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Realizability is Controllability
Realizability is Controllability
Realizability is Controllability
Realizability is Controllability
Realizability is Controllability
Realizability is Controllability
Realizability is Controllability
Realizability is Controllability
Realizability is Controllability
Realizability is Controllability
Realizability is Controllability
Realizability is Controllability
Realizability is Controllability
Realizability is Controllability
Realizability is Controllability
Realizability is Controllability
Realizability is Controllability
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Realizability is Controllability

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Workshop presentation given by Niels Lohmann on September 4, 2009 in Bologna, Italy at the 6th International Workshop on Web Services and Formal Methods (WS-FM 2009).

Workshop presentation given by Niels Lohmann on September 4, 2009 in Bologna, Italy at the 6th International Workshop on Web Services and Formal Methods (WS-FM 2009).

Published in: Business, Design
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  • 1. Realizability is ControllabilityNielsLohmann and Karsten Wolf<br />
  • 2. Correct Services<br />“correct” interactions<br />deadlock freedom<br />livelock freedom<br />satisfaction of temporal logic formulae<br />language inclusion<br />…<br />two ways to achieve correctness<br />correctness by verification<br />correctness by construction<br />Realizability is Controllability<br />04.09.09<br />
  • 3. Correctness by Verification<br />bottom-up approach (“interconnected models”):<br />compose given services<br />modelcheck composition<br />languages to specify interconnected models:<br />BPMN<br />BPEL4Chor<br />Petri nets, automata models, process algebras<br />Realizability is Controllability<br />04.09.09<br />
  • 4. Correctness by Construction for Choreographies <br />top-down approach (“interaction models”):<br />specify desired interactions (“choreography”)<br />project interactions to participants<br />resulting composition is correct by design<br />correctness notion:<br />realizability: are there service that implement choreography?<br />languages to specify choreographies:<br />iBPMN, BPMN 2.0<br />WS-CDL, UML collaboration diagrams, Let’s Dance<br />interaction Petri nets, message sequence charts<br />Realizability is Controllability<br />04.09.09<br />
  • 5. Correctness by Construction for Orchestrations<br />partner synthesis approach:<br />specify orchestrator services<br />synthesize compatible partner services<br />resulting composition is correct by design<br />correctness notion:<br />controllability: are there compatible partner services?<br />languages to specify choreographies:<br />BPMN<br />WS-BPEL<br />open Petri nets, service automata<br />Realizability is Controllability<br />04.09.09<br />
  • 6. Choreography<br />global specification of the interaction behavior<br />who: participants / “peers”<br />how: which message channel is used<br />when: order of messages<br />choreography = set of desired interaction sequences<br />Realizability is Controllability<br />04.09.09<br />
  • 7. Realizability<br />Can choreography be implemented by services?<br />✔<br />04.09.09<br />Realizability is Controllability<br />
  • 8. Monitor<br />decides whether interaction sequences belong to choreography<br />✔<br />✘<br />04.09.09<br />Realizability is Controllability<br />
  • 9. Monitor: Internals<br />transform choreography into deterministic finite state machine<br />04.09.09<br />Realizability is Controllability<br />
  • 10. Monitor Service<br />change perspective: monitor is a service itself<br />monitor service orchestrates the participating services<br />04.09.09<br />Realizability is Controllability<br />
  • 11. Controllability<br />asks for the existence of compatible partner services<br />?<br />?<br />04.09.09<br />Realizability is Controllability<br />
  • 12. Main Result<br />* for three notions of realizability:<br />complete realizability (= realizability)<br />distributed realizability<br />partial realizability (= local enforcability)<br />Choreography is realizable*<br />if and only if<br />monitor service is controllable.<br />04.09.09<br />Realizability is Controllability<br />
  • 13. Distributed Realizability<br />additional scenario:<br />problem: Bob and Alice need to coordinate their actions:<br />either Bob chooses “Deal” or Alice chooses “Order”<br />choreography cannot be completely realized<br />04.09.09<br />Realizability is Controllability<br />
  • 14. Distributed Realizability<br />behavior can be implemented by several tuples of services<br />each tuple specifies a coordinated set of services<br />implementation 1<br />implementation 2<br />04.09.09<br />Realizability is Controllability<br />
  • 15. Distributed Realizability<br />in hierarchy of realizabilitynotions between completeand partial realizability<br />decision algorithm provides diagnosis information:<br />“Deal” and “Order” are not independent (coordination required)<br />decision algorithm returns strongest applicable realizability notion<br />04.09.09<br />Realizability is Controllability<br />
  • 16. Asynchronous Communication<br />refine atomic interaction: decoupling of sending (!) and receiving (?)<br />algorithm remains unchanged<br />assumes bounded channels<br />04.09.09<br />Realizability is Controllability<br />
  • 17. Take home points<br />Realizability (property of choreographies) and controllability (property of orchestrations) are very closely related<br />novel concept: distributed realizability<br />uniform theory and algorithms<br />definition motivated by interaction, not by decomposition<br />Future work:<br />combination of interaction models and interconnected models<br />finish implementation of prototype<br />http://service-technology.org<br />http://slideshare.net/correctsystems<br />Thank you!<br />Questions?<br />04.09.09<br />Realizability is Controllability<br />

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