If SOA is indeed process-oriented (and this book's central argument is that it is), then good SOA requires the design of good SOA processes. One of the main challenges to process design is to deal effectively with complexity. Contrary to what most observers think, process complexity is not strictly a BPM concern; it's a myth that process people do BPM and SOA people excel only at moving packets through pipes. For some use cases, the end-to-end process is as likely to be managed in the SOA layer as in the BPM layer, as we discovered in Chapter 3. SOA processes can be long-running (as you may recall from Chapter 5) and orchestrate intricate sequences of partner interactions (as discussed in Chapter 4). Some of the largest processes in the enterprise are SOA processes.

As a process is arranged as a graph (that is, a network of boxes and arrows), the challenge is to avoid building a graph that is excessively deep and expansive. In general, the number of boxes is...