Building a choreography specification

  - Existing proposals: BPEL4WS/WSBPEL, BPML, BPSS, WSCI, WSCL
- Formal mathematical models: Petri nets, π-calculus, ambient
    calculus, ...
- How exhaustive and complete are the existing proposal? See Wil van der
    Aalst's workflow patterns work
- Is choreography enough?
    
      - Discovery: in a wide sense
- Security: crossing secure boundaries
- Reliability: need actions to happen
- ...