Understanding Apache Axis2 Landscape and Architecture

1. Axis2 Landscape EranChinthaka School of Informatics and Computing Indiana University

2. Pre-Axis2 Era Axis2 – Diving in to Architecture How all projects fit together Q&A Agenda

3. About Me • Member, PMC Member and committer in Apache Software Foundation • PhD student in Indiana University, Bloomington, Indiana • Research on using usage patterns and knowledge-based techniques to improve job executions in large-scale systems (grids, clouds, etc)

4. Apache WS Timeline • Apache SOAP • Developed by IBM research team • Donated by IBM shortly after IBM joined the SOAP/WS initiative • Proof of concept • Apache Axis1 • SAX based • Handler architecture • Widely used in many products • WSS4J, Sandesha, Kandula, Pubscribe, WSRF support

5. Why Axis2 • Changes to Web service landscape mandated an extensible architecture • WS-Addressing , Reliable Messaging, WS-MEX • Performance • Parsers, message processing • Programming Abstractions • Asynchronous invocations, Message Exchange Patterns • Ease of use • Better APIs, Hot Deployment and other capabilities

6. Axis2 Features • High performance XML processing model • Extensible Messaging Engine • Rich Information Model • Pluggable module, data binding, transports architecture • Can support XMLBeans, ADB, JAXB, JiBX, etc., • Ability to plug-in any WS-* implementation • Easy to use deployment model • Convenient programming abstractions • WSDL 1.1, 2.0 and SOAP 1.1, 1.2 support • WSDL 2.0 HTTP binding, mimicing REST style invocations • Cloud computing support • Auto-scaling on Amazon • Clustering support

7. Axis2 Landscape • Community • Academic Usage • De-facto web services engine in research projects • Eucalyptus[1] • Industry Usage • Companies started consulting on Axis2 and/or building products on Axis2 • De-facto Web service engine for all the interoperability efforts [1]The Eucalyptus Open-source Cloud-computing System, Daniel Nurmi, Rich Wolski, Chris Grzegorczyk, GrazianoObertelli, Sunil Soman, Lamia Youseff, DmitriiZagorodnov, in Proceedings of 9th IEEE International Symposium on Cluster Computing and the Grid, Shanghai, China

8. Web services – Big Picture

9. Axis2 – SOAP Processing Model

10. Axis2 - Components Tools WSDL CodeGeneration Axis2 Engine Handlers Transports Information Model Deployment Model XML Model

11. XML Model • AXIOM (AXIs Object Model) • API is more like simplified DOM • Fundamental Difference • Data read and objects created on-demand using pull parsers • Allows direct access to the underlying pull stream with or without building the tree • Support for storing binary data • API also provides a StAX parser interface at any element • Allows the event based navigation of the OM tree.

12. Build object model to here h = envelope.getHeader(securityQName) ...and then you can do body = envelope.getBody(); reader = body.getXMLStreamReader(); while (reader.hasNext()) { ... } AXIOM Architecture- Deferred Building <soap:Envelope> <soap:Header> <myNS:Securitysoap:mustUnderstand=“true”> </myNS:Security> </soap:Header> <soap:Body> <doSomethingCool> ... MEGABYTES OF DATA HERE ... </doSomethingCool> </soap:Body> </soap:Envelope>

13. Phases, Modules, Handlers

14. Extensible Messaging Engine

15. Message Processing Stages • Transport Receivers • Dispatching • AddressingBasedDispatcher • RequestURIBasedDispatcher • SOAPActionBasedDispatcher • SOAPMessageBodyBasedDispatcher • User Handlers • Message Receivers

16. Dispatching ….. POST /axis2/services/EchoXMLService/echoOMElementHTTP/1.1 User-Agent: Axis2 Host: 127.0.0.1 Content-Type: application/soap+xml; charset=UTF-8;action="EchoOMElement"; ..................... <?xml version='1.0' encoding='UTF-8'?> <soapenv:Envelopexmlns:soapenv="http://www.w3.org/2003/05/soap-envelope" xmlns:wsa="http://www.w3.org/2005/08/addressing"> <soapenv:Header> <wsa:To>http://127.0.0.1:5556/axis2/services/EchoXMLService/echoOMElement</wsa:To> <wsa:ReplyTo> <wsa:Address>http://www.w3.org/2005/08/addressing/anonymous</wsa:Address> </wsa:ReplyTo> <wsa:MessageID>urn:uuid:AD147449058471C81E11506120248601</wsa:MessageID> <wsa:Action>urn:EchoOMElement</wsa:Action> </soapenv:Header> <soapenv:Body> <ns1:echoOMElement xmlns:ns1="http://org.apache.axis2/xsd"> <ns1:myValue>Isaac Asimov, The Foundation Trilogy</ns1:myValue> </ns1:echoOMElement> </soapenv:Body> </soapenv:Envelope>

17. Message Receiver • The last handler of the execution chain • MEP dependent (MEP ?? ) • Does the actual business logic invocation • Ability to write custom Message Receivers • Injects dependencies to services • Default Message Receivers • RawXMLINOnlyMessageReceiver • RawXMLINOutMessageReceiver • RPC*MessageReceiver

18. Message Exchange Patterns - MEP • Describes the exchange pattern of SOAP messages per given operation • In-Out • In only • In optional out

19. Information Model

20. Deployment Model • Axis 1.x deployment requires you to • modify the XML files or • Call the admin client, add to the classpath, restart the server • Archive based deployment • Bundle all together and drop in • Directory based deployment (similar structure as archive ) • Hot Deployment • Archive file can contain • Class files, third party libraries, any other resources required by the service

21. Deployment Model – Axis2 Service • Can be deployed as an archive (.aar) file or as a directory with all necessary resources • Isolated – separate Class loader

22. Deployment Model – Axis2 Service • Service configurations are given by the services.xml • No need to have a WSDL around to be a valid service !!! • Contains • Exposed transports • Service scopes • Action mappings and message receivers • Modules to be engaged

23. Deployment Model – Axis2 Module <module name="addressing"> <Description></Description> <InFlow> <handler name="AddressingFinalInHandler" class="org.apache.axis2.handlers.addressing.AddressingFinalInHandler"> <order phase="PreDispatch"/> </handler> .............. </InFlow> <OutFlow> <handler name="AddressingOutHandle” class="org.apache.axis2.handlers.addressing.AddressingOutHandler"> <order phase="MessageOut"/> </handler> </OutFlow> <OutFaultFlow> ............. </OutFaultFlow> <InFaultFlow> ............. </InFaultFlow> </module>

24. Client Interaction API • Supports both blocking and non-blocking invocations models • Concept of callbacks for the client for non- blocking case • handle both transport dependent and transport independent asynchrony • sendRobust • fireAndForget • sendReceive • sendReceiveNonBlocking

25. Code Generation • Generates Java/C and other language stubs from given WSDL files • for invoking a Web service • Stub, callback handler, data bound classes, build file • For authoring a Web service • Skeleton, custom message receiver, services.xml

26. How WS Projects Fit Together • Apache Axis2 Java/C implementations • WS-Commons • Axiom – the XML object model • XmlSchema – Xml schema model used within code generation, WSDL models • Transports • Neethi – WS-Policy implementation • Modules • Sandesha – WS-Reliable Messaging implementation • Rampart, Rahas – WS-Security, WS-Secureconversation, WS-Security Policy, WS-Trust implementations • Savan– WS-Eventing implementation • WS-Addressing • WSS4j – Web services security implementation including XML security • Woden – WSDL 2.0 object model

27. Resources • Latest Information • http://ws.apache.org/axis2 • Feedback, bugs, questions • axis-user@ws.apache.org, axis-dev@ws.apache.org

28. What’s Next? • Axis2 in the real world • Axis2 hands on • Axis2 Security

29. Thank You !! • All committers and users who contributed to make Axis2 the best open source Web service engine • Special thanks to DeepalJayasinghe for sharing his slides • Data-to-insight lab for making this talk possible

30. Questions !!