Design and Implementation of an Asynchronous Invocation Framework for Web Services

Asynchronous invocations are an important functionality in the context of distributed object frameworks, because in many situations clients should not block during remote invocations. There should be a loose coupling between clients and remote services. Popular web service frameworks, such as Apache Axis, offer only synchronous invocations (over HTTP). An alternative are messaging protocols but these implement a different communication paradigm. When client asynchrony is not supported, client developers have to build asynchronous invocations on top of the synchronous invocation facility. But this is tedious, error-prone, and might result in different remote invocation styles used within the same application. In this paper we build a framework using patterns for asynchronous invocation of web services. The framework design is based on the asynchrony patterns and other patterns from the same pattern language.