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Choreography, Orchestration, and Contracts Languages and Techniques for Service Composition

www.sensoria-ist.eu. Choreography, Orchestration, and Contracts Languages and Techniques for Service Composition. Gianluigi Zavattaro http://cs.unibo.it/~zavattar. Department of Computer Science University of Bologna.

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Choreography, Orchestration, and Contracts Languages and Techniques for Service Composition

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  1. www.sensoria-ist.eu Choreography, Orchestration, and ContractsLanguages and Techniques for Service Composition Gianluigi Zavattarohttp://cs.unibo.it/~zavattar Department of Computer ScienceUniversity of Bologna Based on joint work with: Mario Bravetti, Claudio Guidi, Ivan Lanese, Fabrizio Montesi

  2. Plan of the Talk Plan of the Talk • An “open” world of services • Service composition • Orchestration (bottom-up) • Choreography (top-down) • Contract-based service discovery • Output persistence • Strong Compliance • Message Queues • Conclusion and future work

  3. Plan of the Talk Plan of the Talk • An “open” world of services • Service composition • Orchestration (bottom-up) • Choreography (top-down) • Contract-based service discovery • Output persistence • Strong Compliance • Message Queues • Conclusion and future work

  4. An “open” world of services • Service Oriented Computing is used to design systems working in a heterogeneous and open environment where services: • may appear and disappear • may not be realiable/trustworthy • can be located worldwide • are subject to communication via network that can cause delays, failures,…

  5. Let us organize problems… • Not only the issue of inter-operability (computing across different platforms): • Loose coupling: computing across enterprise boundaries (when you use a service you must account for possible deviations from the expected behavior) • Open endedness: new services can enter, and old ones leave, while computation proceeds (you should dynamically re-build your system at run-time)

  6. An Example: Web Services • WSDL (interface definition language) • UDDI (service discovery) • SOAP (service invocation protocol) -1- -2- PUBLISH SERVICE FIND SERVICE -3- SOAP

  7. Plan of the Talk Plan of the Talk • An “open” world of services • Service composition • Orchestration (bottom-up) • Choreography (top-down) • Contract-based service discovery • Output persistency • Strong Compliance • Message Queues • Conclusion and future work

  8. Buying an electronic ticket

  9. Buying an electronic ticket Web search engines Public advertisements Friends or colleagues …

  10. Buying an electronic ticket ticketing service 1 ticketing service 2 ticketing service n

  11. Buying an electronic ticket ticketing service 1 request ticketing service 2 ticketing service n

  12. Buying an electronic ticket ticketing service 1 ticketing service 2 no ticket ticketing service n

  13. Buying an electronic ticket ticketing service 1 request ticketing service 2 ticketing service n

  14. Buying an electronic ticket ticketing service 1 ticketing service 2 no ticket ticketing service n

  15. Buying an electronic ticket ticketing service 1 ticketing service 2 request ticketing service n

  16. Buying an electronic ticket ticketing service 1 ticketing service 2 ticket ticketing service n

  17. Buying an electronic ticket[using an orchestrator]

  18. Buying an electronic ticket[using an orchestrator] request orchestrator

  19. Buying an electronic ticket[using an orchestrator] ticketing service 1 ticketing service 2 orchestrator ticketing service n

  20. Buying an electronic ticket[using an orchestrator] ticketing service 1 ticketing service 2 request request orchestrator request ticketing service n

  21. Buying an electronic ticket[using an orchestrator] ticketing service 1 ticketing service 2 orchestrator ticketing service n

  22. Buying an electronic ticket[using an orchestrator] ticketing service 1 ticketing service 2 ticket orchestrator ticketing service n

  23. Buying an electronic ticket[using an orchestrator] ticketing service 1 ticketing service 2 cancel orchestrator cancel ticketing service n

  24. Buying an electronic ticket[using an orchestrator] ticketing service 1 ticketing service 2 ticket orchestrator ticketing service n

  25. Orchestration • The orchestrator provides a new “meta”-service • Central point of coordination: it invokes several “sub”-services • The client of the “meta”-service interacts only with the orchestrator

  26. Orchestration Languages • Languages used to program orchestrators • XLANG: proposed by Microsoft in 2001 • WSFL: proposed by IBM in 2001 • WS-BPEL (formerly BPEL4WS): proposed in 2002 by a consortium including IBM, Microsoft, SAP, BEA,…

  27. XLANG: based on -calculus Start; Receive(req1,req2); ( ( Invoke(req1)@srv1; Reply(req1) ) | ( Invoke(req2)@srv2; Reply(req2) ) ); End

  28. WSFL: based on Petri-nets Receive(req1,req2) Invoke(req1)@srv1 Invoke(req2)@srv2 Reply(req1) Reply(req2)

  29. WSFL: based on Petri-nets Receive(req1,req2) Invoke(req1)@srv1 Invoke(req2)@srv2 Reply(req1) Reply(req2)

  30. WSFL: based on Petri-nets Receive(req1,req2) Invoke(req1)@srv1 Invoke(req2)@srv2 Reply(req1) Reply(req2)

  31. WSFL: based on Petri-nets Receive(req1,req2) Invoke(req1)@srv1 Invoke(req2)@srv2 Reply(req1) Reply(req2)

  32. WSFL: based on Petri-nets Receive(req1,req2) Invoke(req1)@srv1 Invoke(req2)@srv2 Reply(req1) Reply(req2)

  33. WSFL: based on Petri-nets Receive(req1,req2) Invoke(req1)@srv1 Invoke(req2)@srv2 Reply(req1) Reply(req2)

  34. WSFL: based on Petri-nets Receive(req1,req2) Invoke(req1)@srv1 Invoke(req2)@srv2 Reply(req1) Reply(req2)

  35. WSFL: based on Petri-nets Receive(req1,req2) Invoke(req1)@srv1 Invoke(req2)@srv2 Reply(req1) Reply(req2)

  36. WSFL: based on Petri-nets Receive(req1,req2) Invoke(req1)@srv1 Invoke(req2)@srv2 Reply(req1) Reply(req2)

  37. WSFL: based on Petri-nets Receive(req1,req2) Invoke(req1)@srv1 Invoke(req2)@srv2 Reply(req1) Reply(req2)

  38. WSFL: based on Petri-nets Receive(req1,req2) Invoke(req1)@srv1 Invoke(req2)@srv2 Reply(req1) Reply(req2)

  39. WSFL: based on Petri-nets Receive(req1,req2) Invoke(req1)@srv1 Invoke(req2)@srv2 Reply(req1) Reply(req2)

  40. WSFL: based on Petri-nets Receive(req1,req2) Invoke(req1)@srv1 Invoke(req2)@srv2 Reply(req1) Reply(req2)

  41. WS-BPEL: join XLANG and WSFL Start; Receive(req1,req2); ( ( Invoke(req1)@srv1;Send(intLink); Reply(req1) ) | ( Invoke(req2)@srv2; Recv(intLink); Reply(req2) ) ); End

  42. WS-BPEL • Join the WSFL and XLANG approaches • Combine Petri-nets and -calculus • Add mechanisms for event, fault, termination and compensation handling • Timed events • Long-running transactions

  43. Plan of the Talk Plan of the Talk • An “open” world of services • Service composition • Orchestration (bottom-up) • Choreography (top-down) • Contract-based service discovery • Output persistence • Strong Compliance • Message Queues • Conclusion and future work

  44. Choreography Languages • Specification language (not executable) • No central point of coordination • The composed services interact reciprocally • WS-CDL: proposed by W3C in 2004 • BPEL4Chor: recently proposed by researchers involved in WS-BPEL

  45. Web Service Choreography Description Language • Describe the interaction among the combined services from a top abstract view Choreography (e.g. WS-CDL) Top abstract view of whole system: each action is a communication involving two of its participants Orchestration (e.g. WS-BPEL) One Party detailed view of the system that orchestrates a part of it by sending (to other parties) & receiving messages

  46. Similar to Specification of Chryptographic Protocols • Protocol for the request to a trusted entity of the creation of a session key: Alice  Trent: Alice, Bob Trent  Alice: {KAB}KA , {KAB}KB Alice  Bob: {KAB}KB

  47. Similar to UML Sequence Diagrams

  48. WS-CDL • Global view of service interactions Seller Buyer Bank

  49. WS-CDL • Global view of service interactions Seller Request Buyer Bank

  50. WS-CDL • Global view of service interactions Seller Request Offer Buyer PayDescr Bank

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