToUpdate, infoToUpdate, ILinkStorage.DM_OPERATION.UPDATE);
+		
+		doTestLinkHasStateOf(linkToUpdate, infoToVerify);
+	}
+	
+	/**
+	 * Test if update() can correctly creates a Link.
 	 */
 	@Test
-	public void testAddSingleLink(){
-		Link linkToAdd = new Link(Long.decode("0x0000000000000a01"), 3, Long.decode("0x0000000000000a02"), 1);
+	public void testUpdate_CreateSingleLink() {
+		Link linkToCreate = createFeasibleLink();
+		Link linkToVerify = createFeasibleLink();
 		
 		//Use the link storage API to add the link
-		linkStorage.update(linkToAdd, ILinkStorage.DM_OPERATION.INSERT);
+		linkStorage.update(linkToCreate, ILinkStorage.DM_OPERATION.CREATE);
+		doTestLinkExist(linkToVerify);
+	}
+
+	/**
+	 * Test if update() can correctly inserts a Link.
+	 */
+	@Test
+	public void testUpdate_InsertSingleLink(){
+		Link linkToInsert = createFeasibleLink();
+		Link linkToVerify = createFeasibleLink();
 		
-		//Test if it was added correctly with the Gremlin API
-		GremlinPipeline<Vertex, Vertex> pipe = new GremlinPipeline<Vertex, Vertex>();
-		Iterator<Vertex> it = titanGraph.getVertices("dpid", "00:00:00:00:00:00:0a:01").iterator();
-		
-		assertTrue(it.hasNext());
-		Vertex sw1 = it.next();
-		assertFalse(it.hasNext());
-		
-		pipe.start(sw1).out("on").has("number", (short)3).out("link").in("on");
-		
-		assertTrue(pipe.hasNext());
-		Vertex sw2 = pipe.next();
-		assertFalse(pipe.hasNext());
-		
-		//Check we ended up at the right vertex
-		assertEquals((String)sw2.getProperty("dpid"), "00:00:00:00:00:00:0a:02");
+		//Use the link storage API to add the link
+		linkStorage.update(linkToInsert, ILinkStorage.DM_OPERATION.INSERT);
+		doTestLinkExist(linkToVerify);
 	}
 	
-	//TODO enable once method is written
+	/**
+	 * Test if update() can correctly deletes a Link.
+	 */
+	@Test
+	public void testUpdate_DeleteSingleLink(){
+		Link linkToDelete = createExistingLink();
+		Link linkToVerify = createExistingLink();
+
+		// Test deletion of existing link
+		linkStorage.update(linkToDelete, DM_OPERATION.DELETE);
+		doTestLinkNotExist(linkToVerify);
+	}
+
+	/**
+	 * Test if update() can correctly creates multiple Links.
+	 */
+	@Test
+	public void testUpdate_CreateLinks(){
+		List<Link> linksToCreate = createFeasibleLinks();
+		List<Link> linksToVerify = createFeasibleLinks();
+
+		// Test creation of new links
+		linkStorage.update(linksToCreate, ILinkStorage.DM_OPERATION.CREATE);
+		for(Link l : linksToVerify) {
+			doTestLinkExist(l);
+		}
+	}
+	
+	/**
+	 * Test if update() can handle mixture of normal/abnormal input for creation of Links.
+	 * Deprecated: DBOperation is responsible.
+	 */
 	@Ignore @Test
-	public void testGetLinks(){
-		//TODO Make sure this works when the implementation is written
-		List<Link> list = linkStorage.getLinks(Long.decode("0x0000000000000a01"), (short)2);
+	public void testUpdate_CreateLinks_Mixuture(){
+		List<Link> linksToCreate = new ArrayList<Link>();
+		linksToCreate.add(createFeasibleLink());
+		linksToCreate.add(createExistingLink());
+		
+		// Test creation of mixture of new/existing links
+		linkStorage.update(linksToCreate, ILinkStorage.DM_OPERATION.CREATE);
+		doTestLinkExist(createFeasibleLink());
+		doTestLinkExist(createExistingLink());
+	}
+
+	/**
+	 * Test if update() can correctly inserts multiple Links.
+	 */
+	@Test
+	public void testUpdate_InsertLinks(){
+		List<Link> linksToInsert = createFeasibleLinks();
+		List<Link> linksToVerify = createFeasibleLinks();
+		
+		// Test insertion of new links
+		linkStorage.update(linksToInsert, ILinkStorage.DM_OPERATION.INSERT);
+		for(Link l : linksToVerify) {
+			doTestLinkExist(l);
+		}
+	}
+	
+	/**
+	 * Test if update() can handle mixture of normal/abnormal input for creation of Links.
+	 */
+	@Ignore @Test
+	public void testUpdate_InsertLinks_Mixuture(){
+		List<Link> linksToInsert = new ArrayList<Link>();
+		linksToInsert.add(createFeasibleLink());
+		linksToInsert.add(createExistingLink());
+		
+		// Test insertion of mixture of new/existing links
+		linkStorage.update(linksToInsert, ILinkStorage.DM_OPERATION.INSERT);
+		doTestLinkExist(createFeasibleLink());
+		doTestLinkExist(createExistingLink());
+	}
+
+	/**
+	 * Test if update() can correctly deletes multiple Links.
+	 */
+	@Test
+	public void testUpdate_DeleteLinks(){
+		List<Link> linksToDelete = createExistingLinks();
+		List<Link> linksToVerify = createExistingLinks();
+		
+		// Test deletion of existing links
+		linkStorage.update(linksToDelete, ILinkStorage.DM_OPERATION.DELETE);
+		for(Link l : linksToVerify) {
+			doTestLinkNotExist(l);
+		}
+	}
+	
+	/**
+	 * Test if update() can handle mixture of normal/abnormal input for deletion of Links.
+	 */
+	@Ignore @Test
+	public void testUpdate_DeleteLinks_Mixuture(){
+		List<Link> linksToDelete = new ArrayList<Link>();
+		linksToDelete.add(createFeasibleLink());
+		linksToDelete.add(createExistingLink());
+		
+		// Test deletion of mixture of new/existing links
+		linkStorage.update(linksToDelete, ILinkStorage.DM_OPERATION.DELETE);
+		doTestLinkNotExist(createFeasibleLink());
+		doTestLinkNotExist(createExistingLink());
+	}
+	
+	// TODO: remove @Ignore after UPDATE method is implemented
+	/**
+	 * Test if updateLink() can correctly updates LinkInfo for a Link.
+	 */
+	@Ignore @Test
+	public void testUpdateLink_Update() {
+		Link linkToUpdate= createExistingLink();
+		long currentTime = System.currentTimeMillis();
+		LinkInfo infoToUpdate = createFeasibleLinkInfo(currentTime);
+		LinkInfo infoToVerify = createFeasibleLinkInfo(currentTime);
+
+		linkStorage.updateLink(linkToUpdate, infoToUpdate, ILinkStorage.DM_OPERATION.UPDATE);
+		
+		doTestLinkHasStateOf(linkToUpdate, infoToVerify);
+	}
+	
+	/**
+	 * Test if updateLink() can correctly creates a Link.
+	 */
+	@Test
+	public void testUpdateLink_Create() {
+		Link linkToCreate = createFeasibleLink();
+		Link linkToVerify = createFeasibleLink();
+		
+		//Use the link storage API to add the link
+		linkStorage.updateLink(linkToCreate, null, ILinkStorage.DM_OPERATION.CREATE);
+		doTestLinkExist(linkToVerify);
+	}
+	
+	/**
+	 * Test if updateLink() can correctly inserts a Link.
+	 */
+	@Test
+	public void testUpdateLink_Insert() {
+		Link linkToInsert = createFeasibleLink();
+		Link linkToVerify = createFeasibleLink();
+		
+		//Use the link storage API to add the link
+		linkStorage.updateLink(linkToInsert, null, ILinkStorage.DM_OPERATION.INSERT);
+
+		doTestLinkExist(linkToVerify);
+	}
+	
+	// TODO: Check if addOrUpdateLink() should accept DELETE operation. If not, remove this test.
+	/**
+	 * Test if updateLink() can correctly deletes a Link.
+	 */
+	@Ignore @Test
+	public void testUpdateLink_Delete() {
+		Link linkToDelete = createExistingLink();
+		Link linkToVerify = createExistingLink();
+
+		// Test deletion of existing link
+		linkStorage.updateLink(linkToDelete, null, DM_OPERATION.DELETE);
+		doTestLinkNotExist(linkToVerify);
+		
+		linkToDelete = createFeasibleLink();
+		linkToVerify = createFeasibleLink();
+
+		// Test deletion of not-existing link
+		linkStorage.updateLink(linkToDelete, null, DM_OPERATION.DELETE);
+		doTestLinkNotExist(linkToVerify);
+	}
+	
+	/**
+	 * Test if getLinks() can correctly return Links connected to specific DPID and port.
+	 */
+	@Test
+	public void testGetLinks_ByDpidPort(){
+		Link linkToVerify = createExistingLink();
+		Long dpid = linkToVerify.getSrc();
+		short port = (short)linkToVerify.getSrcPort();
+		
+		List<Link> list = linkStorage.getLinks(dpid, port);
 		
 		assertEquals(list.size(), 1);
 		
 		Link l = list.get(0);
-		assertEquals(l.getSrc(), 2561L);
-		assertEquals(l.getSrcPort(), (short)2);
-		assertEquals(l.getDst(), 2563L);
-		assertEquals(l.getDstPort(), (short)1);
+		assertEquals(l.getSrc(), linkToVerify.getSrc());
+		assertEquals(l.getSrcPort(), linkToVerify.getSrcPort());
+		assertEquals(l.getDst(), linkToVerify.getDst());
+		assertEquals(l.getDstPort(), linkToVerify.getDstPort());
+		
+		Link linkToVerifyNot = createFeasibleLink();
+		
+		List<Link> list2 = linkStorage.getLinks(linkToVerifyNot.getSrc(), (short)linkToVerifyNot.getSrcPort());
+		
+		assertEquals(list2.size(), 0);
 	}
 	
-	//TODO enable once method is written
-	@Ignore @Test
-	public void testUpdateDelete(){
-		Link linkToDelete = new Link(Long.decode("0x0000000000000a01"), 2, Long.decode("0x0000000000000a03"), 1);
+	/**
+	 * Test if getLinks() can correctly return Links connected to specific MAC address.
+	 */
+	@Test
+	public void testGetLinks_ByString() {
+		Link linkToVeryfy = createExistingLink();
+		String dpid = HexString.toHexString(linkToVeryfy.getSrc());
 		
-		linkStorage.update(linkToDelete, DM_OPERATION.DELETE);
-		
-		//Test if it was deleted correctly with the Gremlin API
-		GremlinPipeline<Vertex, Vertex> pipe = new GremlinPipeline<Vertex, Vertex>();
-		Iterator<Vertex> it = titanGraph.getVertices("dpid", "00:00:00:00:00:00:0a:01").iterator();
-		
-		assertTrue(it.hasNext());
-		Vertex sw1 = it.next();
-		assertFalse(it.hasNext());
-		
-		pipe.start(sw1).out("on").has("number", 2).out("link");
-		
-		assertFalse(pipe.hasNext());
+		List<Link> links = linkStorage.getLinks(dpid);
+		assertTrue(links.contains(linkToVeryfy));
+
+		Link linkToVerifyNot = createFeasibleLink();
+		assertFalse(links.contains(linkToVerifyNot));
 	}
 	
-	//TODO enable once method is written
-	@Ignore @Test
+	/**
+	 * Test if deleteLink() can correctly delete a Link.
+	 */
+	@Test
+	public void testDeleteLink() {
+		// Deletion of existing link
+		Link linkToDelete = createExistingLink();
+		Link linkToVerify = createExistingLink();
+		
+		linkStorage.deleteLink(linkToDelete);
+		doTestLinkNotExist(linkToVerify);
+	}
+	
+	/**
+	 * Test if deleteLinks() can correctly delete Links.
+	 */
+	@Test
 	public void testDeleteLinks(){
-		//TODO Make sure this works when the implementation is written
+		List<Link> linksToDelete = createExistingLinks();
+		List<Link> linksToVerify = createExistingLinks();
 		
-		linkStorage.deleteLinksOnPort(Long.decode("0x0000000000000a01"), (short)2);
-		
-		//Test if it was deleted correctly with the Gremlin API
-		GremlinPipeline<Vertex, Vertex> pipe = new GremlinPipeline<Vertex, Vertex>();
-		Iterator<Vertex> it = titanGraph.getVertices("dpid", "00:00:00:00:00:00:0a:01").iterator();
-		
-		assertTrue(it.hasNext());
-		Vertex sw1 = it.next();
-		assertFalse(it.hasNext());
-		
-		pipe.start(sw1).out("on").has("number", 2).out("link");
-		
-		assertFalse(pipe.hasNext());
+		linkStorage.deleteLinks(linksToDelete);
+		for(Link l : linksToVerify) {
+			doTestLinkNotExist(l);
+		}
 	}
 	
+	/**
+	 * Test if deleteLinks() can handle mixture of normal/abnormal input.
+	 */
+	@Ignore @Test
+	public void testDeleteLinks_Mixture(){
+		List<Link> linksToDelete = new ArrayList<Link>();
+		linksToDelete.add(createFeasibleLink());
+		linksToDelete.add(createExistingLink());
+		
+		// Test deletion of mixture of new/existing links
+		linkStorage.deleteLinks(linksToDelete);
+		doTestLinkNotExist(createFeasibleLink());
+		doTestLinkNotExist(createExistingLink());
+	}
+
+	/**
+	 * Test if getActiveLinks() can correctly return active Links.
+	 */
+	@Test
+	public void testGetActiveLinks() {
+		Link existingLink = createExistingLink();
+		Link notExistingLink = createFeasibleLink();
+
+		List<Link> links = linkStorage.getActiveLinks();
+		
+		assertTrue(links.contains(existingLink));
+		assertFalse(links.contains(notExistingLink));
+	}
+	
+	/**
+	 * Test if deleteLinksOnPort() can delete Links.
+	 */
+	@Test
+	public void testDeleteLinksOnPort() {
+		Link linkToDelete = createExistingLink();
+		Link linkToVerify = createExistingLink();
+		
+		linkStorage.deleteLinksOnPort(linkToDelete.getSrc(), linkToDelete.getSrcPort());
+		
+		doTestLinkNotExist(linkToVerify);
+	}
+
+	/**
+	 * Test if specific link is existing
+	 * @param link 
+	 */
+	private void doTestLinkExist(Link link) {
+		assertTrue(ope.hasLinkBetween(HexString.toHexString(link.getSrc()),
+				link.getSrcPort(),
+				HexString.toHexString(link.getDst()),
+				link.getDstPort()));
+	}
+	
+	/**
+	 * Test if titanGraph doesn't have specific link
+	 * @param link
+	 */
+	private void doTestLinkNotExist(Link link) {
+		assertFalse(ope.hasLinkBetween(HexString.toHexString(link.getSrc()),
+				link.getSrcPort(),
+				HexString.toHexString(link.getDst()),
+				link.getDstPort()));
+	}
+	
+	/**
+	 * Test if titanGraph has specific Link with specific LinkInfo
+	 * @param link 
+	 */
+	private void doTestLinkHasStateOf(Link link, LinkInfo info) {
+	}
+	
+	//----------------- Creation of test data -----------------------
+	// Assume a network shown below.
+	//
+	// [dpid1]--+--[port:1]----[port:1]--+--[dpid2]
+	//          |                        |
+	//          +--[port:2]    [port:2]--+
+	//          |
+	//          +--[port:3]    [port:1]--+--[dpid3]
+	//          |                        |
+	//          +--[port:4]----[port:2]--+
+	//
+	// dpid1 : 00:00:00:00:0a:01
+	// dpid2 : 00:00:00:00:0a:02
+	// dpid3 : 00:00:00:00:0a:03
+	
+	private void initLinks() {
+		final String dpid1 = "00:00:00:00:0a:01";
+		final String dpid2 = "00:00:00:00:0a:02";
+		final String dpid3 = "00:00:00:00:0a:03";
+		
+		ope.createNewSwitchForTest(dpid1).setStateForTest("ACTIVE");
+		ope.createNewSwitchForTest(dpid2).setStateForTest("ACTIVE");
+		ope.createNewSwitchForTest(dpid3).setStateForTest("ACTIVE");
+
+		TestPortObject ports1 [] = {
+				ope.createNewPortForTest(dpid1, (short)1),
+				ope.createNewPortForTest(dpid1, (short)2),
+				ope.createNewPortForTest(dpid1, (short)3),
+				ope.createNewPortForTest(dpid1, (short)4),
+		};
+
+		TestPortObject ports2 [] = {
+				ope.createNewPortForTest(dpid2, (short)1),
+				ope.createNewPortForTest(dpid2, (short)2),
+		};
+
+		TestPortObject ports3 [] = {
+				ope.createNewPortForTest(dpid3, (short)1),
+				ope.createNewPortForTest(dpid3, (short)2),
+		};
+		
+		ope.setLinkBetweenPortsForTest(ports1[0], ports2[0]);
+		ope.setLinkBetweenPortsForTest(ports1[3], ports3[1]);
+	}
+	
+	/**
+	 * Returns new Link object of existing link
+	 * @return new Link object
+	 */
+	private Link createExistingLink() {
+		return new Link(Long.decode("0x0000000000000a01"), 1, Long.decode("0x0000000000000a02"), 1);
+	}
+	
+	/**
+	 * Returns new Link object of not-existing but feasible link
+	 * @return new Link object
+	 */
+	private Link createFeasibleLink() {
+		return new Link(Long.decode("0x0000000000000a01"), 3, Long.decode("0x0000000000000a03"), 1);
+	}
+	
+	// make NO sense while test-network data doesn't define physical network (i.e. any link is feasible)
+	@SuppressWarnings("unused")
+	private Link createInfeasibleLink() {
+		return new Link(Long.decode("0x0000000000000a01"), 1, Long.decode("0x0000000000000a03"), 3);
+	}
+
+	/**
+	 * Returns list of Link objects which all has information of existing link in titanGraph
+	 * @return ArrayList of new Link objects
+	 */
+	private List<Link> createExistingLinks() {
+		List<Link> links = new ArrayList<Link>();
+		links.add(new Link(Long.decode("0x0000000000000a01"), 1, Long.decode("0x0000000000000a02"), 1));
+		links.add(new Link(Long.decode("0x0000000000000a01"), 4, Long.decode("0x0000000000000a03"), 2));
+		return links;
+	}
+	
+	/**
+	 * Returns list of Link objects which all has information of not-existing but feasible link
+	 * @return ArrayList of new Link objects
+	 */
+	private List<Link> createFeasibleLinks() {
+		List<Link> links = new ArrayList<Link>();
+		links.add(new Link(Long.decode("0x0000000000000a01"), 2, Long.decode("0x0000000000000a02"), 2));
+		links.add(new Link(Long.decode("0x0000000000000a01"), 3, Long.decode("0x0000000000000a03"), 1));
+		return links;
+	}
+	
+	/**
+	 * Returns new LinkInfo object with convenient values.
+	 * @return LinkInfo object
+	 */
+	private LinkInfo createFeasibleLinkInfo(long time) {
+		long time_first = time;
+		long time_last_lldp = time + 50;
+		long time_last_bddp = time + 100;
+		int state_src = OFPhysicalPort.OFPortState.OFPPS_STP_FORWARD.getValue();
+		int state_dst = OFPhysicalPort.OFPortState.OFPPS_STP_LISTEN.getValue();
+
+		return new LinkInfo(time_first,
+				time_last_lldp,
+				time_last_bddp,
+				state_src,
+				state_dst);
+	}
+	//---------------------------------------------------------------
 }
diff --git a/src/test/java/net/onrc/onos/ofcontroller/core/internal/TestDatabaseManager.java b/src/test/java/net/onrc/onos/ofcontroller/core/internal/TestDatabaseManager.java
index eea586b..b4cfc31 100644
--- a/src/test/java/net/onrc/onos/ofcontroller/core/internal/TestDatabaseManager.java
+++ b/src/test/java/net/onrc/onos/ofcontroller/core/internal/TestDatabaseManager.java
@@ -73,4 +73,4 @@
 		}
 	}
 	
-}
+}
\ No newline at end of file
diff --git a/src/test/java/net/onrc/onos/ofcontroller/core/internal/TestableGraphDBOperation.java b/src/test/java/net/onrc/onos/ofcontroller/core/internal/TestableGraphDBOperation.java
new file mode 100644
index 0000000..31a4bb0
--- /dev/null
+++ b/src/test/java/net/onrc/onos/ofcontroller/core/internal/TestableGraphDBOperation.java
@@ -0,0 +1,1331 @@
+package net.onrc.onos.ofcontroller.core.internal;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.easymock.EasyMock;
+import org.openflow.util.HexString;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.tinkerpop.blueprints.Vertex;
+import com.tinkerpop.frames.annotations.gremlin.GremlinParam;
+
+import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.IDeviceObject;
+import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.IFlowEntry;
+import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.IFlowPath;
+import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.IPortObject;
+import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.ISwitchObject;
+import net.onrc.onos.ofcontroller.util.FlowEntryId;
+import net.onrc.onos.ofcontroller.util.FlowId;
+import net.onrc.onos.util.GraphDBConnection;
+import net.onrc.onos.util.GraphDBOperation;
+import net.onrc.onos.util.IDBConnection;
+
+/**
+ * Mock class of GraphDBOperation which provides additional setter to construct a graph for test.
+ * This object simply caches parameters set up by override interfaces and reflect them when commit().
+ * *ForTest() methods are exempt from cache, parameters through those methods are reflected soon.
+ * @author Naoki Shiota
+ *
+ */
+public class TestableGraphDBOperation extends GraphDBOperation {
+	protected static Logger log = LoggerFactory.getLogger(TestableGraphDBOperation.class);
+
+	protected List<TestSwitchObject> switches;
+	protected List<TestPortObject> ports;
+	protected List<TestDeviceObject> devices;
+	protected List<TestFlowPath> paths;
+	protected List<TestFlowEntry> entries;
+
+	protected List<TestSwitchObject> switchesToAdd;
+	protected List<TestPortObject> portsToAdd;
+	protected List<TestDeviceObject> devicesToAdd;
+	protected List<TestFlowPath> pathsToAdd;
+	protected List<TestFlowEntry> entriesToAdd;
+
+	protected List<TestSwitchObject> switchesToRemove;
+	protected List<TestPortObject> portsToRemove;
+	protected List<TestDeviceObject> devicesToRemove;
+	protected List<TestFlowPath> pathsToRemove;
+	protected List<TestFlowEntry> entriesToRemove;
+
+	// Testable implementations of INetMapTopologyObject interfaces
+
+	public static class TestSwitchObject implements ISwitchObject {
+		private String state,type,dpid;
+		private List<IPortObject> ports;
+		private List<IDeviceObject> devices;
+		private List<IFlowEntry> entries;
+
+		private String stateToUpdate, typeToUpdate, dpidToUpdate;
+		private List<IPortObject> portsToAdd;
+		private List<IPortObject> portsToRemove;
+
+		public TestSwitchObject() {
+			type = "switch";
+			
+			ports = new ArrayList<IPortObject>();
+			portsToAdd = new ArrayList<IPortObject>();
+			portsToRemove = new ArrayList<IPortObject>();
+			devices = new ArrayList<IDeviceObject>();
+			entries = new ArrayList<IFlowEntry>();
+			
+			clearUncommitedData();
+		}
+		
+		public void commit() {
+			for(IPortObject port : portsToAdd) {
+				ports.add(port);
+			}
+			for(IPortObject port : portsToRemove) {
+				ports.remove(port);
+			}
+			if(stateToUpdate != null) { state = stateToUpdate; }
+			if(typeToUpdate != null) { type = typeToUpdate; }
+			if(dpidToUpdate != null) { dpid = dpidToUpdate; }
+
+			clearUncommitedData();
+		}
+		
+		public void rollback() {
+			clearUncommitedData();
+		}
+		
+		public void clearUncommitedData() {
+			portsToAdd.clear();
+			portsToRemove.clear();
+			stateToUpdate = typeToUpdate = dpidToUpdate = null;
+		}
+		
+		public void setStateForTest(String state) { this.state = state; }
+		public void setTypeForTest(String type) { this.type = type; }
+		public void setDpidForTest(String dpid) { this.dpid = dpid; }
+		public void addPortForTest(TestPortObject port) { ports.add(port);  }
+		public void addDeviceForTest(TestDeviceObject dev) { devices.add(dev); }
+		public void addEntryForTest(TestFlowEntry entry) { entries.add(entry); }
+		
+		@Override
+		public String getState() { return state; }
+	
+		@Override
+		public void setState(String state) { this.stateToUpdate = state; }
+	
+		@Override
+		public String getType() { return type ; }
+	
+		@Override
+		public void setType(String type) { this.typeToUpdate = type; }
+	
+		// Not support for test
+		@Override
+		public Vertex asVertex() { return null; }
+	
+		@Override
+		public String getDPID() { return dpid; }
+	
+		@Override
+		public void setDPID(String dpid) { this.dpidToUpdate = dpid; }
+	
+		@Override
+		public Iterable<IPortObject> getPorts() { return ports; }
+	
+		@Override
+		public IPortObject getPort(@GremlinParam("port_num") short port_num) {
+			for(IPortObject port : ports) {
+				if(port.getNumber() == port_num) {
+					return port;
+				}
+			}
+			return null;
+		}
+	
+		@Override
+		public void addPort(IPortObject port) { portsToAdd.add(port); }
+	
+		@Override
+		public void removePort(IPortObject port) { portsToRemove.add(port); }
+	
+		@Override
+		public Iterable<IDeviceObject> getDevices() { return devices; }
+	
+		@Override
+		public Iterable<IFlowEntry> getFlowEntries() { return entries; }
+	}
+	
+	public static class TestPortObject implements IPortObject {
+		private String state,type,desc;
+		private Short number;
+		private Integer port_state;
+		private ISwitchObject sw;
+		
+		private List<IPortObject> linkedPorts;
+		private List<IDeviceObject> devices;
+		private List<IFlowEntry> inflows,outflows;
+		
+		private String stateToUpdate,typeToUpdate,descToUpdate;
+		private Short numberToUpdate;
+		private Integer port_stateToUpdate;
+		
+		private List<IPortObject> linkedPortsToAdd;
+		private List<IPortObject> linkedPortsToRemove;
+		private List<IDeviceObject> devicesToAdd;
+		private List<IDeviceObject> devicesToRemove;
+		
+
+		public TestPortObject() {
+			type = "port";
+
+			linkedPorts = new ArrayList<IPortObject>();
+			linkedPortsToAdd = new ArrayList<IPortObject>();
+			linkedPortsToRemove = new ArrayList<IPortObject>();
+			devices = new ArrayList<IDeviceObject>();
+			devicesToAdd = new ArrayList<IDeviceObject>();
+			devicesToRemove = new ArrayList<IDeviceObject>();
+			inflows = new ArrayList<IFlowEntry>();
+			outflows = new ArrayList<IFlowEntry>();
+			
+			clearUncommitedData();
+		}
+		
+		public void commit() {
+			for(IPortObject port : linkedPortsToAdd) { linkedPorts.add(port); }
+			for(IPortObject port : linkedPortsToRemove) { linkedPorts.remove(port); }
+			for(IDeviceObject dev : devicesToAdd) { devices.add(dev); }
+			for(IDeviceObject dev : devicesToRemove) { devices.remove(dev); }
+			
+			if(stateToUpdate != null) { state = stateToUpdate; }
+			if(typeToUpdate != null) { type = typeToUpdate; }
+			if(descToUpdate != null) { desc = descToUpdate; }
+			if(numberToUpdate != null) { number = numberToUpdate; }
+			if(port_stateToUpdate != null) { port_state = port_stateToUpdate; }
+			
+			clearUncommitedData();
+		}
+		
+		public void rollback() {
+			clearUncommitedData();
+		}
+		
+		public void clearUncommitedData() {
+			linkedPortsToAdd.clear();
+			linkedPortsToRemove.clear();
+			devicesToAdd.clear();
+			devicesToRemove.clear();
+			stateToUpdate = typeToUpdate = descToUpdate = null;
+			port_stateToUpdate = null;
+			numberToUpdate = null;
+		}
+		
+		// Setter methods for test
+		public void setStateForTest(String state) { this.state = state; }
+		public void setTypeForTest(String type) { this.type = type; }
+		public void setDescForTest(String desc) { this.desc = desc; }
+		public void setNumberForTest(Short number) { this.number = number; }
+		public void setPortStateForTest(Integer state) { this.port_state = state; }
+		public void setSwitchForTest(ISwitchObject sw) { this.sw = sw; }
+		public void addLinkedPortForTest(TestPortObject port) { this.linkedPorts.add(port); }
+		public void addInflowForTest(TestFlowEntry entry) { inflows.add(entry); }
+		public void addOutflowForTest(TestFlowEntry entry) { outflows.add(entry); }
+		
+		// Override methods for mock IPortObject
+		@Override
+		public String getState() { return state; }
+
+		@Override
+		public void setState(String state) { this.stateToUpdate = state; }
+
+		@Override
+		public String getType() { return type; }
+
+		@Override
+		public void setType(String type) { this.typeToUpdate = type; }
+
+		// not support for test
+		@Override
+		public Vertex asVertex() {
+			return null;
+		}
+
+		@Override
+		public Short getNumber() { return number; }
+
+		@Override
+		public void setNumber(Short n) { this.numberToUpdate = n; }
+
+		@Override
+		public String getDesc() { return desc; }
+
+		@Override
+		public void setDesc(String s) { this.descToUpdate = s; }
+
+		@Override
+		public Integer getPortState() { return port_state; }
+
+		@Override
+		public void setPortState(Integer s) { this.port_stateToUpdate = s; }
+
+		@Override
+		public ISwitchObject getSwitch() { return sw; }
+
+		@Override
+		public Iterable<IDeviceObject> getDevices() { return devices; }
+
+		@Override
+		public void setDevice(IDeviceObject device) { devicesToAdd.add(device); }
+
+		@Override
+		public void removeDevice(IDeviceObject device) { devicesToRemove.add(device); }
+
+		@Override
+		public Iterable<IFlowEntry> getInFlowEntries() { return inflows; }
+
+		@Override
+		public Iterable<IFlowEntry> getOutFlowEntries() { return outflows; }
+
+		@Override
+		public Iterable<IPortObject> getLinkedPorts() { return linkedPorts; }
+
+		@Override
+		public void removeLink(IPortObject dest_port) { linkedPortsToRemove.add(dest_port); }
+
+		@Override
+		public void setLinkPort(IPortObject dest_port) { linkedPortsToAdd.add(dest_port); }
+	}
+		
+	public static class TestDeviceObject implements IDeviceObject {
+		private String state,type,mac,ipaddr;
+		private List<IPortObject> ports;
+		private List<ISwitchObject> switches;
+		
+		private String stateToUpdate,typeToUpdate,macToUpdate,ipaddrToUpdate;
+		private List<IPortObject> portsToAdd;
+		private List<IPortObject> portsToRemove;
+	
+		public TestDeviceObject() {
+			type = "device";
+			
+			ports = new ArrayList<IPortObject>();
+			portsToAdd = new ArrayList<IPortObject>();
+			portsToRemove = new ArrayList<IPortObject>();
+			switches = new ArrayList<ISwitchObject>();
+			
+			clearUncommitedData();
+		}
+		
+		public void commit() {
+			for(IPortObject port : portsToAdd) {
+				ports.add(port);
+			}
+			for(IPortObject port : portsToRemove) {
+				ports.remove(port);
+			}
+			
+			if(stateToUpdate != null) { state = stateToUpdate; }
+			if(typeToUpdate != null) { type = typeToUpdate; }
+			if(macToUpdate != null) { mac = macToUpdate; }
+			if(ipaddrToUpdate != null) { ipaddr = ipaddrToUpdate; }
+			
+			clearUncommitedData();
+		}
+		
+		public void rollback() {
+			clearUncommitedData();
+		}
+		
+		public void clearUncommitedData() {
+			ports.clear();
+			portsToAdd.clear();
+			portsToRemove.clear();
+			
+			stateToUpdate = typeToUpdate = macToUpdate = ipaddrToUpdate = null;
+		}
+		
+		// Setter methods for test
+		public void setStateForTest(String state) { this.state = state; }
+		public void setTypeForTest(String type) { this.type = type; }
+		public void setMacForTest(String mac) { this.mac = mac; }
+		public void setIpaddrForTest(String ipaddr) { this.ipaddr = ipaddr; }
+		public void addSwitchForTest(ISwitchObject sw) { switches.add(sw); }
+		public void addPortForTest(IPortObject port) { ports.add(port); }
+		
+		
+		// Override methods
+		@Override
+		public String getState() { return state; }
+	
+		@Override
+		public void setState(String state) { stateToUpdate = state; }
+	
+		@Override
+		public String getType() { return type; }
+	
+		@Override
+		public void setType(String type) { typeToUpdate = type; }
+	
+		@Override
+		public Vertex asVertex() {
+			// TODO Auto-generated method stub
+			return null;
+		}
+	
+		@Override
+		public String getMACAddress() { return mac; }
+	
+		@Override
+		public void setMACAddress(String macaddr) { macToUpdate = macaddr; }
+	
+		@Override
+		public String getIPAddress() { return ipaddr; }
+	
+		@Override
+		public void setIPAddress(String ipaddr) { ipaddrToUpdate = ipaddr; }
+	
+		@Override
+		public Iterable<IPortObject> getAttachedPorts() {
+			return ports; }
+	
+		@Override
+		public void setHostPort(IPortObject port) { portsToAdd.add(port); }
+	
+		@Override
+		public void removeHostPort(IPortObject port) { portsToRemove.add(port); }
+	
+		@Override
+		public Iterable<ISwitchObject> getSwitch() { return switches; }
+	}
+	
+	public static class TestFlowPath implements IFlowPath {
+		private String state,type,flowId,installerId,srcSw,dstSw;
+		private String dataPathSummary,userState;
+		private String matchSrcMac,matchDstMac,matchSrcIpaddr,matchDstIpaddr;
+		private Short srcPort,dstPort,matchEthernetFrameType;
+		
+		private List<IFlowEntry> entries;
+		private List<ISwitchObject> switches;
+
+		private String stateToUpdate,typeToUpdate,flowIdToUpdate,installerIdToUpdate,srcSwToUpdate,dstSwToUpdate;
+		private String dataPathSummaryToUpdate,userStateToUpdate;
+		private String matchSrcMacToUpdate,matchDstMacToUpdate,matchSrcIpaddrToUpdate,matchDstIpaddrToUpdate;
+		private Short srcPortToUpdate,dstPortToUpdate,matchEthernetFrameTypeToUpdate;
+
+		private List<IFlowEntry> flowsToAdd;
+		private List<IFlowEntry> flowsToRemove;
+
+		public TestFlowPath() {
+			type = "flow";
+			
+			entries = new ArrayList<IFlowEntry>();
+			flowsToAdd = new ArrayList<IFlowEntry>();
+			flowsToRemove = new ArrayList<IFlowEntry>();
+			
+			switches = new ArrayList<ISwitchObject>();
+			
+			clear();
+		}
+		
+		public void commit() {
+			for(IFlowEntry flow : flowsToAdd) {
+				entries.add(flow);
+			}
+			for(IFlowEntry flow : flowsToRemove) {
+				entries.remove(flow);
+			}
+			if(stateToUpdate != null) { state = stateToUpdate; }
+			if(typeToUpdate != null) { type = typeToUpdate; }
+			if(flowIdToUpdate != null) { flowId = flowIdToUpdate; }
+			if(installerIdToUpdate != null) { installerId = installerIdToUpdate; }
+			if(srcSwToUpdate != null) { srcSw = srcSwToUpdate; }
+			if(dstSwToUpdate != null) { dstSw = dstSwToUpdate; }
+			if(dataPathSummaryToUpdate != null) { dataPathSummary = dataPathSummaryToUpdate; }
+			if(userStateToUpdate != null) { userState = userStateToUpdate; }
+			if(matchSrcMacToUpdate != null) { matchSrcMac = matchSrcMacToUpdate; }
+			if(matchDstMacToUpdate != null) { matchDstMac = matchDstMacToUpdate; }
+			if(matchSrcIpaddrToUpdate != null) { matchSrcIpaddr = matchSrcIpaddrToUpdate; }
+			if(matchDstIpaddrToUpdate != null) { matchDstIpaddr = matchDstIpaddrToUpdate; }
+			if(srcPortToUpdate != null) { srcPort = srcPortToUpdate; }
+			if(dstPortToUpdate != null) { dstPort = dstPortToUpdate; }
+			if(matchEthernetFrameTypeToUpdate != null) { matchEthernetFrameType = matchEthernetFrameTypeToUpdate; }
+		}
+		
+		public void rollback() {
+			clear();
+		}
+		
+		public void clear() {
+			flowsToAdd.clear();
+			flowsToRemove.clear();
+			
+			stateToUpdate = typeToUpdate = flowIdToUpdate = installerIdToUpdate = null;
+			srcSwToUpdate = dstSwToUpdate = dataPathSummaryToUpdate = userStateToUpdate = null;
+			matchSrcMacToUpdate = matchDstMacToUpdate = matchSrcIpaddrToUpdate = matchDstIpaddrToUpdate = null;
+			srcPortToUpdate = dstPortToUpdate = matchEthernetFrameTypeToUpdate = null;
+		}
+		
+		// Setter methods for test
+		public void setStateForTest(String state) { this.state = state; }
+		public void setTypeForTest(String type) { this.type = type; }
+		public void setFlowIdForTest(String flowId) { this.flowId = flowId; }
+		public void setInstallerIdForTest(String installerId) { this.installerId = installerId; }
+		public void setSrcSwForTest(String srcSw) { this.srcSw = srcSw; }
+		public void setDstSwForTest(String dstSw) { this.dstSw = dstSw; }
+		public void setDataPathSummaryForTest(String dataPathSummary) { this.dataPathSummary = dataPathSummary; }
+		public void setUserStateForTest(String userState) { this.userState = userState; }
+		public void setMatchSrcMacForTest(String matchSrcMac) { this.matchSrcMac = matchSrcMac; }
+		public void setMatchDstMacForTest(String matchDstMac) { this.matchDstMac = matchDstMac; }
+		public void setMatchSrcIpaddrForTest(String matchSrcIpaddr) { this.matchSrcIpaddr = matchSrcIpaddr; }
+		public void setMatchDstIpaddrForTest(String matchDstIpaddr) { this.matchDstIpaddr = matchDstIpaddr; }
+		public void setSrcPortForTest(Short srcPort) { this.srcPort = srcPort; }
+		public void setDstPortForTest(Short dstPort) { this.dstPort = dstPort; }
+		public void setMatchEthernetFrameTypeForTest(Short matchEthernetFrameType) { this.matchEthernetFrameType = matchEthernetFrameType; }
+		public void addFlowEntryForTest(IFlowEntry entry) { entries.add(entry); }
+		public void addSwitchForTest(ISwitchObject sw) { switches.add(sw); }
+
+		@Override
+		public String getState() { return state; }
+
+		@Override
+		public void setState(String state) { stateToUpdate = state; }
+
+		@Override
+		public String getType() { return type; }
+
+		@Override
+		public void setType(String type) { typeToUpdate = type; }
+
+		@Override
+		public Vertex asVertex() {
+			// TODO Auto-generated method stub
+			return null;
+		}
+
+		@Override
+		public String getFlowId() { return flowId; }
+
+		@Override
+		public void setFlowId(String flowId) { flowIdToUpdate = flowId; }
+
+		@Override
+		public String getInstallerId() { return installerId; }
+
+		@Override
+		public void setInstallerId(String installerId) { installerIdToUpdate = installerId; }
+
+		@Override
+		public String getSrcSwitch() { return srcSw; }
+
+		@Override
+		public void setSrcSwitch(String srcSwitch) { srcSwToUpdate = srcSwitch; }
+
+		@Override
+		public Short getSrcPort() { return srcPort; }
+
+		@Override
+		public void setSrcPort(Short srcPort) { srcPortToUpdate = srcPort; }
+
+		@Override
+		public String getDstSwitch() { return dstSw; }
+
+		@Override
+		public void setDstSwitch(String dstSwitch) { dstSwToUpdate = dstSwitch; }
+
+		@Override
+		public Short getDstPort() { return dstPort; }
+
+		@Override
+		public void setDstPort(Short dstPort) { dstPortToUpdate = dstPort; }
+
+		@Override
+		public String getDataPathSummary() { return dataPathSummary; }
+
+		@Override
+		public void setDataPathSummary(String dataPathSummary) { dataPathSummaryToUpdate = dataPathSummary; }
+
+		@Override
+		public Iterable<IFlowEntry> getFlowEntries() { return entries; }
+
+		@Override
+		public void addFlowEntry(IFlowEntry flowEntry) {
+			if(! entries.contains(flowEntry)) {
+				flowsToAdd.add(flowEntry);
+			}
+		}
+
+		@Override
+		public void removeFlowEntry(IFlowEntry flowEntry) {
+			if(entries.contains(flowEntry)) {
+				flowsToAdd.add(flowEntry);
+			}
+		}
+
+		@Override
+		public Short getMatchEthernetFrameType() { return matchEthernetFrameType; }
+
+		@Override
+		public void setMatchEthernetFrameType(Short matchEthernetFrameType) {
+			matchEthernetFrameTypeToUpdate = matchEthernetFrameType; }
+
+		@Override
+		public String getMatchSrcMac() { return matchSrcMac; }
+
+		@Override
+		public void setMatchSrcMac(String matchSrcMac) { matchSrcMacToUpdate = matchSrcMac; }
+
+		@Override
+		public String getMatchDstMac() { return matchDstMac; }
+
+		@Override
+		public void setMatchDstMac(String matchDstMac) { matchDstMacToUpdate = matchDstMac; }
+
+		@Override
+		public String getMatchSrcIPv4Net() { return matchSrcIpaddr; }
+
+		@Override
+		public void setMatchSrcIPv4Net(String matchSrcIPv4Net) {
+			matchSrcIpaddrToUpdate = matchSrcIPv4Net; }
+
+		@Override
+		public String getMatchDstIPv4Net() { return matchDstIpaddr; }
+
+		@Override
+		public void setMatchDstIPv4Net(String matchDstIPv4Net) {
+			matchDstIpaddrToUpdate = matchDstIPv4Net; }
+
+		@Override
+		public Iterable<ISwitchObject> getSwitches() { return switches; }
+
+		@Override
+		public String getUserState() { return userState; }
+
+		@Override
+		public void setUserState(String userState) { userStateToUpdate = userState; }
+	}
+
+	public static class TestFlowEntry implements IFlowEntry {
+		private String state,type,entryId,dpid,userState,switchState,errorStateType,errorStateCode;
+		private String matchSrcMac,matchDstMac,matchSrcIpaddr,matchDstIpaddr;
+		private Short matchInPort,matchEtherFrameType,actionOutput;
+		
+		private IFlowPath flowPath;
+		private ISwitchObject sw;
+		private IPortObject inport,outport;
+	
+		private String stateToUpdate,typeToUpdate,entryIdToUpdate,dpidToUpdate,
+			userStateToUpdate,switchStateToUpdate,errorStateTypeToUpdate,errorStateCodeToUpdate;
+		private String matchSrcMacToUpdate,matchDstMacToUpdate,matchSrcIpaddrToUpdate,matchDstIpaddrToUpdate;
+	
+		private Short matchInPortToUpdate,matchEtherFrameTypeToUpdate,actionOutputToUpdate;
+	
+		private IFlowPath flowPathToUpdate;
+		private ISwitchObject swToUpdate;
+		private IPortObject inportToUpdate,outportToUpdate;
+	
+		public TestFlowEntry() {
+			type = "flow_entry";
+			
+			clearUncommitedData();
+		}
+		
+		public void commit() {
+			if(stateToUpdate != null) { state = stateToUpdate; }
+			if(typeToUpdate != null) { type = typeToUpdate; }
+			if(entryIdToUpdate != null) { entryId = entryIdToUpdate; }
+			if(dpidToUpdate != null) { dpid = dpidToUpdate; }
+			if(userStateToUpdate != null) { userState = userStateToUpdate; }
+			if(switchStateToUpdate != null) { switchState = switchStateToUpdate; }
+			if(errorStateTypeToUpdate != null) { errorStateType = errorStateTypeToUpdate; }
+			if(errorStateCodeToUpdate != null) { errorStateCode = errorStateCodeToUpdate; }
+			if(matchSrcMacToUpdate != null) { matchSrcMac = matchSrcMacToUpdate; }
+			if(matchDstMacToUpdate != null) { matchDstMac = matchDstMacToUpdate; }
+			if(matchSrcIpaddrToUpdate != null) { matchSrcIpaddr = matchSrcIpaddrToUpdate; }
+			if(matchDstIpaddrToUpdate != null) { matchDstIpaddr = matchDstIpaddrToUpdate; }
+			if(matchInPortToUpdate != null) { matchInPort = matchInPortToUpdate; }
+			if(matchEtherFrameTypeToUpdate != null) { matchEtherFrameType = matchEtherFrameTypeToUpdate; }
+			if(actionOutputToUpdate != null) { actionOutput = actionOutputToUpdate; }
+			
+			if(flowPathToUpdate != null) { flowPath = flowPathToUpdate; }
+			if(swToUpdate != null) { sw = swToUpdate; }
+			if(inportToUpdate != null) { inport = inportToUpdate; }
+			if(outportToUpdate != null) { outport = outportToUpdate; }
+	
+			clearUncommitedData();
+		}
+		
+		public void rollback() {
+			clearUncommitedData();
+		}
+		
+		public void clearUncommitedData() {
+			stateToUpdate = typeToUpdate = entryIdToUpdate = dpidToUpdate = null;
+			userStateToUpdate = switchStateToUpdate = errorStateTypeToUpdate = errorStateCodeToUpdate = null;
+			matchSrcMacToUpdate = matchDstMacToUpdate = matchSrcIpaddrToUpdate = matchDstIpaddrToUpdate = null;
+			matchInPortToUpdate = matchEtherFrameTypeToUpdate = actionOutputToUpdate = null;
+			flowPathToUpdate = null;
+			swToUpdate = null;
+			inportToUpdate = outportToUpdate = null;
+		}
+		
+		// Setter methods for test
+		public void setStateForTest(String state) { this.state = state; }
+		public void setTypeForTest(String type) { this.type = type; }
+		public void setEntryIdForTest(String entryId) { this.entryId = entryId; }
+		public void setDpidForTest(String dpid) { this.dpid = dpid; }
+		public void setUserStateForTest(String userState) { this.userState = userState; }
+		public void setSwitchStateForTest(String switchState) { this.switchState = switchState; }
+		public void setErrorStateTypeForTest(String errorStateType) { this.errorStateType = errorStateType; }
+		public void setErrorStateCodeForTest(String errorStateCode) { this.errorStateCode = errorStateCode; }
+		public void setMatchSrcMacForTest(String matchSrcMac) { this.matchSrcMac = matchSrcMac; }
+		public void setMatchDstMacForTest(String matchDstMac) { this.matchDstMac = matchDstMac; }
+		public void setMatchSrcIpaddrForTest(String matchSrcIpaddr) { this.matchSrcIpaddr = matchSrcIpaddr; }
+		public void setMatchDstIpaddrForTest(String matchDstIpaddr) { this.matchDstIpaddr = matchDstIpaddr; }
+		public void setMatchInPortForTest(Short matchInPort) { this.matchInPort = matchInPort; }
+		public void setMatchEtherFrameTypeForTest(Short matchEtherFrameType) { this.matchEtherFrameType = matchEtherFrameType; }
+		public void setActionOutputForTest(Short actionOutput) { this.actionOutput = actionOutput; }
+		public void setFlowPathForTest(IFlowPath flowPath) { this.flowPath = flowPath; }
+		public void setSwitchForTest(ISwitchObject sw) { this.sw = sw; }
+		public void setInportForTest(IPortObject inport) { this.inport = inport; }
+		public void setOutportForTest(IPortObject outport) { this.outport = outport; }
+		
+		@Override
+		public String getState() { return state; }
+	
+		@Override
+		public void setState(String state) { stateToUpdate = state; }
+	
+		@Override
+		public String getType() { return type; }
+	
+		@Override
+		public void setType(String type) { typeToUpdate = type; }
+	
+		@Override
+		public Vertex asVertex() {
+			// TODO Auto-generated method stub
+			return null;
+		}
+	
+		@Override
+		public String getFlowEntryId() { return entryId; }
+	
+		@Override
+		public void setFlowEntryId(String flowEntryId) { entryIdToUpdate = flowEntryId; }
+	
+		@Override
+		public String getSwitchDpid() { return dpid; }
+	
+		@Override
+		public void setSwitchDpid(String switchDpid) { dpidToUpdate = switchDpid; }
+	
+		@Override
+		public String getUserState() { return userState; }
+	
+		@Override
+		public void setUserState(String userState) { userStateToUpdate = userState; }
+	
+		@Override
+		public String getSwitchState() { return switchState; }
+	
+		@Override
+		public void setSwitchState(String switchState) { switchStateToUpdate = switchState; }
+	
+		@Override
+		public String getErrorStateType() { return errorStateType; }
+	
+		@Override
+		public void setErrorStateType(String errorStateType) { errorStateTypeToUpdate = errorStateType; }
+	
+		@Override
+		public String getErrorStateCode() { return errorStateCode; }
+	
+		@Override
+		public void setErrorStateCode(String errorStateCode) { errorStateCodeToUpdate = errorStateCode; }
+	
+		@Override
+		public Short getMatchInPort() { return matchInPort; }
+	
+		@Override
+		public void setMatchInPort(Short matchInPort) { matchInPortToUpdate = matchInPort; }
+	
+		@Override
+		public Short getMatchEthernetFrameType() {return matchEtherFrameType; }
+	
+		@Override
+		public void setMatchEthernetFrameType(Short matchEthernetFrameType) { matchEtherFrameTypeToUpdate = matchEthernetFrameType; }
+		
+		@Override
+		public String getMatchSrcMac() { return matchSrcMac; }
+	
+		@Override
+		public void setMatchSrcMac(String matchSrcMac) { matchSrcMacToUpdate = matchSrcMac; }
+	
+		@Override
+		public String getMatchDstMac() { return matchDstMac; }
+	
+		@Override
+		public void setMatchDstMac(String matchDstMac) { matchDstMacToUpdate = matchDstMac; }
+	
+		@Override
+		public String getMatchSrcIPv4Net() { return matchSrcIpaddr; }
+	
+		@Override
+		public void setMatchSrcIPv4Net(String matchSrcIPv4Net) { matchSrcIpaddrToUpdate = matchSrcIPv4Net; }
+	
+		@Override
+		public String getMatchDstIPv4Net() { return matchDstIpaddr; }
+	
+		@Override
+		public void setMatchDstIPv4Net(String matchDstIPv4Net) { matchDstIpaddrToUpdate = matchDstIPv4Net; }
+	
+		@Override
+		public Short getActionOutput() { return actionOutput; }
+	
+		@Override
+		public void setActionOutput(Short actionOutput) { actionOutputToUpdate = actionOutput; }
+	
+		@Override
+		public IFlowPath getFlow() { return flowPath; }
+	
+		@Override
+		public void setFlow(IFlowPath flow) { flowPathToUpdate = flow; }
+	
+		@Override
+		public ISwitchObject getSwitch() { return sw; }
+	
+		@Override
+		public void setSwitch(ISwitchObject sw) { swToUpdate = sw; }
+	
+		@Override
+		public IPortObject getInPort() { return inport; }
+	
+		@Override
+		public void setInPort(IPortObject port) { inportToUpdate = port; }
+	
+		@Override
+		public IPortObject getOutPort() { return outport; }
+	
+		@Override
+		public void setOutPort(IPortObject port) { outportToUpdate = port; }
+	}
+
+
+	public TestableGraphDBOperation() {
+		super(EasyMock.createNiceMock(GraphDBConnection.class));
+		
+		switches = new ArrayList<TestSwitchObject>();
+		ports = new ArrayList<TestPortObject>();
+		devices = new ArrayList<TestDeviceObject>();
+		paths = new ArrayList<TestFlowPath>();
+		entries = new ArrayList<TestFlowEntry>();
+		
+		switchesToAdd = new ArrayList<TestSwitchObject>();
+		portsToAdd = new ArrayList<TestPortObject>();
+		devicesToAdd = new ArrayList<TestDeviceObject>();
+		pathsToAdd = new ArrayList<TestFlowPath>();
+		entriesToAdd = new ArrayList<TestFlowEntry>();
+
+		switchesToRemove = new ArrayList<TestSwitchObject>();
+		portsToRemove = new ArrayList<TestPortObject>();
+		devicesToRemove = new ArrayList<TestDeviceObject>();
+		pathsToRemove = new ArrayList<TestFlowPath>();
+		entriesToRemove = new ArrayList<TestFlowEntry>();
+		
+		clearUncommitedData();
+	}
+	
+	private void clearUncommitedData() {
+		for(TestFlowEntry flow : entries) {
+			flow.clearUncommitedData();
+		}
+		for(TestFlowEntry flow : entriesToAdd) {
+			flow.clearUncommitedData();
+		}
+		
+		for(TestDeviceObject dev : devices) {
+			dev.clearUncommitedData();
+		}
+		for(TestDeviceObject dev : devicesToAdd) {
+			dev.clearUncommitedData();
+		}
+		
+		for(TestSwitchObject sw : switches) {
+			sw.clearUncommitedData();
+		}
+		for(TestSwitchObject sw : switchesToAdd) {
+			sw.clearUncommitedData();
+		}
+		
+		for(TestPortObject port : ports) {
+			port.clearUncommitedData();
+		}
+		for(TestPortObject port : portsToAdd) {
+			port.clearUncommitedData();
+		}
+		
+		entriesToAdd.clear();
+		entriesToRemove.clear();
+		devicesToAdd.clear();
+		devicesToRemove.clear();
+		switchesToAdd.clear();
+		switchesToRemove.clear();
+		portsToAdd.clear();
+		portsToRemove.clear();
+	}
+	
+	
+	// this.*ForTest() methods below are supposed to be used for creation of test topology.
+	/**
+	 * Create new empty TestSwitchObject.
+	 * @return New TestSwitchObject
+	 */
+	public TestSwitchObject createNewSwitchForTest() {
+		TestSwitchObject sw = new TestSwitchObject();
+		switches.add(sw);
+		return sw;
+	}
+	
+	/**
+	 * Create new TestSwitchObject with specific DPID.
+	 * @param dpid DPID to be set
+	 * @return New TestSwitchObject
+	 */
+	public TestSwitchObject createNewSwitchForTest(String dpid) {
+		for(TestSwitchObject sw_loop : switches) {
+			if(sw_loop.getDPID().equals(dpid)) {
+				// Already created
+				log.error("switch already exists : " + dpid);
+				return sw_loop;
+			}
+		}
+
+		TestSwitchObject sw = new TestSwitchObject();
+		
+		sw.setDpidForTest(dpid);
+		switches.add(sw);
+		
+		return sw;
+	}
+	
+	/**
+	 * Create new empty TestPortObject.
+	 * @return New TestPortObject
+	 */
+	public TestPortObject createNewPortForTest() {
+		TestPortObject port = new TestPortObject();
+		ports.add(port);
+		return port;
+	}
+	
+	/**
+	 * Create new TestPortObject with specific DPID and port number.
+	 * @param dpid DPID to be set
+	 * @param number Port number to be set
+	 * @return New TestPortObject
+	 */
+	public TestPortObject createNewPortForTest(String dpid, Short number) {
+		TestSwitchObject sw = null;
+		
+		for(TestSwitchObject sw_loop : switches) {
+			if(sw_loop.getDPID().equals(dpid)) {
+				sw = sw_loop;
+			}
+		}
+		
+		if(sw != null) {
+			TestPortObject port = new TestPortObject();
+			port.setNumberForTest(number);
+			port.setSwitchForTest(sw);
+			sw.addPortForTest(port);
+			
+			ports.add(port);
+
+			return port;
+		} else {
+			return  null;
+		}
+	}
+	
+	/**
+	 * Link a TestPortObject to other TestPortObject.
+	 * @param src TestPortObjecgt of source port.
+	 * @param dst TestPortObjecgt of destination port.
+	 */
+	public void setLinkBetweenPortsForTest(TestPortObject src, TestPortObject dst) {
+		src.addLinkedPortForTest(dst);
+	}
+	
+	/**
+	 * Create new empty TestDeviceObject.
+	 * @return New TestDeviceObject
+	 */
+	public TestDeviceObject createNewDeviceForTest() {
+		TestDeviceObject dev = new TestDeviceObject();
+		
+		return dev;
+	}
+	
+	/**
+	 * Create new empty TestFlowPathObject.
+	 * @return New TestFlowPathObject
+	 */
+	public TestFlowPath createNewFlowPathForTest() {
+		TestFlowPath path = new TestFlowPath();
+		paths.add(path);
+		return path;
+	}
+
+	/**
+	 * Create new empty TestFlowEntryObject.
+	 * @return New TestFlowEntryObject
+	 */
+	public TestFlowEntry createNewFlowEntryForTest() {
+		TestFlowEntry entry = new TestFlowEntry();
+		entries.add(entry);
+		return entry;
+	}
+
+	
+	public boolean hasLinkBetween(String srcSw_str, Short srcNumber, String dstSw_str, Short dstNumber) {
+		IPortObject srcPort = null, dstPort = null;
+		long srcSw = HexString.toLong(srcSw_str);
+		long dstSw = HexString.toLong(dstSw_str);
+		
+		for(TestSwitchObject sw : switches) {
+			long swLong = HexString.toLong(sw.getDPID());
+			if(swLong == srcSw) {
+				for(IPortObject port : sw.getPorts()) {
+					if(port.getNumber().equals(srcNumber)) {
+						srcPort = port;
+					}
+				}
+			} else if(swLong == dstSw) {
+				for(IPortObject port : sw.getPorts()) {
+					if(port.getNumber().equals(dstNumber)) {
+						dstPort = port;
+					}
+				}
+			}
+		}
+		
+		if(srcPort != null && dstPort != null) {
+			for(IPortObject port : srcPort.getLinkedPorts()) {
+				if(port.equals(dstPort)) {
+					return true;
+				}
+			}
+		}
+		
+		return false;
+	}
+
+	// Overriding methods below are to mock GraphDBOperation class.
+	@Override
+	public ISwitchObject newSwitch(String dpid) {
+		TestSwitchObject sw = new TestSwitchObject();
+		sw.setDPID(dpid);
+		switchesToAdd.add(sw);
+		
+		return sw;
+	}
+
+	@Override
+	public ISwitchObject searchSwitch(String dpid_str) {
+		Long dpid = HexString.toLong(dpid_str);
+		
+		for(ISwitchObject sw : switches) {
+			if(HexString.toLong(sw.getDPID()) == dpid) {
+				return sw;
+			}
+		}
+		return null;
+	}
+
+	@Override
+	public ISwitchObject searchActiveSwitch(String dpid_str) {
+		Long dpid = HexString.toLong(dpid_str);
+
+		for(ISwitchObject sw : switches) {
+			if(HexString.toLong(sw.getDPID()) == dpid && sw.getState().equals("ACTIVE")) {
+				return sw;
+			}
+		}
+		return null;
+	}
+
+	@Override
+	public Iterable<ISwitchObject> getActiveSwitches() {
+		List<ISwitchObject> list = new ArrayList<ISwitchObject>();
+		
+		for(ISwitchObject sw : switches) {
+			if(sw.getState() != null && sw.getState().equals("ACTIVE")) {
+				list.add(sw);
+			}
+		}
+		return list.isEmpty() ? null : list;
+	}
+
+	@Override
+	public Iterable<ISwitchObject> getAllSwitches() {
+		List<ISwitchObject> list = new ArrayList<ISwitchObject>();
+		
+		for(ISwitchObject sw : switches) {
+			list.add(sw);
+		}
+		
+		return list.isEmpty() ? null : list;
+	}
+
+	@Override
+	public Iterable<ISwitchObject> getInactiveSwitches() {
+		List<ISwitchObject> list = new ArrayList<ISwitchObject>();
+		
+		for(ISwitchObject sw : switches) {
+			if(! sw.getState().equals("ACTIVE")) {
+				list.add(sw);
+			}
+		}
+		return list.isEmpty() ? null : list;
+	}
+
+	@Override
+	public Iterable<IFlowEntry> getAllSwitchNotUpdatedFlowEntries() {
+		List<IFlowEntry> list = new ArrayList<IFlowEntry>();
+		
+		for(TestFlowEntry entry : entries) {
+			if(entry.getSwitchState().equals("FE_SWITCH_NOT_UPDATED")) {
+				list.add(entry);
+			}
+		}
+		return list;
+	}
+
+	@Override
+	public void removeSwitch(ISwitchObject sw) {
+		if(switches.contains(sw)) {
+			switchesToRemove.add((TestSwitchObject)sw);
+		}
+	}
+
+	@Override
+	public IPortObject newPort(Short portNumber) {
+		TestPortObject port = new TestPortObject();
+		port.setNumber(portNumber);
+		
+		return port;
+	}
+
+	public IPortObject newPort(Long dpid, Short portNumber) {
+		TestPortObject port = null;
+		TestSwitchObject sw = (TestSwitchObject)searchSwitch(HexString.toHexString(dpid));
+		
+		if(sw != null) {
+			port = (TestPortObject)newPort(portNumber);
+			portsToAdd.add(port);
+			sw.addPort(port);
+		}
+		
+		return port;
+	}
+	
+	@Override
+	public IPortObject searchPort(String dpid_str, short number) {
+		long dpid = HexString.toLong(dpid_str);
+		
+		for(TestSwitchObject sw : switches) {
+			if(HexString.toLong(sw.getDPID()) == dpid) {
+				for(IPortObject port : sw.getPorts()) {
+					if(port.getNumber().equals(number)) {
+						return port;
+					}
+				}
+			}
+		}
+		return null;
+	}
+
+	@Override
+	public void removePort(IPortObject port) {
+		for(TestSwitchObject sw : switches) {
+			for(IPortObject pt : sw.getPorts()) {
+				if(pt.equals(port)) {
+					sw.removePort(port);
+				}
+			}
+		}
+		portsToRemove.add((TestPortObject)port);
+	}
+
+	@Override
+	public IDeviceObject newDevice() {
+		TestDeviceObject dev = new TestDeviceObject();
+		devicesToAdd.add(dev);
+		
+		return dev;
+	}
+
+	@Override
+	public IDeviceObject searchDevice(String macAddr) {
+		for(IDeviceObject dev : devices) {
+			if(dev.getMACAddress().equals(macAddr)) {
+				return dev;
+			}
+		}
+		return null;
+	}
+
+	@Override
+	public Iterable<IDeviceObject> getDevices() {
+		List<IDeviceObject> list = new ArrayList<IDeviceObject>();
+		
+		for(TestDeviceObject dev : devices) {
+			list.add(dev);
+		}
+		
+		return list;
+	}
+
+	@Override
+	public void removeDevice(IDeviceObject dev) {
+		if(devices.contains((TestDeviceObject)dev)) {
+			devicesToRemove.add((TestDeviceObject)dev);
+		}
+	}
+
+	@Override
+	public IFlowPath newFlowPath() {
+		TestFlowPath path = new TestFlowPath();
+		pathsToAdd.add(path);
+		
+		return path;
+	}
+
+	@Override
+	public IFlowPath searchFlowPath(FlowId flowId) {
+		for(IFlowPath path : paths) {
+			if(path.getFlowId().equals(flowId)) {
+				return path;
+			}
+		}
+		return null;
+	}
+
+	@Override
+	public IFlowPath getFlowPathByFlowEntry(IFlowEntry flowEntry) {
+		for(IFlowPath path : paths) {
+			for(IFlowEntry entry : path.getFlowEntries()) {
+				if(entry.equals(flowEntry)) {
+					return path;
+				}
+			}
+
+		}
+		return null;
+	}
+
+	@Override
+	public Iterable<IFlowPath> getAllFlowPaths() {
+		List<IFlowPath> list = new ArrayList<IFlowPath>();
+		
+		for(IFlowPath path : paths) {
+			list.add(path);
+		}
+		
+		return list;
+	}
+
+	@Override
+	public void removeFlowPath(IFlowPath flowPath) {
+		if(paths.contains((TestFlowPath)flowPath)) {
+			pathsToRemove.add((TestFlowPath)flowPath);
+		}
+	}
+
+	@Override
+	public IFlowEntry newFlowEntry() {
+		TestFlowEntry entry = new TestFlowEntry();
+		entriesToAdd.add(entry);
+		return entry;
+	}
+
+	@Override
+	public IFlowEntry searchFlowEntry(FlowEntryId flowEntryId) {
+		for(TestFlowEntry entry : entries) {
+			// TODO check if this matching works
+			if(entry.getFlowEntryId().equals(flowEntryId)) {
+				return entry;
+			}
+		}
+		return null;
+	}
+
+	@Override
+	public Iterable<IFlowEntry> getAllFlowEntries() {
+		List<IFlowEntry> list = new ArrayList<IFlowEntry>();
+		
+		for(TestFlowEntry entry : entries) {
+			list.add(entry);
+		}
+		
+		return list;
+	}
+
+	@Override
+	public void removeFlowEntry(IFlowEntry flowEntry) {
+		if(entries.contains((TestFlowEntry)flowEntry)) {
+			entriesToRemove.add((TestFlowEntry)flowEntry);
+		}
+	}
+
+	@Override
+	public IDBConnection getDBConnection() {
+		return super.getDBConnection();
+	}
+
+	@Override
+	public void commit() {
+		for(TestSwitchObject sw : switchesToAdd) {
+			switches.add(sw);
+		}
+		for(TestSwitchObject sw : switchesToRemove) {
+			sw.commit();
+			switches.remove(sw);
+		}
+		for(TestSwitchObject sw : switches) {
+			sw.commit();
+		}
+		
+		for(TestPortObject port : portsToAdd) {
+			ports.add(port);
+		}
+		for(TestPortObject port : portsToRemove) {
+			port.commit();
+			ports.remove(port);
+		}
+		for(TestPortObject port : ports) {
+			port.commit();
+		}
+		
+		for(TestDeviceObject dev : devicesToAdd) {
+			devices.add(dev);
+		}
+		for(TestDeviceObject dev : devicesToRemove) {
+			dev.commit();
+			devices.remove(dev);
+		}
+		for(TestDeviceObject dev : devices) {
+			dev.commit();
+		}
+		
+		clearUncommitedData();
+	}
+
+	@Override
+	public void rollback() {
+		clearUncommitedData();
+	}
+
+	@Override
+	public void close() {
+		// TODO Auto-generated method stub
+
+	}
+}