Section 3.1. Family Tree

3.1. Family Tree

Pi-calculus and the Petri net (or some combination of the two) provide the theoretical underpinnings for most of the major BPM standards. Four of the major contemporary standards betray pi-calculus influence:

• WS-CDL

• WSCI

• BPML

• XLANG

Three other major standards derive from the Petri net:

• BPMN

• YAWL

• WSFL

Finally, BPEL is a blend, inheriting traits of pi and Petri from its parent languages XLANG and WSFL, respectively. Figure 3-1 illustrates these relationships.

Figure 3-1. Theory family tree for BPM standards

In Figure 3-1, boxes represent standards, circles theories, and arrows dependencies. The level of dependency is extremely variable. Petri, for example, is woven into the fabric of YAWL, whereas BPMN and WSFL seem to merely draw inspiration from it. Pi's connection to each of its children is inspiration at best and mere hype at worst.