Chapter 5. Conversations

While WSDL is a capable technology for describing the static aspects of a Web service's interface, it does little in the way of prescribing the ordering of its operations. For a Web service to be truly self-describing, it requires both static and interactive aspects of the interface to be understood by its consumers that is, how to "converse" with the service over successive invocations.

In the Web services arena, the first technology submitted to a standards body for describing the interactive behavioral aspects of a Web service is the Web Services Conversation Language (or WSCL). WSCL captures the conversation pattern that a Web service is expecting to engage in by describing the order in which its WSDL-described operations should be invoked.

In this chapter we explore the notion of a conversation and based on that experience, drill down into the features that WSCL provides. We demonstrate how WSCL constructs can be aggregated to build rich conversational patterns for Web service interactions. The chapter is drawn to a close with a discussion on how WSCL and WSDL can be used together to support truly automatic binding to Web services.