diff --git a/src/main/java/net/floodlightcontroller/devicemanager/internal/DeviceStorageImpl.java b/src/main/java/net/floodlightcontroller/devicemanager/internal/DeviceStorageImpl.java
index e964b8e..748d4ab 100644
--- a/src/main/java/net/floodlightcontroller/devicemanager/internal/DeviceStorageImpl.java
+++ b/src/main/java/net/floodlightcontroller/devicemanager/internal/DeviceStorageImpl.java
@@ -14,16 +14,16 @@
 import net.floodlightcontroller.devicemanager.IDeviceStorage;
 import net.floodlightcontroller.devicemanager.SwitchPort;
 import net.onrc.onos.util.GraphDBConnection;
-import net.onrc.onos.util.GraphDBConnection.Transaction;
+import net.onrc.onos.util.GraphDBOperation;
 
 public class DeviceStorageImpl implements IDeviceStorage {
 	
-	public GraphDBConnection conn;
+	public GraphDBOperation op;
 	protected static Logger log = LoggerFactory.getLogger(SwitchStorageImpl.class);
 
 	@Override
 	public void init(String conf) {
-		conn = GraphDBConnection.getInstance(conf);
+		op = new GraphDBOperation(GraphDBConnection.getInstance(conf));
 	}	
 
 	public void finalize() {		
@@ -32,7 +32,7 @@
 	
 	@Override
 	public void close() {
-		conn.close();
+		op.close();
 	}
 
 	@Override
@@ -40,24 +40,23 @@
 		// TODO Auto-generated method stub
 		IDeviceObject obj = null;
  		try {
-            if ((obj = conn.utils().searchDevice(conn, device.getMACAddressString())) != null) {
+            if ((obj = op.searchDevice(device.getMACAddressString())) != null) {
                 log.debug("Adding device {}: found existing device",device.getMACAddressString());
             } else {
-            	obj = conn.utils().newDevice(conn);
+            	obj = op.newDevice();
                 log.debug("Adding device {}: creating new device",device.getMACAddressString());
             }
             changeDeviceAttachments(device, obj);
             
  			obj.setIPAddress(device.getIPv4Addresses().toString());
  			obj.setMACAddress(device.getMACAddressString());
- 			obj.setType("device");
  			obj.setState("ACTIVE");
- 			conn.endTx(Transaction.COMMIT);
+ 			op.commit();
  			
  			log.debug("Adding device {}",device.getMACAddressString());
 		} catch (Exception e) {
             // TODO: handle exceptions
-          	conn.endTx(Transaction.ROLLBACK);
+          	op.rollback();
 			log.error(":addDevice mac:{} failed", device.getMACAddressString());
 		}	
 		
@@ -74,21 +73,21 @@
 		// TODO Auto-generated method stub
 		IDeviceObject dev;
 		try {
-			if ((dev = conn.utils().searchDevice(conn, device.getMACAddressString())) != null) {
-             	conn.utils().removeDevice(conn, dev);
-              	conn.endTx(Transaction.COMMIT);
+			if ((dev = op.searchDevice(device.getMACAddressString())) != null) {
+             	op.removeDevice(dev);
+              	op.commit();
             	log.error("DeviceStorage:removeDevice mac:{} done", device.getMACAddressString());
             }
 		} catch (Exception e) {
              // TODO: handle exceptions
-          	conn.endTx(Transaction.ROLLBACK);
+          	op.rollback();
 			log.error("DeviceStorage:removeDevice mac:{} failed", device.getMACAddressString());
 		}
 	}
 
 	@Override
 	public IDeviceObject getDeviceByMac(String mac) {
-		return conn.utils().searchDevice(conn, mac);
+		return op.searchDevice(mac);
 	}
 
 	@Override
@@ -102,17 +101,17 @@
 		// TODO Auto-generated method stub
 		IDeviceObject obj = null;
  		try {
-            if ((obj = conn.utils().searchDevice(conn, device.getMACAddressString())) != null) {
+            if ((obj = op.searchDevice(device.getMACAddressString())) != null) {
                 log.debug("Changing device ports {}: found existing device",device.getMACAddressString());
                 changeDeviceAttachments(device, obj);
-     			conn.endTx(Transaction.COMMIT);
+     			op.commit();
            } else {
    				log.debug("failed to search device...now adding {}",device.getMACAddressString());
    				addDevice(device);
            }            			
 		} catch (Exception e) {
             // TODO: handle exceptions
-          	conn.endTx(Transaction.ROLLBACK);
+          	op.rollback();
 			log.error(":addDevice mac:{} failed", device.getMACAddressString());
 		}	
 	}
@@ -122,9 +121,9 @@
 		List<IPortObject> attachedPorts = Lists.newArrayList(obj.getAttachedPorts());
 
         for (SwitchPort ap : attachmentPoints) {
-       	 IPortObject port = conn.utils().searchPort(conn,
-       			 									HexString.toHexString(ap.getSwitchDPID()),
-       												(short) ap.getPort());
+       	 IPortObject port = op.searchPort(
+       			 HexString.toHexString(ap.getSwitchDPID()),
+       			 (short) ap.getPort());
        	if (attachedPorts.contains(port)) {
        		attachedPorts.remove(port);
        	} else {
@@ -144,15 +143,15 @@
 		// TODO Auto-generated method stub
 		IDeviceObject obj;
   		try {
-  			if ((obj = conn.utils().searchDevice(conn, device.getMACAddressString())) != null) {
+  			if ((obj = op.searchDevice(device.getMACAddressString())) != null) {
             	obj.setIPAddress(device.getIPv4Addresses().toString());
-              	conn.endTx(Transaction.COMMIT); 
+              	op.commit(); 
   			} else {
             	log.error(":changeDeviceIPv4Address mac:{} failed", device.getMACAddressString());
              }		
   		} catch (TitanException e) {
             // TODO: handle exceptions
-          	conn.endTx(Transaction.ROLLBACK);
+          	op.rollback();
 			log.error(":changeDeviceIPv4Address mac:{} failed due to exception {}", device.getMACAddressString(),e);
 		}
 	}