1. Disconnected

2. Introduction  XML based Web Services are becoming the norm on the Web  Mobile devices using these web service are becoming increasingly popular  Mobile Devices use networks that are characterized by frequent disconnections  Web Service need to be universally available  Need a solution that is transparently deployable and generally applicable

4. Caches  Caches meets the requirements of being transparent deployment and general applicable  Caches are not a new idea, but XML present a new set of challenges, due it vast set of operations and lack of involvement in caching  Solution is not complete !!!!

5. System put forward by our friends at Microsoft  Build the XML cache into a HTTP proxy to improve transparency  In disconnected mode, when a request is received return its cached responses.  If no response is cached, client timeouts and save the request in write back queue for later replay.  Good idea, but has some inherent flaws

7. Issues in caching XML for Web- Services  Caching XML web services does increase the availability of the service  However, the availability of the web service is limited due to several issues  Providing solutions to these issues will greatly increase the effectiveness and efficiency of the cache and thus the availability of the web service during periods of disconnection

8. Issues  Consistency  Understanding request and response messages  User Experience

9. Consistency  When operating in disconnected mode, strong consistency is not possible  But local (weak) consistency is  Providing weak consistency involves understanding the interdependencies between operation (difficult!)  GOAL: A smart cache manager that can invalidate and/or transform earlier requests

10. User XP  Ideally, users should have the same experience when disconnected as when they are connected High Availability Low Weak Consistency Strong Compromised User XP uncompromised

11. User XP: Cache Aware Clients  Adding optional attributes to SOAP messages for cache aware clients allowing them to react, notifying users of possible uncertainties…  These attributes can be ignored by cache unaware clients  Thus the systems remains Web- Service independent

12. Understanding SOAP Messages  Despite Std protocols, web service messages deviate considerably in structure  Using WSDL correctly formatted responses can be fabricated but not populated with default values  Therefore there is a need to extend the WSDL specs to allow the cache/proxy to be aware of the web-service semantics  This can be done without effecting current implementations of Web Services

13. Work Allocation  In essence, the core of the project determines to specify extensions to WSDL specifications  Darryl will focus on WSDL extensions which attempt to under the semantics of SOAP messages  Justin will focus on WSDL extensions which determine interdependencies of SOAP messages