A SENS Internal Presentation on Friday, October 3, 2003 TRAP Transparent Reflective Aspect Programming SeyedMasoud Sadjadi Supervised by Dr. McKinley Software Engineering and Networking Systems Laboratory Department of Computer Science and Engineering Michigan State University

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 2 Acknowledgement  Dr. Cheng  Dr. Stirewalt  Eric Kasten  Zhenxiao Yang  Jesse Sowell  Zhinan Zhou  Farshad Samimi  Peng Ge

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 3 Agenda Motivation Running Example Architecture Implementation Related Work Architecture Running Example Motivation ImplementationOverview: Related Work Conclusion & Future Work Conclusion

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 4 Motivation  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 Architecture Running Example Motivation ImplementationOverview: Related Work Conclusion

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 5 Agenda Running Example Motivation Architecture Implementation Transparent Reflection Related Work Architecture Motivation Running Example ImplementationOverview: Related Work Conclusion & Future Work Conclusion

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 6 Interactive Video Multicast  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 Wired receivers Proxy Sender Wired receivers Access point Wireless receivers Architecture Motivation Running Example ImplementationOverview: Related Work Conclusion Ad-Hoc Network Hori. vs. Vertical Video Multicast

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 7 Ad-Hoc Network  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. Ad-Hoc Proxy1 SenderReceiver Wireless Ad-Hoc Network 11 Mbps Ethernet Ad-Hoc Proxy2 Low loss rate High loss rate Architecture Motivation Running Example ImplementationOverview: Related Work Conclusion Video Multicast Hori. vs. Vertical Ad-Hoc Network Low loss rate

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 8 Ad-Hoc Proxy 2 Domain-Specific Services Common Services Distribution Host-Infrastructure OS and Protocols Hardware Devices Horizontal vs. Vertical Adaptation  Horizontal Adaptation –Multi-Tier Adaptation  Vertical Adaptation –Multi-Layer (Cross-Layer) Adaptation Architecture Motivation Running Example ImplementationOverview: Related Work Conclusion Ad-Hoc Network Video Multicast Hori. vs. Vertical Middleware Layers Sender Domain-Specific Services Common Services Distribution Host-Infrastructure OS and Protocols Hardware Devices System Platform Ad-Hoc Proxy 1 Domain-Specific Services Common Services Distribution Host-Infrastructure OS and Protocols Hardware Devices Receiver Domain-Specific Services Common Services Distribution Host-Infrastructure OS and Protocols Hardware Devices Layers defined by Schmidt [2]

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 9 Agenda Architecture Motivation Running Example Implementation Related Work Running Example Motivation Architecture ImplementationOverview: Related Work Conclusion & Future Work Conclusion

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 10 A Simple Generic Ad-Hoc Proxy … public class relay { DatagramSocket rs; DatagramSocket ss; public void run() { … rs = new DatagramSocket(recv_port); ss = new DatagramSocket(); 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 Running Example Motivation Architecture ImplementationOverview: Related Work Conclusion Run-Time Model Layered Class Gr. Ad-Hoc Proxy

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 11 Run-Time Class Graph Model Running Example Motivation Architecture ImplementationOverview: Related Work Conclusion Ad-Hoc Proxy Layered Class Gr Run-Time Model … public class relay { DatagramSocket rs; DatagramSocket ss; public void run() { … DatagramSocket rs = new DatagramSocket( recv_port); DatagramSocket ss = new DatagramSocket(); while (!EndOfStream) { rs.receive(packet); … ss.send(packetToSend); } // end while … } … } // end relay relay class DatagraSocket class relay object rsss Class Library Heap Simplified Run-Time Class Graph

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 12 Layered Class Graph Running Example Motivation Architecture ImplementationOverview: Related Work Conclusion Ad-Hoc Proxy Run-Time Model Layered Class GrApplicationLevel BaseLevel MetaLevel DelegateLevel Class Library Heap DatagramSocketrelay rs & ss relay BaseLevel_DatagramSocket re & ss MetaLevel_DatagramSocket rs & ss Del 1 Del 2 Del 3 del 1 del 2 del 3

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 13 Agenda Implementation Motivation Running Example Architecture Related Work Running Example Motivation Implementation ArchitectureOverview: Related Work Conclusion & Future Work Conclusion

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 14 Compiling Steps Running Example Motivation Implementation ArchitectureOverview: Related Work Conclusion Admin. Consoles Delegate Class Gen. Aspect Base-Level Class Meta-Level Class Compiling Steps Generating Reflective Classes Generating Aspect BaseLevel_ DatagramSocket.java “java.net. DatagramSocket” MetaLevel_ DatagramSocket.java Absorbing_ DatagramSocket.aj relay.java Application Source in Java Files AspectJ Compiler (ajc) relay.class Executable Application Class Files

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 15 Generated Aspect Running Example Motivation Implementation ArchitectureOverview: Related Work Conclusion Admin. Consoles Delegate Class Compiling Steps Base-Level Class Meta-Level Class Gen. Aspect public aspect Absorbing_DatagramSocket { pointcut DatagramSocket() : call(java.net.DatagramSocket.new()) && …; java.net.DatagramSocket around() throws java.net.SocketException : DatagramSocket() { return new 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) { return new BaseLevel_DatagramSocket(p0); } … // Pointcuts and advices around the static public methods … // Pointcuts and advices around the final public mehtods pointcut getClass(BaseLevel_DatagramSocket targetObj) : …; }

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 16 Generated Base-Level Class Running Example Motivation Implementation ArchitectureOverview: Related Work Conclusion Admin. Consoles Delegate Class Gen. Aspect Compiling Steps Meta-Level Class Base-Level Class public class BaseLevel_DatagramSocket extends DatagramSocket implements BaseLevel_Interface { public BaseLevel_DatagramSocket() throws SocketException { super(); initMetaObject(); } public BaseLevel_DatagramSocket(int p0)throws SocketException { super(p0); initMetaObject(); } // Overriding the original methods. public void 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. public void Orig_send(java.net.DatagramPacket p0) throws IOException { super.send(p0); return; } }

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 17 Generated Meta-Level Class Running Example Motivation Implementation ArchitectureOverview: Related Work Conclusion Admin. Consoles Delegate Class Gen. Aspect Base-Level Class Compiling Steps Meta-Level Class public class MetaLevel_DatagramSocket extends UnicastRemoteObject implements MetaLevel_Interface, DelegateManagement { private Vector delegates = new Vector(); … public synchronized Object invokeMetaMethod(Method method, Object[] args, ChangeableBoolean isReplyReady) throws Throwable { if (isReplyReady.value) return null; if (delegates.size() == 0) throw new 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 throw new MetaMethodIsNotAvailable(method.toString()); else return newMethod.invoke(delegates.get(i-1), tempArgs); }

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 18 Administrative Consoles Running Example Motivation Implementation ArchitectureOverview: Related Work Conclusion Compiling Steps Delegate Class Gen. Aspect Base-Level Class Meta-Level Class Admin. Consoles

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 19 Delegate Class Running Example Motivation Implementation ArchitectureOverview: Related Work Conclusion Admin. Consoles Compiling Steps Gen. Aspect Base-Level Class Meta-Level Class Delegate Class public class Delegate_DatagramSocket_send extends UnicastRemoteObject implements Delegate_Interface, FilterManagement { private Vector filters = null; … public synchronized void send(DatagramPacket datagramPacket, ChangeableBoolean isReplyReady) throws IOException { if (isReplyReady.value) return; Packet packet = new Packet(0, new byte[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; }

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 20 Agenda Related Work Motivation Running Example Architecture Implementation Running Example Motivation Related Work Architecture ImplementationOverview: Conclusion & Future Work Conclusion

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 21 Related Work  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 Running Example Motivation Related Work Architecture ImplementationOverview: Conclusion

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 22 Conclusion  On-Demand Overhead  Selective Reflection  Transparent Adaptation  Legacy Application  Promoting Separation of Concerns Running Example Motivation Conclusion Architecture ImplementationOverview: Related Work Conclusion Related Work

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 23 Future Work  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 Running Example Motivation Conclusion Architecture ImplementationOverview: Related Work Conclusion

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 24 References [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 [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 [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 [4] Douglas C. Schmidt. Middleware for real-time and embedded systems. Communications of the ACM, 45(6), June Running Example Motivation Architecture ImplementationOverview: Conclusion Related Work

A SENS Presentation on Oct. e, 2003Transparent Reflection by S. M. Sadjadi 25 Questions? Thank you! Running Example Motivation Architecture ImplementationOverview: Conclusion Related Work