Behavioral Constraints for Services
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The document discusses behavioral constraints for services in the context of service-oriented architecture (SOA), focusing on controllability and correctness criteria to avoid deadlocks in service compositions. It highlights various applications such as service validation, operating guideline restrictions, service selection, and construction, along with methods to describe desired behaviors through constraint nets and automata. Key takeaways include enhancing expressiveness of constraints and identifying reasons for unsatisfactory constraints in service interactions.
Behavioral Constraints for Services
- 2. Analyzing Interacting Services Behavioral Constraints for Services ! Controllability: a correctness criterion for a service P R Composition P!R is free of deadlocks ! Operating Guideline: characterization of all partners RR RR OGP characterizes all partners of P ! At BPM 2006: Algorithms, Implementation, and a link to BPEL (“Analyzing Interacting BPEL Processes”) 2
- 3. Motivation for Today Behavioral Constraints for Services ! Operating Guideline characterizes all partners RR RR ! Can be thousands… ! Are all intended? ! Is a certain feature usable? This Talk: Refine controllability + show applications to SOA ! Business rules Service Broker ! Scenarios find publish ! Causalities Service Service Requester bind Provider ! Constraints 3
- 4. Constraints for Services Behavioral Constraints for Services Exclude or enforce actions of provider P with respect to a requestor R P t7 must fire always receive an order t6 must not fire never send an error message 4
- 5. Constraint Net Behavioral Constraints for Services ! Describe desired behavior as constraint net: C transitions of P C = “Firstly, fire either t1 or t2, then fire either t3 or t4.” 5
- 6. Product of P and C Behavioral Constraints for Services ! “Synchronize” P and C via transition labels 6
- 7. Product of P and C Behavioral Constraints for Services ! “Synchronize” P and C via transition labels P"C final marking 7
- 8. First Results Behavioral Constraints for Services Service Broker Applications to SOA: find publish 1. Validation of services Service Service 2. Restriction of OGs Requester bind Provider 8
- 9. Application 1: Service Validation Behavioral Constraints for Services ! Services are subject to change Not every P1 P2 P3 change is an improvement Goal: make sure the core features are still possible / unwanted behaviors are still impossible Solution: 1. Describe feature or “anti-feature” as constraint net 2. Check if product net is controllable/uncontrollable 9
- 10. Application 1: Service Validation Behavioral Constraints for Services ! Services are subject to change Not every P1 P2 P3 change is an improvement This is not testing! Goal: make sure the core features are still possible / Constraints do not need unwanted behaviors are a complete describe still impossible conversation! Solution: 1. Describe feature or “anti-feature” as constraint net 2. Check if product net is controllable/uncontrollable 10
- 11. Application 2: OG Restriction Behavioral Constraints for Services Broker organizes specialized repository: ! ! ! Mastercard payment only ! invoice after delivery ! no o!ering of certain products ! order can always be withdrawn !… Solution: Add constraint to service, re-calculate and publish OG Advantage: Many published (restricted) OGs for same service 11
- 12. Constraints for Services Behavioral Constraints for Services ! ServiceP itself might not be accessible ! Apply constraint to its published OGP OGP ! Only communicating transitions can be constrained! 12
- 13. Constraint Automaton Behavioral Constraints for Services ! Describe desired communicational behavior as constraint automaton C! ?r regular customer ?p premium customer !cod cash on delivery !cc credit card 13
- 14. Product of Operating Guideline and Constraint Automaton Behavioral Constraints for Services ! “Standard” product automaton ?r regular customer ?p premium customer C! !cod cash on delivery !cc credit card OGP 14
- 15. Product of Operating Guideline and Constraint Automaton Behavioral Constraints for Services ! “Standard” product automaton OGP"C! ?r regular customer ?p premium customer !cod cash on delivery !cc credit card 15
- 16. Further Results Behavioral Constraints for Services Service Broker Applications to SOA: find publish 3. Selection of services Service Service 4. Construction of services Requester bind Provider 16
- 17. Service Discovery in a Nutshell Behavioral Constraints for Services Broker has a repository of Operating Guidelines 1. Send model of requestor to the broker P P P P R P P P P P P 2. Broker matches service R P with OGs in repository P P 3. These OGs are from “fitting” providers 17
- 18. Application 3: Service Selection (1) Behavioral Constraints for Services Goal: Only return services satisfying a constraint ! Describe constraint as constraint automaton C"P P C"P C"P P P C C"PP R C"PP PC"P C"P P C"P P C"P P C"P P C"P P ! Brokercalculates the product C"P C"P P P ! Matching 18
- 19. Application 3: Service Selection (2) Behavioral Constraints for Services Goal: Only return services satisfying a constraint ! Describe constraint as constraint net ! Requester calculates the product P P P C P " P P P R P P P P P P ! Matching 19
- 20. Application 4: Service Construction Behavioral Constraints for Services Goal: Find services fulfilling a constraint ! Describe constraint as constraint automaton ! Broker calculates the product C"P P ! Remove empty OGs C"P C"P P P C"P P C C"PP PC"P C"P P C"P P C"PP C"P P I want C"P P (to receive) C"P C"P P P These services co!ee! provide co!ee. 20
- 21. Take-Home Points Behavioral Constraints for Services ! Two simple constructions, four nice applications Service Broker Selection find publish Restriction Service Service Construction Requester bind Provider Validation !A step towards service composition Open Tasks ! Enhance expressiveness of constraints (LTL, CTL, …) ! Diagnosis results: Why is constraint unsatisfiable? Thank you very much! Any Questions? 21