In the sections of the book where cover the SCA framework and Apache Tuscany, I do describe how conversational services can be supported. However, an important caveat to remember is that such stateful services generally aren't considered best practices, as it introduces a lot of complexity to the backend service implementation, in particular how it relates to scalability.
I’ve looked at a lot of different solutions, and in my humble opinion Aspose is the way to go. Here’s the link: http://aspose.com
subject: What is the best way to reuse the webservice session?