Ironically, a stateless ESB wouldn’t work well with Web Services-based SOA, because there is no broadly adopted standard way of putting state information in SOAP, and if you don’t store state information on the ESB, then you want to put it in the message. With REST, however, POST, PUT, and DELETE requests update resource state, and resources transfer application state to the client in representations in the form of hyperlinks. In other words, with REST we always transfer state in messages.

Read the entire post at http://www.devx.com/blog/looking-for-a-restful-soa-intermediary-part-two.html.