TRAP Transparent Reflective Aspect Programming

1. TRAP Transparent Reflective Aspect Programming SeyedMasoud Sadjadi Supervised by Dr. McKinley http://www.cse.msu.edu/~{sadjadis,mckinley}/ Software Engineering and Networking Systems Laboratory Department of Computer Science and Engineering Michigan State University http://www.cse.msu.edu/sens/

2. Acknowledgement • Dr. Cheng • Dr. Stirewalt • Eric Kasten • Zhenxiao Yang • Jesse Sowell • Zhinan Zhou • Farshad Samimi • Peng Ge

3. Agenda Overview: Motivation Motivation Running Example Running Example Architecture Implementation Related Work Architecture Conclusion Implementation Related Work Conclusion & Future Work

4. Motivation Overview: • Separation of Concerns • Development • Maintenance • Dynamic adaptation • Selective Reflection • On demand overhead • Supporting Legacy Applications • Change of requirement • Adding Security • Change of execution environment • Wired to wireless • Dynamic Adaptation • Long running and critical applications (availability) • Promoting Assurance Analysis • A systematic (principled) approach to adaptation Motivation Running Example Architecture Implementation Related Work Conclusion

5. Agenda Overview: Motivation Motivation Running Example Running Example Architecture Implementation Related Work Architecture Conclusion Implementation Transparent Reflection Related Work Conclusion & Future Work

6. Wired receivers Wireless receivers Sender Access point Proxy Wired receivers Interactive Video Multicast Overview: • Interactive Video Multicast in Wireless LANs by Peng Ge • Proxy-based solution • The proxy serves a subgroup of wireless system • Extra processing power • Localize error correction Motivation Running Example Video Multicast Ad-Hoc Network Hori. vs. Vertical Architecture Implementation Related Work Conclusion

7. Ad-Hoc Network Overview: • Original Execution Environment • One hop wireless network using access point. • specified by Peng. • New Execution Environment • Multi-hop ad-hoc wireless network • Specified by Farshad. Motivation Running Example Video Multicast Ad-Hoc Network Hori. vs. Vertical Architecture Implementation Related Work Sender Wireless Ad-Hoc Network 11 Mbps Ethernet Receiver Conclusion Ad-Hoc Proxy1 Ad-Hoc Proxy2 Low loss rate Low loss rate High loss rate

8. Ad-Hoc Proxy 2 Receiver Ad-Hoc Proxy 1 Sender Domain-Specific Services Domain-Specific Services Domain-Specific Services Domain-Specific Services Common Services Common Services Common Services Common Services Distribution Distribution Distribution Distribution Host-Infrastructure Host-Infrastructure Host-Infrastructure Host-Infrastructure OS and Protocols OS and Protocols OS and Protocols OS and Protocols Hardware Devices Hardware Devices Hardware Devices Hardware Devices Horizontal vs. Vertical Adaptation Overview: • Horizontal Adaptation • Multi-Tier Adaptation • Vertical Adaptation • Multi-Layer (Cross-Layer) Adaptation Motivation Running Example Video Multicast Ad-Hoc Network Hori. vs. Vertical Architecture Implementation Related Work Conclusion Middleware Layers System Platform Layers defined by Schmidt [2]

9. Agenda Overview: Motivation Motivation Running Example Running Example Architecture Implementation Related Work Architecture Conclusion Implementation Related Work Conclusion & Future Work

10. … publicclass relay { DatagramSocket rs; DatagramSocket ss; publicvoid run() { … rs = newDatagramSocket(recv_port); ss = newDatagramSocket(); while (!EndOfStream) { rs.receive(packet); byte[] buf = Bytes.copy(packet.getData(), 0, packet.getLength()); DatagramPacket packetToSend = new DatagramPacket(buf, buf.length, target_address, target_port); ss.send(packetToSend); } // end while … } … } // end relay A Simple Generic Ad-Hoc Proxy Overview: Motivation Running Example Architecture Ad-Hoc Proxy Run-Time Model Layered Class Gr. Implementation Related Work Conclusion

11. Run-Time Class Graph Model Overview: … publicclass relay { DatagramSocket rs; DatagramSocket ss; publicvoid run() { … DatagramSocket rs = newDatagramSocket( recv_port); DatagramSocket ss = newDatagramSocket(); while (!EndOfStream) { rs.receive(packet); … ss.send(packetToSend); } // end while … } … } // end relay Simplified Run-Time Class Graph Motivation Running Example Architecture Heap Class Library Ad-Hoc Proxy Run-Time Model Layered Class Gr relay class relay object Implementation Related Work Conclusion DatagraSocket class rs ss

12. Layered Class Graph Overview: Motivation del 1 Del 1 Delegate Level del 3 Running Example Del 3 Del 2 del 2 Architecture Ad-Hoc Proxy Run-Time Model rs & ss MetaLevel_DatagramSocket Meta Level Layered Class Gr Implementation Related Work Conclusion re & ss BaseLevel_DatagramSocket Base Level rs & ss DatagramSocket relay relay Application Level Heap Class Library

13. Agenda Overview: Motivation Motivation Running Example Running Example Architecture Implementation Related Work Architecture Conclusion Implementation Related Work Conclusion & Future Work

14. relay .class Absorbing_ DatagramSocket .aj relay .java MetaLevel_ DatagramSocket .java BaseLevel_ DatagramSocket .java Compiling Steps Overview: Motivation Generating Reflective Classes Running Example “java.net. DatagramSocket” Architecture Generating Aspect Implementation Compiling Steps Gen. Aspect Base-Level Class Meta-Level Class Application Source in Java Files Admin. Consoles Delegate Class AspectJ Compiler (ajc) Related Work Conclusion Executable Application Class Files

15. Generated Aspect publicaspect Absorbing_DatagramSocket { pointcut DatagramSocket() : call(java.net.DatagramSocket.new()) && …; java.net.DatagramSocket around() throws java.net.SocketException : DatagramSocket() { returnnew BaseLevel_DatagramSocket(); } pointcut DatagramSocket_int(int p0) : call(java.net.DatagramSocket.new(int)) && args(p0) && …; java.net.DatagramSocket around(int p0) throws java.net.SocketException : DatagramSocket_int(p0) { returnnew BaseLevel_DatagramSocket(p0); } … // Pointcuts and advices around the static public methods … // Pointcuts and advices around the final public mehtods pointcut getClass(BaseLevel_DatagramSocket targetObj) : …; } Overview: Motivation Running Example Architecture Implementation Compiling Steps Gen. Aspect Base-Level Class Meta-Level Class Admin. Consoles Delegate Class Related Work Conclusion

16. Generated Base-Level Class Overview: publicclass BaseLevel_DatagramSocket extends DatagramSocket implements BaseLevel_Interface { publicBaseLevel_DatagramSocket() throws SocketException { super(); initMetaObject(); } publicBaseLevel_DatagramSocket(int p0)throws SocketException { super(p0); initMetaObject(); } // Overriding the original methods. publicvoid send(java.net.DatagramPacket p0) throws IOException { if(metaObject == null) { super.send(p0); return; } … Class[] paramType = new Class[1]; paramType[0] = java.net.DatagramPacket.class; Method method = BaseLevel_DatagramSocket.class.getDeclaredMethod( "send", paramType); ChangeableBoolean isReplyReady = new ChangeableBoolean(false); metaObject.invokeMetaMethod(method, tempArgs, isReplyReady); if(!isReplyReady.booleanValue()) super.send(p0); } // Original methods, but with "__Orig" appended to their names. publicvoidOrig_send(java.net.DatagramPacket p0) throws IOException { super.send(p0); return; } } Motivation Running Example Architecture Implementation Compiling Steps Gen. Aspect Base-Level Class Meta-Level Class Admin. Consoles Delegate Class Related Work Conclusion

17. Generated Meta-Level Class Overview: publicclass MetaLevel_DatagramSocket extends UnicastRemoteObject implements MetaLevel_Interface, DelegateManagement { private Vector delegates = new Vector(); … publicsynchronized Object invokeMetaMethod(Method method, Object[] args, ChangeableBoolean isReplyReady) throws Throwable { if (isReplyReady.value) returnnull; if (delegates.size() == 0) thrownew MetaMethodIsNotAvailable(method.toString()); Class[] paramType = method.getParameterTypes(); Class[] newParamType = new Class[paramType.length + 1]; for (int i = 0; i < paramType.length; i++) newParamType[i] = paramType[i]; newParamType[paramType.length] = ChangeableBoolean.class; Object[] tempArgs = new Object[args.length + 1]; for(int i=0; i<args.length; i++) tempArgs[i] = args[i]; tempArgs[args.length] = isReplyReady; … if(!delegateFound) // No meta-level method available thrownew MetaMethodIsNotAvailable(method.toString()); else return newMethod.invoke(delegates.get(i-1), tempArgs); } Motivation Running Example Architecture Implementation Compiling Steps Gen. Aspect Base-Level Class Meta-Level Class Admin. Consoles Delegate Class Related Work Conclusion

18. Administrative Consoles Overview: Motivation Running Example Architecture Implementation Compiling Steps Gen. Aspect Base-Level Class Meta-Level Class Admin. Consoles Delegate Class Related Work Conclusion

19. Delegate Class Overview: publicclass Delegate_DatagramSocket_send extends UnicastRemoteObject implements Delegate_Interface, FilterManagement { private Vector filters = null; … publicsynchronizedvoid send(DatagramPacket datagramPacket, ChangeableBoolean isReplyReady) throws IOException { if (isReplyReady.value) return; Packet packet = new Packet(0, newbyte[0], datagramPacket.getData()); Packet[] packetList = new Packet[1]; packetList[0] = packet; int filterCounter = 0; while (filterCounter < filters.size()) { Filter filter = (Filter)filters.get(filterCounter); try { packetList = filter.process(packetList); } catch (FilterMismatchException e) { EventMediator.instance().notify(new FilterMismatchEvent(this, e)); filterCounter--; } filterCounter++; } … isReplyReady.value = true; } } Motivation Running Example Architecture Implementation Compiling Steps Gen. Aspect Base-Level Class Meta-Level Class Admin. Consoles Delegate Class Related Work Conclusion

20. Agenda Overview: Motivation Motivation Running Example Running Example Architecture Implementation Related Work Architecture Conclusion Implementation Related Work Conclusion & Future Work

21. Related Work Overview: • Our Previous Work in SENS • Adaptive Java & MetaSockets • An Aspect-Oriented Approach to Dynamic Adaptation • SpartanJ • Other Work • Meta Java • Behavioral reflection • Java RMI • Iguana/J • Modifying the JVM • Reflective Java Motivation Running Example Architecture Implementation Related Work Conclusion

22. Conclusion Overview: • On-Demand Overhead • Selective Reflection • Transparent Adaptation • Legacy Application • Promoting Separation of Concerns Motivation Running Example Architecture Implementation Related Work Conclusion Conclusion Related Work

23. Future Work Overview: • Finishing Remaining Parts • Supporting fields • Test “static” • Test “final” • Applying to “Java RMI” • Dynamic Adaptation of Java Reflection • Toward Multi-Tier and Multi-Layer Adaptation Motivation Running Example Architecture Implementation Related Work Conclusion Conclusion Related Work

24. References Overview: [1] E. Kasten, P. K. McKinley, S. Sadjadi, and R. Stirewalt. Separating introspection and intercession in metamorphic distributed systems. In Proceedings of the IEEE Workshop on Aspect-Oriented Programming for Distributed Computing (with ICDCS'02), Vienna, Austia, July 2002. [2] Z. Yang, B. Cheng, R. Stirewalt, J. Sowell, S. Sadjadi, and P. McKinley. An aspect-oriented approach to dynamic adaptation. In Proceedings of Workshop On Self-healing Software, Nov. 2002. [3] S. M. Sadjadi, P. K. McKinley, and E. P. Kasten. Architecture and operation of an adaptable communication substrate. In The 9th International Workshop on Future Trends of Distributed Computing Systems (FTDCS '03), May 2003. [4] Douglas C. Schmidt. Middleware for real-time and embedded systems. Communications of the ACM, 45(6), June 2002. Motivation Running Example Architecture Implementation Related Work Conclusion

25. Overview: Questions? Motivation Running Example Architecture Implementation Related Work Conclusion Thank you!