Essential Business Process Modeling

Summary

The main points of this chapter include:

• Theory matters in BPM more than it does in most practical software fields. Theoreticians and practitioners tend to ignore each other’s work, but in BPM, practitioners are keenly interested in—and indeed, actively hype—academic conceptions such as the pi-calculus, the Petri net, and, to a lesser extent, the state machine.

• The pi-calculus, developed by Scottish mathematician Robin Milner in the 1990s, is an algebraic system for building processes that communicate with each other on channels. Each process has a control flow that supports sequential, conditional, or concurrent control flow.

• Pi-calculus processes are written as sets of equations using a particular syntax. The examples developed in this chapter capture the most common elements.

• According to pi-calculus convention, when one process sends information to another, it includes the name of the channel to be used for the other process to respond. This name is variable; it can change in response to changing conditions. Channel change is referred to as mobility.

• The pi-calculus is thought to be an underpinning of process languages XLANG, BPML, WSCI, and WS-CDL, though leading BPM commentator van der Aalst thinks the connection is mostly hype.

• The classical Petri net was developed by the mathematician Carl Adam Petri in the 1960s. A Petri net is a process; its main constructs are places (stopping points in the process, but NOT states), transitions (events that drive process movement), ...