Caching of XML Web Services to Support Disconnected Operation

XML Web services can now be accessed in all places and at all times. The problem now facing these XML Web services is the need be to universal availability. Caching can be used by client applications that use XML Web Services on wireless or mobile networks in the face of intermittent connectivity. The idea of interjecting a client side cache proxy may be a step in the direction towards the ultimate goal of a seamless online/offline operating environment of these XML Web Services. But, Web services present new challenges to existing cache managers since they have generally been designed without regard to caching and hence offer little support. The WSDL description of a Web service specifies the message format of a necessary to invoke a service operation but lacks the information needed to indicate whether an operation will modify the server state or produce different results on different invocations. We have suggested several annotations to the WSDL document that will allow custom cache managers to tailor their behavior based on the specific requirements of the Web service. We then built a caching system onto an HTTP proxy and interjected it between a Web service and its application client, to test our assumptions. We demonstrated that a XML Web services could be operated to a limited extent disconnected from the server, without modifying the implementation of the service or their applications