Over the years business processes have become automated to the point that the BPM community now considers the SOA language BPEL, designed for the orchestration of Web Services, as the best platform for building contemporary processes. But many processes retain some level of human activity, and BPEL's support for human interaction is problematic. Most attempts to integrate human workflow with BPEL, such as BPEL4People (as well as proprietary task subsystems offered by the major BPM vendors), try to fit human activities into BPEL's execution model. Human tasks are simply special steps in the larger process.
But people don't work that way, argues Keith Harrison-Broninski in his book Human Interactions: The Heart and Soul of Business Process Management. Their work is complex and ad hoc; they interleave their tasks and adapt how they work as business rules change. Harrison-Broninski proposes Role Activity Diagrams (RAD) as the best way to model human workflow, and dismisses BPEL as an impossible fit.
