In every composite, messages are exchanged between participants. So far, we have only looked at simple interactions, that is, a single request followed by a reply, whether synchronous or asynchronous.
Asynchronous messaging adds additional complexities around the routing and correlation of replies. In this chapter, we look at how the SOA Service Infrastructure uses WS-Addressing to manage this, and in situations where this can't be used, examine how we can use correlation sets in BPEL to achieve the same result.
As a part of this, we look at some common, but more complex, messaging patterns and requirements such as: