Wei Dong and Jan Newmarch June 2005 Session Management for Web Services by using SIP

2 Web Services Latest version of Client-Server computing Supported by major vendors Enormous amount of work being done Allows machine-to-machine interaction Replaces human-to-machine interaction

3 Technologies SOAP to carry messages WSDL to describe services UDDI to find services Many, many layers above this –WS-resources –WS-security –WS-reliable messaging –...

4 Session state SOAP is stateless There is no standard way of adding state There is no standard way to create –a shopping cart –user login and personalised interaction –a database transaction Just like the Web was in 1995

5 Adding session state Web documents use techniques such as –Cookies –URL rewriting –Hidden form fields These don't work for web services –No way of accessing HTTP cookies –No way of accessing URL information –No forms to hide fields in

6 Some ways to add state Add cookies to session headers (MicroSoft) –Not standard –Cookies have no semantic content WS-Resources (grid) –Not standard –Workaround by adding another heavy- weight layer

7 SIP Session Initiation Protocol IETF standard since 1999 Lightweight, simple, well-understood Used (and designed) for a variety of session management situations Not a “one-off” solution to a self-imposed problem

8 Using SIP within Web Services First, client opens a SIP session with a SIP session server, and gets a SIP session ID Client sends SIP session ID to Web Service on each call First time, Web Service joins session SIP server manages session –e.g. when client says “bye bye” to SIP server, server sends “bye bye” to web service

9 Implementation Added session management to Apache Axis server Demonstration built for Online Video Shopping Web Service

10 Transaction management Transactions involve techniques like 2- phase commit, supporting properties such as ACID Web Services have not standardised this –WS-Coordination –WS-Transaction Complex and still being developed

11 SIP Transaction Management We have built an ACID Transaction Manager as a Web Service A transaction is set up as a SIP session between the transaction manager and the transaction parties Demonstration of a bank transfer done

12 Conclusion Web Services have re-invented the wheel for many well-known concepts Current Web Service proposals are complex and still under development SIP is a well-known, standard and simple mechanism for session management We have shown that re-use of a known concept is better than re-invention of the concept We have shown that this can be easily used for transaction management as well