Changing IoTRMIComm into abstract and refactoring into Client and Server parts
authorrtrimana <rtrimana@uci.edu>
Sat, 28 Jan 2017 00:56:06 +0000 (16:56 -0800)
committerrtrimana <rtrimana@uci.edu>
Sat, 28 Jan 2017 00:56:06 +0000 (16:56 -0800)
iotjava/iotrmi/Java/IoTRMIComm.java
iotjava/iotrmi/Java/IoTRMICommClient.java [new file with mode: 0644]
iotjava/iotrmi/Java/IoTRMICommServer.java [new file with mode: 0644]

index 0be3a250fa6bbcb3f82067d45ff11db91c51173d..685bcc53053ea7ab12e6fe88046196bfb7e6dd55 100644 (file)
@@ -14,7 +14,7 @@ import java.util.concurrent.*;
 import java.util.concurrent.atomic.AtomicBoolean;
 
 
-/** Class IoTRMIComm is a class that combines IoTRMIObject and IoTRMICall
+/** Abstract class IoTRMIComm is a class that combines IoTRMIObject and IoTRMICall
  *  <p>
  *  We will arbitrate packets into 2 queues and wake up the right threads/callers.
  *  We separate traffics one-directionally.
@@ -23,40 +23,29 @@ import java.util.concurrent.atomic.AtomicBoolean;
  * @version     1.0
  * @since       2017-01-27
  */
-public class IoTRMIComm {
+public abstract class IoTRMIComm {
 
        /**
         * Class Properties
         */
-       private List<String> listMethodId2Sign; // List of method signature (we use list index as method Id)
-       private IoTRMIUtil rmiUtil;
-       private IoTSocketServer rmiServerSend;
-       private IoTSocketServer rmiServerRecv;
-       private IoTSocketClient rmiClientSend;
-       private IoTSocketClient rmiClientRecv;
-       private byte[] methodBytes;
-       private byte[] retValueBytes;
-       private ConcurrentLinkedQueue<byte[]> methodQueue;
-       private ConcurrentLinkedQueue<byte[]> returnQueue;
-       private Map<Integer,AtomicBoolean> mapSkeletonId;
-       private Map<String,AtomicBoolean> mapStubId;
-       private AtomicBoolean didGetMethodBytes;
-       private AtomicBoolean didGetReturnBytes;
-       private AtomicBoolean didServerSendConnect;
-       private AtomicBoolean didServerRecvConnect;
-       private int objectIdCounter = Integer.MAX_VALUE;
+       protected IoTRMIUtil rmiUtil;
+       protected byte[] methodBytes;
+       protected byte[] retValueBytes;
+       protected ConcurrentLinkedQueue<byte[]> methodQueue;
+       protected ConcurrentLinkedQueue<byte[]> returnQueue;
+       protected Map<Integer,AtomicBoolean> mapSkeletonId;
+       protected Map<String,AtomicBoolean> mapStubId;
+       protected AtomicBoolean didGetMethodBytes;
+       protected AtomicBoolean didGetReturnBytes;
+       protected int objectIdCounter = Integer.MAX_VALUE;
 
        /**
         * Constructor (for skeleton)
         */
-       public IoTRMIComm(int _portSend, int _portRecv) throws  
+       public IoTRMIComm() throws  
                ClassNotFoundException, InstantiationException, 
                        IllegalAccessException, IOException {
 
-               didGetMethodBytes = new AtomicBoolean(false);
-               didGetReturnBytes = new AtomicBoolean(false);
-               didServerSendConnect = new AtomicBoolean(false);
-               didServerRecvConnect = new AtomicBoolean(false);
                rmiUtil = new IoTRMIUtil();
                methodBytes = null;
                retValueBytes = null;
@@ -64,163 +53,13 @@ public class IoTRMIComm {
                returnQueue = new ConcurrentLinkedQueue<byte[]>();
                mapSkeletonId = new HashMap<Integer,AtomicBoolean>();
                mapStubId = new HashMap<String,AtomicBoolean>();
-               //rmiServerSend = new IoTSocketServer(_portSend);
-               //rmiServerSend.connect();
-               //rmiServerRecv = new IoTSocketServer(_portRecv);
-               //rmiServerRecv.connect();
-               rmiServerSend = new IoTSocketServer(_portSend);
-               rmiServerRecv = new IoTSocketServer(_portRecv);
-               waitForConnectionOnServerSend();
-               waitForConnectionOnServerRecv();
-               while(!didServerSendConnect.get());     // Wait until server is connected
-               while(!didServerRecvConnect.get()); // Wait until server is connected
-               rmiClientSend = null;
-               rmiClientRecv = null;
-               waitForPacketsOnServer();
-               wakeUpThreadOnMethodCall();
-               wakeUpThreadOnReturnValue();
-       }
-
-
-       /**
-        * waitForConnectionOnServerSend() starts a thread that waits server connection
-        */
-       public void waitForConnectionOnServerSend() {
-
-               Thread thread = new Thread() {
-                       public void run() {
-                               try {
-                                       rmiServerSend.connect();
-                                       didServerSendConnect.set(true);
-                               } catch (Exception ex) {
-                                       ex.printStackTrace();
-                                       throw new Error("IoTRMIComm: Error receiving return value bytes on client!");
-                               }
-                       }
-               };
-               thread.start();
-       }
-
-
-       /**
-        * waitForConnectionOnServerRecv() starts a thread that waits server connection
-        */
-       public void waitForConnectionOnServerRecv() {
-
-               Thread thread = new Thread() {
-                       public void run() {
-                               try {
-                                       rmiServerRecv.connect();
-                                       didServerRecvConnect.set(true);
-                               } catch (Exception ex) {
-                                       ex.printStackTrace();
-                                       throw new Error("IoTRMIComm: Error receiving return value bytes on client!");
-                               }
-                       }
-               };
-               thread.start();
-       }
-
-
-       /**
-        * Constructor (for stub) - send and recv from the perspective of RMI socket servers
-        */
-       public IoTRMIComm(int _localPortSend, int _localPortRecv, int _portSend, int _portRecv, String _address, int _rev) throws  
-               ClassNotFoundException, InstantiationException, 
-                       IllegalAccessException, IOException {
-
                didGetMethodBytes = new AtomicBoolean(false);
                didGetReturnBytes = new AtomicBoolean(false);
-               didServerSendConnect = null;
-               didServerRecvConnect = null;
-               rmiUtil = new IoTRMIUtil();
-               methodBytes = null;
-               retValueBytes = null;
-               methodQueue = new ConcurrentLinkedQueue<byte[]>();
-               returnQueue = new ConcurrentLinkedQueue<byte[]>();
-               mapSkeletonId = new HashMap<Integer,AtomicBoolean>();
-               mapStubId = new HashMap<String,AtomicBoolean>();
-               rmiServerSend = null;
-               rmiServerRecv = null;
-               rmiClientRecv = new IoTSocketClient(_localPortSend, _portSend, _address, _rev);
-               rmiClientSend = new IoTSocketClient(_localPortRecv, _portRecv, _address, _rev);
-               waitForPacketsOnClient();
                wakeUpThreadOnMethodCall();
                wakeUpThreadOnReturnValue();
        }
 
 
-       /**
-        * waitForPacketsOnServer() starts a thread that waits for packet bytes on server side
-        */
-       public void waitForPacketsOnServer() {
-
-               Thread thread = new Thread() {
-                       public void run() {
-                               byte[] packetBytes = null;
-                               while(true) {
-                                       try {
-                                               packetBytes = rmiServerRecv.receiveBytes(packetBytes);
-                                               if (packetBytes != null) {
-                                                       System.out.println("Packet received: " + Arrays.toString(packetBytes));
-                                                       int packetType = IoTRMIComm.getPacketType(packetBytes);
-                                                       if (packetType == IoTRMIUtil.METHOD_TYPE) {
-                                                               System.out.println("Method packet: " + Arrays.toString(packetBytes));
-                                                               methodQueue.offer(packetBytes);
-                                                       } else if (packetType == IoTRMIUtil.RET_VAL_TYPE) {
-                                                               System.out.println("Return value packet: " + Arrays.toString(packetBytes));
-                                                               returnQueue.offer(packetBytes);
-                                                       } else
-                                                               throw new Error("IoTRMIComm: Packet type is unknown: " + packetType);
-                                               } //else
-                                               //      Thread.sleep(100);
-                                               packetBytes = null;
-                                       } catch (Exception ex) {
-                                               ex.printStackTrace();
-                                               throw new Error("IoTRMIComm: Error receiving return value bytes on client!");
-                                       }
-                               }
-                       }
-               };
-               thread.start();
-       }
-
-
-       /**
-        * waitForPacketsOnClient() starts a thread that waits for packet bytes on client side
-        */
-       public void waitForPacketsOnClient() {
-
-               Thread thread = new Thread() {
-                       public void run() {
-                               byte[] packetBytes = null;
-                               while(true) {
-                                       try {
-                                               packetBytes = rmiClientRecv.receiveBytes(packetBytes);
-                                               if (packetBytes != null) {
-                                                       int packetType = IoTRMIComm.getPacketType(packetBytes);
-                                                       if (packetType == IoTRMIUtil.METHOD_TYPE) {
-                                                               System.out.println("Method packet: " + Arrays.toString(packetBytes));
-                                                               methodQueue.offer(packetBytes);
-                                                       } else if (packetType == IoTRMIUtil.RET_VAL_TYPE) {
-                                                               System.out.println("Return value packet: " + Arrays.toString(packetBytes));
-                                                               returnQueue.offer(packetBytes);
-                                                       } else
-                                                               throw new Error("IoTRMIComm: Packet type is unknown: " + packetType);
-                                               } //else
-                                               //      Thread.sleep(100);
-                                               packetBytes = null;
-                                       } catch (Exception ex) {
-                                               ex.printStackTrace();
-                                               throw new Error("IoTRMIComm: Error receiving return value bytes on client!");
-                                       }
-                               }
-                       }
-               };
-               thread.start();
-       }
-
-
        /**
         * wakeUpThreadOnMethodCall() wakes up the correct thread when receiving method call
         */
@@ -442,52 +281,15 @@ public class IoTRMIComm {
 
 
        /**
-        * sendReturnObj() static version
+        * sendReturnObj() abstract version
         */
-       public synchronized void sendReturnObj(Object retObj, byte[] methodBytes) throws IOException {
-
-               // Send back return value
-               byte[] retObjBytes = IoTRMIUtil.getObjectBytes(retObj);
-               // Send return value together with OBJECT_ID and METHOD_ID for arbitration
-               int objMethIdLen = IoTRMIUtil.OBJECT_ID_LEN + IoTRMIUtil.METHOD_ID_LEN;
-               int headerLen = objMethIdLen + IoTRMIUtil.PACKET_TYPE_LEN;
-               byte[] retAllBytes = new byte[headerLen + retObjBytes.length];
-               // Copy OBJECT_ID and METHOD_ID
-               System.arraycopy(methodBytes, 0, retAllBytes, 0, objMethIdLen);
-               int packetType = IoTRMIUtil.RET_VAL_TYPE;       // This is a return value
-               byte[] packetTypeBytes = IoTRMIUtil.intToByteArray(packetType);
-               System.arraycopy(packetTypeBytes, 0, retAllBytes, objMethIdLen, IoTRMIUtil.PACKET_TYPE_LEN);
-               // Copy array of bytes (return object)
-               System.arraycopy(retObjBytes, 0, retAllBytes, headerLen, retObjBytes.length);
-               if (rmiServerSend == null)
-                       rmiClientSend.sendBytes(retAllBytes);
-               else
-                       rmiServerSend.sendBytes(retAllBytes);
-       }
+       public abstract void sendReturnObj(Object retObj, byte[] methodBytes);
 
 
        /**
-        * sendReturnObj() overloaded to send multiple return objects for structs
+        * sendReturnObj() abstract version
         */
-       public synchronized void sendReturnObj(Class<?>[] retCls, Object[] retObj, byte[] methodBytes) throws IOException {
-
-               // Send back return value
-               byte[] retObjBytes = returnToBytes(retCls, retObj);
-               // Send return value together with OBJECT_ID and METHOD_ID for arbitration
-               int objMethIdLen = IoTRMIUtil.OBJECT_ID_LEN + IoTRMIUtil.METHOD_ID_LEN;
-               int headerLen = objMethIdLen + IoTRMIUtil.PACKET_TYPE_LEN;
-               byte[] retAllBytes = new byte[headerLen + retObjBytes.length];
-               // Copy OBJECT_ID and METHOD_ID
-               System.arraycopy(methodBytes, 0, retAllBytes, 0, objMethIdLen);
-               int packetType = IoTRMIUtil.RET_VAL_TYPE;       // This is a return value
-               byte[] packetTypeBytes = IoTRMIUtil.intToByteArray(packetType);
-               System.arraycopy(packetTypeBytes, 0, retAllBytes, objMethIdLen, IoTRMIUtil.PACKET_TYPE_LEN);
-               // Copy array of bytes (return object)
-               if (rmiServerSend == null)
-                       rmiClientSend.sendBytes(retAllBytes);
-               else
-                       rmiServerSend.sendBytes(retAllBytes);
-       }
+       public abstract void sendReturnObj(Class<?>[] retCls, Object[] retObj, byte[] methodBytes);
 
 
        /**
@@ -532,22 +334,9 @@ public class IoTRMIComm {
 
 
        /**
-        * remoteCall() calls a method remotely by passing in parameters
+        * remoteCall() abstract version
         */
-       public synchronized void remoteCall(int objectId, int methodId, Class<?>[] paramCls, Object[] paramObj) {
-
-               // Send method info
-               byte[] methodBytes = methodToBytes(objectId, methodId, paramCls, paramObj);
-               try {
-                       if (rmiClientSend == null)
-                               rmiServerSend.sendBytes(methodBytes);
-                       else
-                               rmiClientSend.sendBytes(methodBytes);
-               } catch (IOException ex) {
-                       ex.printStackTrace();
-                       throw new Error("IoTRMICall: Error when sending bytes in remoteCall()!");
-               }
-       }
+       public abstract void remoteCall(int objectId, int methodId, Class<?>[] paramCls, Object[] paramObj);
 
 
        /**
diff --git a/iotjava/iotrmi/Java/IoTRMICommClient.java b/iotjava/iotrmi/Java/IoTRMICommClient.java
new file mode 100644 (file)
index 0000000..7b26445
--- /dev/null
@@ -0,0 +1,151 @@
+package iotrmi.Java;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.lang.reflect.*;
+
+import java.util.concurrent.*;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+
+/** Class IoTRMICommClient is a class that extends IoTRMIComm
+ *  <p>
+ *  This is a version of IoTRMIComm that sits on the main stub.
+ *
+ * @author      Rahmadi Trimananda <rtrimana @ uci.edu>
+ * @version     1.0
+ * @since       2017-01-27
+ */
+public class IoTRMICommClient extends IoTRMIComm {
+
+       /**
+        * Class Properties
+        */
+       private IoTSocketClient rmiClientSend;
+       private IoTSocketClient rmiClientRecv;
+       private int objectIdCounter = Integer.MAX_VALUE;
+
+
+       /**
+        * Constructor (for stub) - send and recv from the perspective of RMI socket servers
+        */
+       public IoTRMICommClient(int _localPortSend, int _localPortRecv, int _portSend, int _portRecv, String _address, int _rev) throws  
+               ClassNotFoundException, InstantiationException, 
+                       IllegalAccessException, IOException {
+
+               super();
+               rmiClientRecv = new IoTSocketClient(_localPortSend, _portSend, _address, _rev);
+               rmiClientSend = new IoTSocketClient(_localPortRecv, _portRecv, _address, _rev);
+               waitForPacketsOnClient();
+       }
+
+
+       /**
+        * waitForPacketsOnClient() starts a thread that waits for packet bytes on client side
+        */
+       public void waitForPacketsOnClient() {
+
+               Thread thread = new Thread() {
+                       public void run() {
+                               byte[] packetBytes = null;
+                               while(true) {
+                                       try {
+                                               packetBytes = rmiClientRecv.receiveBytes(packetBytes);
+                                               if (packetBytes != null) {
+                                                       int packetType = IoTRMIComm.getPacketType(packetBytes);
+                                                       if (packetType == IoTRMIUtil.METHOD_TYPE) {
+                                                               System.out.println("Method packet: " + Arrays.toString(packetBytes));
+                                                               methodQueue.offer(packetBytes);
+                                                       } else if (packetType == IoTRMIUtil.RET_VAL_TYPE) {
+                                                               System.out.println("Return value packet: " + Arrays.toString(packetBytes));
+                                                               returnQueue.offer(packetBytes);
+                                                       } else
+                                                               throw new Error("IoTRMIComm: Packet type is unknown: " + packetType);
+                                               } //else
+                                               //      Thread.sleep(100);
+                                               packetBytes = null;
+                                       } catch (Exception ex) {
+                                               ex.printStackTrace();
+                                               throw new Error("IoTRMIComm: Error receiving return value bytes on client!");
+                                       }
+                               }
+                       }
+               };
+               thread.start();
+       }
+
+
+       /**
+        * sendReturnObj() for non-struct objects (client side)
+        */
+       public synchronized void sendReturnObj(Object retObj, byte[] methodBytes) {
+
+               // Send back return value
+               byte[] retObjBytes = IoTRMIUtil.getObjectBytes(retObj);
+               // Send return value together with OBJECT_ID and METHOD_ID for arbitration
+               int objMethIdLen = IoTRMIUtil.OBJECT_ID_LEN + IoTRMIUtil.METHOD_ID_LEN;
+               int headerLen = objMethIdLen + IoTRMIUtil.PACKET_TYPE_LEN;
+               byte[] retAllBytes = new byte[headerLen + retObjBytes.length];
+               // Copy OBJECT_ID and METHOD_ID
+               System.arraycopy(methodBytes, 0, retAllBytes, 0, objMethIdLen);
+               int packetType = IoTRMIUtil.RET_VAL_TYPE;       // This is a return value
+               byte[] packetTypeBytes = IoTRMIUtil.intToByteArray(packetType);
+               System.arraycopy(packetTypeBytes, 0, retAllBytes, objMethIdLen, IoTRMIUtil.PACKET_TYPE_LEN);
+               // Copy array of bytes (return object)
+               System.arraycopy(retObjBytes, 0, retAllBytes, headerLen, retObjBytes.length);
+               try {
+                       rmiClientSend.sendBytes(retAllBytes);
+               } catch (IOException ex) {
+                       ex.printStackTrace();
+                       throw new Error("IoTRMICommClient: Error sending bytes in sendReturnObj()!");
+               }
+       }
+
+
+       /**
+        * sendReturnObj() overloaded to send multiple return objects for structs (client side)
+        */
+       public synchronized void sendReturnObj(Class<?>[] retCls, Object[] retObj, byte[] methodBytes) {
+
+               // Send back return value
+               byte[] retObjBytes = returnToBytes(retCls, retObj);
+               // Send return value together with OBJECT_ID and METHOD_ID for arbitration
+               int objMethIdLen = IoTRMIUtil.OBJECT_ID_LEN + IoTRMIUtil.METHOD_ID_LEN;
+               int headerLen = objMethIdLen + IoTRMIUtil.PACKET_TYPE_LEN;
+               byte[] retAllBytes = new byte[headerLen + retObjBytes.length];
+               // Copy OBJECT_ID and METHOD_ID
+               System.arraycopy(methodBytes, 0, retAllBytes, 0, objMethIdLen);
+               int packetType = IoTRMIUtil.RET_VAL_TYPE;       // This is a return value
+               byte[] packetTypeBytes = IoTRMIUtil.intToByteArray(packetType);
+               System.arraycopy(packetTypeBytes, 0, retAllBytes, objMethIdLen, IoTRMIUtil.PACKET_TYPE_LEN);
+               // Copy array of bytes (return object)
+               try {
+                       rmiClientSend.sendBytes(retAllBytes);
+               } catch (IOException ex) {
+                       ex.printStackTrace();
+                       throw new Error("IoTRMICommClient: Error sending bytes in sendReturnObj()!");
+               }
+       }
+
+
+       /**
+        * remoteCall() calls a method remotely by passing in parameters (client side)
+        */
+       public synchronized void remoteCall(int objectId, int methodId, Class<?>[] paramCls, Object[] paramObj) {
+
+               // Send method info
+               byte[] methodBytes = methodToBytes(objectId, methodId, paramCls, paramObj);
+               try {
+                       rmiClientSend.sendBytes(methodBytes);
+               } catch (IOException ex) {
+                       ex.printStackTrace();
+                       throw new Error("IoTRMICommClient: Error when sending bytes in remoteCall()!");
+               }
+       }
+}
diff --git a/iotjava/iotrmi/Java/IoTRMICommServer.java b/iotjava/iotrmi/Java/IoTRMICommServer.java
new file mode 100644 (file)
index 0000000..bf8d3b5
--- /dev/null
@@ -0,0 +1,200 @@
+package iotrmi.Java;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.lang.reflect.*;
+
+import java.util.concurrent.*;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+
+/** Class IoTRMICommServer is a class that extends IoTRMI
+ *  <p>
+ *  We will arbitrate packets into 2 queues and wake up the right threads/callers.
+ *  We separate traffics one-directionally.
+ *
+ * @author      Rahmadi Trimananda <rtrimana @ uci.edu>
+ * @version     1.0
+ * @since       2017-01-27
+ */
+public class IoTRMICommServer extends IoTRMIComm {
+
+       /**
+        * Class Properties
+        */
+       private IoTSocketServer rmiServerSend;
+       private IoTSocketServer rmiServerRecv;
+       private AtomicBoolean didServerSendConnect;
+       private AtomicBoolean didServerRecvConnect;
+       
+
+       /**
+        * Constructor (for skeleton)
+        */
+       public IoTRMICommServer(int _portSend, int _portRecv) throws  
+               ClassNotFoundException, InstantiationException, 
+                       IllegalAccessException, IOException {
+
+               super();
+               didServerSendConnect = new AtomicBoolean(false);
+               didServerRecvConnect = new AtomicBoolean(false);
+               rmiServerSend = new IoTSocketServer(_portSend);
+               rmiServerRecv = new IoTSocketServer(_portRecv);
+               waitForConnectionOnServerSend();
+               waitForConnectionOnServerRecv();
+               while(!didServerSendConnect.get());     // Wait until server is connected
+               while(!didServerRecvConnect.get()); // Wait until server is connected
+               waitForPacketsOnServer();
+       }
+
+
+       /**
+        * waitForConnectionOnServerRecv() starts a thread that waits server connection
+        */
+       public void waitForConnectionOnServerRecv() {
+
+               Thread thread = new Thread() {
+                       public void run() {
+                               try {
+                                       rmiServerRecv.connect();
+                                       didServerRecvConnect.set(true);
+                               } catch (Exception ex) {
+                                       ex.printStackTrace();
+                                       throw new Error("IoTRMIComm: Error receiving return value bytes on client!");
+                               }
+                       }
+               };
+               thread.start();
+       }
+
+
+       /**
+        * waitForConnectionOnServerSend() starts a thread that waits server connection
+        */
+       public void waitForConnectionOnServerSend() {
+
+               Thread thread = new Thread() {
+                       public void run() {
+                               try {
+                                       rmiServerSend.connect();
+                                       didServerSendConnect.set(true);
+                               } catch (Exception ex) {
+                                       ex.printStackTrace();
+                                       throw new Error("IoTRMIComm: Error receiving return value bytes on client!");
+                               }
+                       }
+               };
+               thread.start();
+       }
+
+
+       /**
+        * waitForPacketsOnServer() starts a thread that waits for packet bytes on server side
+        */
+       public void waitForPacketsOnServer() {
+
+               Thread thread = new Thread() {
+                       public void run() {
+                               byte[] packetBytes = null;
+                               while(true) {
+                                       try {
+                                               packetBytes = rmiServerRecv.receiveBytes(packetBytes);
+                                               if (packetBytes != null) {
+                                                       System.out.println("Packet received: " + Arrays.toString(packetBytes));
+                                                       int packetType = IoTRMIComm.getPacketType(packetBytes);
+                                                       if (packetType == IoTRMIUtil.METHOD_TYPE) {
+                                                               System.out.println("Method packet: " + Arrays.toString(packetBytes));
+                                                               methodQueue.offer(packetBytes);
+                                                       } else if (packetType == IoTRMIUtil.RET_VAL_TYPE) {
+                                                               System.out.println("Return value packet: " + Arrays.toString(packetBytes));
+                                                               returnQueue.offer(packetBytes);
+                                                       } else
+                                                               throw new Error("IoTRMIComm: Packet type is unknown: " + packetType);
+                                               } //else
+                                               //      Thread.sleep(100);
+                                               packetBytes = null;
+                                       } catch (Exception ex) {
+                                               ex.printStackTrace();
+                                               throw new Error("IoTRMIComm: Error receiving return value bytes on client!");
+                                       }
+                               }
+                       }
+               };
+               thread.start();
+       }
+
+
+       /**
+        * sendReturnObj() for non-struct objects (server side)
+        */
+       public synchronized void sendReturnObj(Object retObj, byte[] methodBytes) {
+
+               // Send back return value
+               byte[] retObjBytes = IoTRMIUtil.getObjectBytes(retObj);
+               // Send return value together with OBJECT_ID and METHOD_ID for arbitration
+               int objMethIdLen = IoTRMIUtil.OBJECT_ID_LEN + IoTRMIUtil.METHOD_ID_LEN;
+               int headerLen = objMethIdLen + IoTRMIUtil.PACKET_TYPE_LEN;
+               byte[] retAllBytes = new byte[headerLen + retObjBytes.length];
+               // Copy OBJECT_ID and METHOD_ID
+               System.arraycopy(methodBytes, 0, retAllBytes, 0, objMethIdLen);
+               int packetType = IoTRMIUtil.RET_VAL_TYPE;       // This is a return value
+               byte[] packetTypeBytes = IoTRMIUtil.intToByteArray(packetType);
+               System.arraycopy(packetTypeBytes, 0, retAllBytes, objMethIdLen, IoTRMIUtil.PACKET_TYPE_LEN);
+               // Copy array of bytes (return object)
+               System.arraycopy(retObjBytes, 0, retAllBytes, headerLen, retObjBytes.length);
+               try {
+                       rmiServerSend.sendBytes(retAllBytes);
+               } catch (IOException ex) {
+                       ex.printStackTrace();
+                       throw new Error("IoTRMICommServer: Error sending bytes in sendReturnObj()!");
+               }
+       }
+
+
+       /**
+        * sendReturnObj() overloaded to send multiple return objects for structs (server side)
+        */
+       public synchronized void sendReturnObj(Class<?>[] retCls, Object[] retObj, byte[] methodBytes) {
+
+               // Send back return value
+               byte[] retObjBytes = returnToBytes(retCls, retObj);
+               // Send return value together with OBJECT_ID and METHOD_ID for arbitration
+               int objMethIdLen = IoTRMIUtil.OBJECT_ID_LEN + IoTRMIUtil.METHOD_ID_LEN;
+               int headerLen = objMethIdLen + IoTRMIUtil.PACKET_TYPE_LEN;
+               byte[] retAllBytes = new byte[headerLen + retObjBytes.length];
+               // Copy OBJECT_ID and METHOD_ID
+               System.arraycopy(methodBytes, 0, retAllBytes, 0, objMethIdLen);
+               int packetType = IoTRMIUtil.RET_VAL_TYPE;       // This is a return value
+               byte[] packetTypeBytes = IoTRMIUtil.intToByteArray(packetType);
+               System.arraycopy(packetTypeBytes, 0, retAllBytes, objMethIdLen, IoTRMIUtil.PACKET_TYPE_LEN);
+               // Copy array of bytes (return object)
+               try {
+                       rmiServerSend.sendBytes(retAllBytes);
+               } catch (IOException ex) {
+                       ex.printStackTrace();
+                       throw new Error("IoTRMICommServer: Error sending bytes in sendReturnObj()!");
+               }
+       }
+
+
+       /**
+        * remoteCall() calls a method remotely by passing in parameters (server side)
+        */
+       public synchronized void remoteCall(int objectId, int methodId, Class<?>[] paramCls, Object[] paramObj) {
+
+               // Send method info
+               byte[] methodBytes = methodToBytes(objectId, methodId, paramCls, paramObj);
+               try {
+                       rmiServerSend.sendBytes(methodBytes);
+               } catch (IOException ex) {
+                       ex.printStackTrace();
+                       throw new Error("IoTRMICommServer: Error when sending bytes in remoteCall()!");
+               }
+       }
+}