1. π4π4 Dancing with Services 10th January 2005 Steve Ross-Talbot Pi4 Technologies

2. π4π4 Agenda Choreography WS-CDL Tools The future

3. π4π4 Choreography - the beginning Working Group formed January 2003 Initially tasked with defining business processes (aka BPML and BPEL) in a Web Service context Focus became a behavioral contract language for distributed systems

4. π4π4 Choreography - milestones Requirements document published in Invited experts (Milner, Honda, Yoshida) joined in Published first draft of WS-CDL in Published last call draft of WS-CDL in Published candidate recommendation draft of WS-CDL in Published working draft of WS-CDL primer in

5. π4π4 Choreography - today Primer likely to be published as a working note end Q1 2006 Formal underpinnings likely to be published as a working note Q22006 Implementations ….. –Pi4 Technologies (www.pi4soa.org)www.pi4soa.org –Imperial College –Trustcom –One other Users …. –3 vertical standards organisations –2 Banks –1 Telco

6. π4π4 WS-CDL An XML language for describing the behavioral contract of collections of peered services in order to achieve some goal Akin to UML sequence diagrams with no ambiguities and a robust behavioral type system

7. π4π4 WS-CDL - Structure

8. π4π4 WS-CDL - An example

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13. π4π4 WS-CDL - Structural clarity

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15. π4π4 WS-CDL - Can I dance? The dancers: Are the services in an SOA The dance steps: Are the interactions

16. π4π4 WS-CDL - Can I dance? Gateway svc asks Validation svc to validate trade

17. π4π4 WS-CDL - Can I dance? Validation svc asks RefData svc to lookup various components as part of validation

18. π4π4 WS-CDL - Can I dance? Once validation is complete Validation svc informs Gateway svc

19. π4π4 WS-CDL - Can I dance? Gateway svc asks Transaction svc to persist the validated trade

20. π4π4 WS-CDL - Can I dance? Transaction svc stores trade in Repository

21. π4π4 WS-CDL - Can I dance? Gateway svc asks Cashflow svc and Confirm svc to execute in parallel

22. π4π4 WS-CDL - Can I dance? Confirm svc communicates with various other svcs

23. π4π4 WS-CDL - Can I dance? RefData svc could have returned a fault to the Validation svc because a counterparty was invalid

24. π4π4 WS-CDL - Can I dance? As a result of a fault the Validation svc sends the Exception svc a message to alert someone of the problem.

25. π4π4 WS-CDL - Can I dance? Which may get fixed in-situ

26. π4π4 WS-CDL - Can I dance? And so validation is repeated

27. π4π4 WS-CDL - Can I dance? The Gateway svc is unaware that problems occurred and were fixed.

28. π4π4 WS-CDL - Can I dance? But the Exception svc might not be able to fix the problem. It sends a fault back to the Validation svc

29. π4π4 WS-CDL - Can I dance? Which enables an exception block in which a further message is sent from the Validation svc to the Exception svc to inform someone of a major problem.

30. π4π4 WS-CDL - Can I dance? And the conversation over the services is terminated

31. π4π4 WS-CDL - I cant dance because … GatewayValidationRefDataException Validation succeeds

32. π4π4 WS-CDL - I cant dance because … GatewayValidationRefDataException Validation succeeds after a fix

33. π4π4 WS-CDL - I cant dance because … GatewayValidationRefDataException Validation fails terminating the conversation The dance steps are incomplete. There are too many pages of instructions.

34. π4π4 WS-CDL - I can dance Gateway behaviour Validation behaviour RefData behaviour Exception behaviour

35. π4π4 WS-CDL - Tools Open Source www.pi4soa.org Eclipse pluginswww.pi4soa.org –Validating editor (graphical and tree based) –Behavioral Monitoring –CDL2Java (1.4, 1.5), CDL2BPEL (1.X, 2.0), CDL2WSDL (1.1, 2.0), CDL2EPP Project members –Steve Ross-Talbot, Gary Brown (lead), Nobuko Yoshida, Kohei Honda, Marco Carbone, Robin Milner, Charlton Barretto Custodian www.pi4tech.comwww.pi4tech.com –A new way to engage with academia –Royalty free –IP free

36. π4π4 WS-CDL - Tools Graphical Grammar

37. π4π4 WS-CDL - Tools Graphical Grammar

38. π4π4 WS-CDL - Tools Graphical Grammar

39. π4π4 WS-CDL - Tools Graphical Grammar

40. π4π4 WS-CDL - Tools Code Generation and Deployment

41. π4π4 WS-CDL - Tools Behavioral Monitor

42. π4π4 WS-CDL - The future Round tripping (Java2CDL and CDL2Java) Liveness properties Bisimulation (for conformance)

43. π4π4 The End