diff --git a/src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkStorageImpl.java b/src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkStorageImpl.java
index 015514e..2a4c2b9 100644
--- a/src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkStorageImpl.java
+++ b/src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkStorageImpl.java
@@ -84,55 +84,13 @@
             	}
 
             	if (currLinks.contains(vportDst)) {
+            		// TODO: update linkinfo
             		if (op.equals(DM_OPERATION.INSERT) || op.equals(DM_OPERATION.CREATE)) {
             			log.debug("addOrUpdateLink(): failed link exists {} {} src {} dst {}", 
             					new Object[]{op, lt, vportSrc, vportDst});
-            		} else if (op.equals(DM_OPERATION.UPDATE)) {
-                		// TODO: update linkinfo
-            			// GraphDB seems to have no KeyIndex for LinkInfo data
-            			
-            			// BEGIN: trial code (update implementation)
-            			if(linkinfo != null) {
-            				vportSrc.setPortState(linkinfo.getSrcPortState());
-            				vportDst.setPortState(linkinfo.getDstPortState());
-            				
-            				Vertex vsrc = vportSrc.asVertex();
-    						vsrc.setProperty("first_seen_time", linkinfo.getFirstSeenTime());
-    						vsrc.setProperty("last_lldp_received_time", linkinfo.getUnicastValidTime());
-    						vsrc.setProperty("last_bddp_received_time", linkinfo.getMulticastValidTime());
-
-//            				for(Edge e: vportSrc.asVertex().getEdges(Direction.OUT)) {
-//            					if(e.getVertex(Direction.OUT).equals(vportDst.asVertex())) {
-//            						e.setProperty("first_seen_time", linkinfo.getFirstSeenTime());
-//            						e.setProperty("last_lldp_received_time", linkinfo.getUnicastValidTime());
-//            						e.setProperty("last_bddp_received_time", linkinfo.getMulticastValidTime());
-//            					}
-//            				}
-            				
-                    		conn.endTx(Transaction.COMMIT);
-                    		log.debug("addOrUpdateLink(): link updated {} {} src {} dst {}", new Object[]{op, lt, vportSrc, vportDst});
-            			}
-            			// END: trial code
             		}
             	} else {
-            		if (op.equals(DM_OPERATION.UPDATE)) {
-            			log.debug("addOrUpdateLink(): failed link doesn't exist {} {} src {} dst {}", 
-            					new Object[]{op, lt, vportSrc, vportDst});
-            		} else {
-                		vportSrc.setLinkPort(vportDst);
-                		
-            			// BEGIN: trial code (update implementation)
-            			if(linkinfo != null) {
-            				vportSrc.setPortState(linkinfo.getSrcPortState());
-            				vportDst.setPortState(linkinfo.getDstPortState());
-            				
-            				Vertex vsrc = vportSrc.asVertex();
-    						vsrc.setProperty("first_seen_time", linkinfo.getFirstSeenTime());
-    						vsrc.setProperty("last_lldp_received_time", linkinfo.getUnicastValidTime());
-    						vsrc.setProperty("last_bddp_received_time", linkinfo.getMulticastValidTime());
-            			}
-            			// END: trial code
-            		}
+            		vportSrc.setLinkPort(vportDst);
 
             		conn.endTx(Transaction.COMMIT);
             		log.debug("updateLink(): link added {} {} src {} dst {}", new Object[]{op, lt, vportSrc, vportDst});
@@ -191,13 +149,6 @@
          		}*/
          		vportSrc.removeLink(vportDst);
          		
-    			// BEGIN: trial code (update implementation)
-         		Vertex vsrc = vportSrc.asVertex();
-         		vsrc.removeProperty("first_seen_time");
-         		vsrc.removeProperty("last_lldp_received_time");
-         		vsrc.removeProperty("last_bddp_received_time");
-         		// END: trial code
-         		
         		conn.endTx(Transaction.COMMIT);
             	log.debug("deleteLink(): deleted edges src {} dst {}", new Object[]{
             			lt, vportSrc, vportDst});
@@ -264,19 +215,23 @@
 		}
 	}
 
+	// TODO: Fix me
 	@Override
 	public List<Link> getLinks(String dpid) {
 		GraphDBConnection conn = GraphDBConnection.getInstance(this.conf);
 		ISwitchObject vswitch;
 		List<Link> links = new ArrayList<Link>();
 
+		// BEGIN: Trial code
+		// author: Naoki Shiota
 		vswitch = conn.utils().searchSwitch(conn, dpid);
 
 		for(IPortObject vportSrc : vswitch.getPorts()) {
-			// TODO array concatenation may be heavy
+			// array concatenation may be heavy...
 			List<Link> sublinks = getLinks(HexString.toLong(dpid), vportSrc.getNumber());
 			links.addAll(sublinks);
 		}
+		// END: Trial code
 
 		return links;
 	}
diff --git a/src/main/java/net/onrc/onos/util/GraphDBConnection.java b/src/main/java/net/onrc/onos/util/GraphDBConnection.java
index 7041329..478763c 100644
--- a/src/main/java/net/onrc/onos/util/GraphDBConnection.java
+++ b/src/main/java/net/onrc/onos/util/GraphDBConnection.java
@@ -7,7 +7,6 @@
 
 import com.thinkaurelius.titan.core.TitanFactory;
 import com.thinkaurelius.titan.core.TitanGraph;
-import com.tinkerpop.blueprints.Edge;
 import com.tinkerpop.blueprints.TransactionalGraph;
 import com.tinkerpop.blueprints.Vertex;
 import com.tinkerpop.blueprints.util.wrappers.event.EventTransactionalGraph;
@@ -73,43 +72,6 @@
 						     Vertex.class);
 		        }
 		        
-		        // BEGIN: trial code
-		        /*
-		         * Trial to store link state information as properties of port.
-		         * Currently no need to be implemented. Just reference.
-		         */
-		        // These keys are assigned to port vertex with "OUT" direction link
-//		        if (!s_vertices.contains("first_seen_time")) {
-//		        	graph.createKeyIndex("first_seen_time", Vertex.class);
-//		        }
-//		        if (!s_vertices.contains("last_lldp_received_time")) {
-//		        	graph.createKeyIndex("last_lldp_received_time", Vertex.class);
-//		        }
-//		        if (!s_vertices.contains("last_bddp_received_time")) {
-//		        	graph.createKeyIndex("last_bddp_received_time", Vertex.class);
-//		        }
-//		        
-//		        
-//		        Set<String> s_edges = graph.getIndexedKeys(Edge.class);
-//		        if (!s_edges.contains("src_port_state")) {
-//		        	graph.createKeyIndex("src_port_state",
-//						     Edge.class);
-//		        }
-//		        if (!s_edges.contains("dst_port_state")) {
-//		        	graph.createKeyIndex("dst_port_state",
-//						     Edge.class);
-//		        }
-//		        if (!s_edges.contains("first_seen_time")) {
-//		        	graph.createKeyIndex("first_seen_time", Edge.class);
-//		        }
-//		        if (!s_edges.contains("last_lldp_received_time")) {
-//		        	graph.createKeyIndex("last_lldp_received_time", Edge.class);
-//		        }
-//		        if (!s_edges.contains("last_bddp_received_time")) {
-//		        	graph.createKeyIndex("last_bddp_received_time", Edge.class);
-//		        }
-		        // END: trial code
-		        
 		        graph.commit();
 		        eg = new EventTransactionalGraph<TitanGraph>(graph);
 		   }		   
diff --git a/src/test/java/net/floodlightcontroller/linkdiscovery/internal/LinkStorageImplTest.java b/src/test/java/net/floodlightcontroller/linkdiscovery/internal/LinkStorageImplTest.java
index 39221ab..6f62f76 100644
--- a/src/test/java/net/floodlightcontroller/linkdiscovery/internal/LinkStorageImplTest.java
+++ b/src/test/java/net/floodlightcontroller/linkdiscovery/internal/LinkStorageImplTest.java
@@ -85,6 +85,9 @@
 	}
 	
 	// 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();
@@ -97,6 +100,9 @@
 		doTestLinkHasStateOf(linkToUpdate, infoToVerify);
 	}
 	
+	/**
+	 * Test if update() can correctly creates a Link.
+	 */
 	@Test
 	public void testUpdate_CreateSingleLink() {
 		Link linkToCreate = createFeasibleLink();
@@ -114,6 +120,9 @@
 		doTestLinkIsInGraph(linkToVerify);
 	}
 
+	/**
+	 * Test if update() can correctly inserts a Link.
+	 */
 	@Test
 	public void testUpdate_InsertSingleLink(){
 		Link linkToInsert = createFeasibleLink();
@@ -132,6 +141,9 @@
 		doTestLinkIsInGraph(linkToVerify);
 	}
 	
+	/**
+	 * Test if update() can correctly deletes a Link.
+	 */
 	@Test
 	public void testUpdate_DeleteSingleLink(){
 		Link linkToDelete = createExistingLink();
@@ -148,7 +160,10 @@
 		linkStorage.update(linkToDelete, DM_OPERATION.DELETE);
 		doTestLinkIsNotInGraph(linkToVerify);
 	}
-		
+
+	/**
+	 * Test if update() can correctly creates multiple Links.
+	 */
 	@Test
 	public void testUpdate_CreateLinks(){
 		List<Link> linksToCreate = createFeasibleLinks();
@@ -168,6 +183,9 @@
 		}
 	}
 	
+	/**
+	 * Test if update() can handle mixture of normal/abnormal input for creation of Links.
+	 */
 	@Test
 	public void testUpdate_CreateLinks_Mixuture(){
 		List<Link> linksToCreate = new ArrayList<Link>();
@@ -180,6 +198,9 @@
 		doTestLinkIsInGraph(createExistingLink());
 	}
 
+	/**
+	 * Test if update() can correctly inserts multiple Links.
+	 */
 	@Test
 	public void testUpdate_InsertLinks(){
 		List<Link> linksToInsert = createFeasibleLinks();
@@ -199,6 +220,9 @@
 		}
 	}
 	
+	/**
+	 * Test if update() can handle mixture of normal/abnormal input for creation of Links.
+	 */
 	@Test
 	public void testUpdate_InsertLinks_Mixuture(){
 		List<Link> linksToInsert = new ArrayList<Link>();
@@ -211,7 +235,9 @@
 		doTestLinkIsInGraph(createExistingLink());
 	}
 
-
+	/**
+	 * Test if update() can correctly deletes multiple Links.
+	 */
 	@Test
 	public void testUpdate_DeleteLinks(){
 		List<Link> linksToDelete = createExistingLinks();
@@ -231,6 +257,9 @@
 		}
 	}
 	
+	/**
+	 * Test if update() can handle mixture of normal/abnormal input for deletion of Links.
+	 */
 	@Test
 	public void testUpdate_DeleteLinks_Mixuture(){
 		List<Link> linksToDelete = new ArrayList<Link>();
@@ -244,71 +273,86 @@
 	}
 	
 	// TODO: remove @Ignore after UPDATE method is implemented
+	/**
+	 * Test if updateLink() can correctly updates LinkInfo for a Link.
+	 */
 	@Ignore @Test
-	public void testAddOrUpdateLink_Update() {
+	public void testUpdateLink_Update() {
 		Link linkToUpdate= createExistingLink();
 		long currentTime = System.currentTimeMillis();
 		LinkInfo infoToUpdate = createFeasibleLinkInfo(currentTime);
 		LinkInfo infoToVerify = createFeasibleLinkInfo(currentTime);
 
-		linkStorage.addOrUpdateLink(linkToUpdate, infoToUpdate, ILinkStorage.DM_OPERATION.UPDATE);
+		linkStorage.updateLink(linkToUpdate, infoToUpdate, ILinkStorage.DM_OPERATION.UPDATE);
 		
 		doTestLinkHasStateOf(linkToUpdate, infoToVerify);
 	}
 	
+	/**
+	 * Test if updateLink() can correctly creates a Link.
+	 */
 	@Test
-	public void testAddOrUpdateLink_Create() {
+	public void testUpdateLink_Create() {
 		Link linkToCreate = createFeasibleLink();
 		Link linkToVerify = createFeasibleLink();
 		
 		//Use the link storage API to add the link
-		linkStorage.addOrUpdateLink(linkToCreate, null, ILinkStorage.DM_OPERATION.CREATE);
+		linkStorage.updateLink(linkToCreate, null, ILinkStorage.DM_OPERATION.CREATE);
 		doTestLinkIsInGraph(linkToVerify);
 
 		// Add same link
 		Link linkToCreateTwice = createFeasibleLink();
-		linkStorage.addOrUpdateLink(linkToCreateTwice, null, ILinkStorage.DM_OPERATION.CREATE);
+		linkStorage.updateLink(linkToCreateTwice, null, ILinkStorage.DM_OPERATION.CREATE);
 		
 		// this occurs assertion failure if there are two links in titanGraph
 		doTestLinkIsInGraph(linkToVerify);
 	}
 	
+	/**
+	 * Test if updateLink() can correctly inserts a Link.
+	 */
 	@Test
-	public void testAddOrUpdateLink_Insert() {
+	public void testUpdateLink_Insert() {
 		Link linkToInsert = createFeasibleLink();
 		Link linkToVerify = createFeasibleLink();
 		
 		//Use the link storage API to add the link
-		linkStorage.addOrUpdateLink(linkToInsert, null, ILinkStorage.DM_OPERATION.INSERT);
+		linkStorage.updateLink(linkToInsert, null, ILinkStorage.DM_OPERATION.INSERT);
 
 		doTestLinkIsInGraph(linkToVerify);
 		
 		// Add same link
 		Link linkToInsertTwice = createFeasibleLink();
-		linkStorage.addOrUpdateLink(linkToInsertTwice, null, ILinkStorage.DM_OPERATION.INSERT);
+		linkStorage.updateLink(linkToInsertTwice, null, ILinkStorage.DM_OPERATION.INSERT);
 
 		// this occurs assertion failure if there are two links in titanGraph
 		doTestLinkIsInGraph(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 testAddOrUpdateLink_Delete() {
+	public void testUpdateLink_Delete() {
 		Link linkToDelete = createExistingLink();
 		Link linkToVerify = createExistingLink();
 
 		// Test deletion of existing link
-		linkStorage.addOrUpdateLink(linkToDelete, null, DM_OPERATION.DELETE);
+		linkStorage.updateLink(linkToDelete, null, DM_OPERATION.DELETE);
 		doTestLinkIsNotInGraph(linkToVerify);
 		
 		linkToDelete = createFeasibleLink();
 		linkToVerify = createFeasibleLink();
 
 		// Test deletion of not-existing link
-		linkStorage.addOrUpdateLink(linkToDelete, null, DM_OPERATION.DELETE);
+		linkStorage.updateLink(linkToDelete, null, DM_OPERATION.DELETE);
 		doTestLinkIsNotInGraph(linkToVerify);
 	}
 	
+	/**
+	 * Test if getLinks() can correctly return Links connected to specific DPID and port.
+	 */
 	@Test
 	public void testGetLinks_ByDpidPort(){
 		Link linkToVerify = createExistingLink();
@@ -332,6 +376,9 @@
 		assertEquals(list2.size(), 0);
 	}
 	
+	/**
+	 * Test if getLinks() can correctly return Links connected to specific MAC address.
+	 */
 	@Test
 	public void testGetLinks_ByString() {
 		Link linkToVeryfy = createExistingLink();
@@ -344,6 +391,9 @@
 		assertFalse(links.contains(linkToVerifyNot));
 	}
 	
+	/**
+	 * Test if deleteLink() can correctly delete a Link.
+	 */
 	@Test
 	public void testDeleteLink() {
 		// Deletion of existing link
@@ -361,6 +411,9 @@
 		doTestLinkIsNotInGraph(linkToVerify);
 	}
 	
+	/**
+	 * Test if deleteLinks() can correctly delete Links.
+	 */
 	@Test
 	public void testDeleteLinks(){
 		List<Link> linksToDelete = createExistingLinks();
@@ -372,6 +425,9 @@
 		}
 	}
 	
+	/**
+	 * Test if deleteLinks() can handle mixture of normal/abnormal input.
+	 */
 	@Test
 	public void testDeleteLinks_Mixture(){
 		List<Link> linksToDelete = new ArrayList<Link>();
@@ -384,6 +440,9 @@
 		doTestLinkIsNotInGraph(createExistingLink());
 	}
 
+	/**
+	 * Test if getActiveLinks() can correctly return active Links.
+	 */
 	@Test
 	public void testGetActiveLinks() {
 		Link existingLink = createExistingLink();
@@ -395,6 +454,9 @@
 		assertFalse(links.contains(notExistingLink));
 	}
 	
+	/**
+	 * Test if deleteLinksOnPort() can delete Links.
+	 */
 	@Test
 	public void testDeleteLinksOnPort() {
 		Link linkToDelete = createExistingLink();
@@ -501,21 +563,7 @@
 		assertFalse(pipe.hasNext());
 
 		// TODO: implement test code to check if update is correctly done.
-		int portStateSrc = edge.getVertex(Direction.OUT).getProperty("port_state");
-		int portStateDst = edge.getVertex(Direction.IN).getProperty("port_state");
-		
-		assertTrue(portStateSrc == info.getSrcPortState());
-		assertTrue(portStateDst == info.getDstPortState());
-
-//		long firstSeenTime = edge.getProperty("first_seen_time");
-//		long lastLldpReceivedTime = edge.getProperty("last_lldp_received_time");
-//		long lastBddpReceivedTime = edge.getProperty("last_bddp_received_time");
-		long firstSeenTime = edge.getVertex(Direction.OUT).getProperty("first_seen_time");
-		long lastLldpReceivedTime = edge.getVertex(Direction.OUT).getProperty("last_lldp_received_time");
-		long lastBddpReceivedTime = edge.getVertex(Direction.OUT).getProperty("last_bddp_received_time");
-		assertTrue(firstSeenTime == info.getFirstSeenTime());		
-		assertTrue(lastLldpReceivedTime == info.getUnicastValidTime());
-		assertTrue(lastBddpReceivedTime == info.getMulticastValidTime());
+		assertTrue(false);
 	}