TRAP/J: Transparent Grid Enablement using By Luis Atencio & Tatiana Soldo

1. TRAP/J Transparent Grid Enablement using By Luis Atencio & Tatiana Soldo

2. Sources • Sadjadi, Masoud S., McKinley, Phillip K., Cheng, Betty H.C., Stirewalt, Kurt.: TRAP/J: Transparent Generations of Adaptable Java Programs. • Sadjadi, Masoud S.: TRAP: Transparent Reflective Aspect Programming. (presentation) • Yang, Z., Cheng, Betty H.C., Stirewalt, R.E.K., Sowell, J., Sadjadi, MasoudS., McKinley, P.K.: An Aspect-Oriented Approach to Dynamic Adaptation.

3. Main Topics • Motivation • Background Information • Current Progress • Plans for the future

4. Motivation • Adaptability • Many distributed applications being ported to mobile computing environments were not designed to adapt to changing conditions. • Provide adaptability to component failures for longing and critical applications. • Separation of concerns • Functional Decomposition: separate the business logic from program logic. • Support for legacy code • There is no attempt to modify existing code

5. Main Topics • Motivation • Background Information • Current Progress • Plans for the future

6. BackgroundInformation • Behavioral Reflection and RMI • Aspect-Oriented Programming • Transparent Grid enablement T R A P / J

7. Behavioral Reflection • Reflection: • A technique that allows a program to perform a self examination of itself and its software environment . • Behavioral reflection: the ability of an application to alter its behavior

8. Aspect-Oriented Programming • Common Uses: • Debugging • Tracing • Aspect = Advice + Pointcut • Types of Advice: • Before • After • Around

9. Java RMI • Java API for RPC • RPC: remote method invocation: This allows a programmer to call procedures on another computer to be executed seamlessly as though the procedure resided locally on the computer. • Methods are accessed via an “rmi registry” which stores remote method object references.

10. Main Topics • Motivation • Background Information • Current Progress • Plans for the future

11. Working Example: ASA RECEIVER SENDER RECEIVER WIRELESS NETWORK RECEIVER AUDIO STREAM PATH

12. Absorbing_ MulticastSocket .aj Microphone .java Microphone .class Java.net. MulticastSocket MetaLevel_ MulticastSocket .java BaseLevel_ MulticastSocket .java Architecture: Compile-time Model TRAP/J Generating Reflective Classes Generating Aspect Class Name List Application Source in Java Files AspectJ Compiler (ajc) Adapt-Ready Application

13. Architecture: Runtime Model del 1 Del 1 Delegate Level del 3 Del 3 Del 2 del 2 ms MetaLevel_MulticastSocket Meta Level ms BaseLevel_MulticastSocket Base Level ms MulticastSocket Mic mic Application Level Heap Class Library

14. Diagram Application Layer public class Microphone { //private fields private MulticastSocket ms; private AudioRecorder audioRecorder; private DatagramPacket packetToSend; public void Run() { . . . multicastSocket = new MulticastSocket(); audioRecorder = new AudioRecorder(); . . . while(audioRecorder.read(packetRead, 0, packetRead.length) ! = -1) { packetToSend = new DatagramPacket(packetRead, packetReadf.length, target_adress, target_port); multicastSocket.send(packetToSend); } // end while . . . Heap Class Library Microphone class Mic object Java.net.MulticastSocket class ms Code: ASA developed by Dr. Sadjadi

15. Diagram Base-Level Layer CONSTRUCTOR // Generated Base Level Class CONSTRUCTOR public class BaseLevel_MulticastSocket extends MulticastSocket implements BaseLevel_Interface { private MetaLevel_Interface metaObject; public BaseLevel_MulticastSocket()throws java.io.IOException { super(); initMetaObject(); // creates instance of MetaLevel_MulticastSocket // passes this base level object as a parameter, // initializes metaObject. } Code: ASA developed by Dr. Sadjadi

16. Base-Level Layer SEND METHOD public void send(java.net.DatagramPacket p0)throws java.io.IOException { if(metaObject == null) { super.send(p0); return; } . . . Class[] paramType = new Class[1]; paramType[0] = java.net.DatagramPacket.class; Method method = null; method = BaseLevel_MulticastSocket.class.getMethod("send", paramType); Object[] tempArgs = new Object[1]; tempArgs[0] = p0; ChangeableBoolean isReplyReady = new ChangeableBoolean(false); try { metaObject.invokeMetaMethod(method, tempArgs, isReplyReady); } catch (MetaMethodIsNotAvailable e) . . . Code: ASA developed by Dr. Sadjadi

17. Diagram Meta-Level Layer public class MetaLevel_MulticastSocket extends UnicastRemoteObject implements MetaLevel_Interface,DelegateManagement { private BaseLevel_Interface baseObject; private Vector<Delegate_Interface> delegates = new Vector<Delegate_Interface>(); public MetaLevel_MulticastSocket(BaseLevel_MulticastSocket baseObject) throws RemoteException { super(); // reference to baseObject is initialized this.baseObject = baseObject; String name = GlobalConfig.instance().getAppName() + "_MetaLevel_MulticastSocket_" + counter++; // Bind this object instance to the name and store in RMI registry Naming.rebind(name, this); Vector<Integer> delegateLocations = new Vector<Integer>(0); Vector<String> delegateNames = new Vector<String>(0); // checks whether any delegates were implemented by //composer for this particular metaObject name if(Config.instance().check4DefaultDelagetes(name, delegateLocations, delegateNames)) { // if delegates were found they are stored in delegates vector for (int i = 0; i < delegateNames.size(); i++) { int loc = ((delegateLocations.get(i))).intValue(); String delegateName = delegateNames.get(i); insertDelegate(loc, delegateName); Code: ASA developed by Dr. Sadjadi

18. Meta-Level Layer public synchronized Object invokeMetaMethod(Method method,Object[] args, ChangeableBoolean isReplyReady) throws Throwable { . . . if (delegates.size() == 0) throw new MetaMethodIsNotAvailable(method.toString()); Method newMethod = null; . . . int i = 0; boolean delegateFound = true; do { delegateFound = true; try { newMethod = delegates.get(i).getClass().getDeclaredMethod(method.getName(), newParamType); } catch (NoSuchMethodException e) { delegateFound = false; } i++; // if a delegate is found, delegatefound will not be set to false and we jump out of the loop } while((i < delegates.size()) && !delegateFound); if(!delegateFound) // No meta-level method available for specifications given throw new MetaMethodIsNotAvailable(method.toString()); else // if delegatefound = true return newMethod.invoke(delegates.get(i-1), tempArgs); // invokes newMethod method on delegates.get(i-1) object with tempArgs as parameters Code: ASA developed by Dr. Sadjadi

19. Diagram Generated Aspects // Generated Aspect public aspect Absorbing_MulticastSocket_aj { // Pointcuts and advices around the public constructors pointcut MulticastSocket() :call(java.net.MulticastSocket.new()) && !within(edu.msu.cse.sens.reflect.generated..*); java.net.MulticastSocket around() throws java.io.IOException : MulticastSocket() { System.out.println("Aspects are present!"); System.out.flush(); return new BaseLevel_MulticastSocket(); } // Pointcuts and advices around static public and final public methods . . . } Code: ASA developed by Dr. Sadjadi

20. Main Topics • Motivation • Background Information • Current Progress • Plans for the future

21. Plans for the future • Currently: pervasive or ubiquitous • Grid Programming: Investigates techniques and tools to simplify the process of grid enablement • Autonomic Computing

22. Proposal To grid-enable existing applications transparently using TRAP/J. Goal: Design a simple test application and make it adaptable to a Grid environment. Expected Output: methodologies and tools that enable easy implementation of Grid Applications

23. The End