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Towards Automatic Non-Deterministic Web Service Composition Markou, G. & Refanidis, I . Dept. of Applied Informa

Towards Automatic Non-Deterministic Web Service Composition Markou, G. & Refanidis, I . Dept. of Applied Informatics, University of Macedonia, Greece. In Summary. Introduction Related Work Method of Choice Use of Standards Online Evaluation Proposed Approach Evaluation

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Towards Automatic Non-Deterministic Web Service Composition Markou, G. & Refanidis, I . Dept. of Applied Informa

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  1. Towards Automatic Non-Deterministic Web Service Composition Markou, G. & Refanidis, I. Dept. of Applied Informatics, University of Macedonia, Greece ICIW 2012 - Web Services-based Systems & Applications IV

  2. In Summary • Introduction • Related Work • Method of Choice • Use of Standards • Online • Evaluation • Proposed Approach • Evaluation • Quantitative criteria • Use case scenarios • Conclusion • Translation between AI & Web Service languages • Manual Web Service Composition module • Automatic Web Service Composition module • Application • Registry • Web Service Editor ICIW 2012 - Web Services-based Systems & Applications IV

  3. Introduction • Related Work • Method of Choice • Use of Standards • Online • Evaluation • Proposed Approach • Application • Registry • Web Service Editor • Translation between AI & Web Service languages • Manual Web Service Composition module • Automatic Web Service Composition module • Evaluation • Quantitative criteria • Use case scenarios • Conclusion ICIW 2012 - Web Services-based Systems & Applications IV

  4. Motivation • Difficult to expect from a human user /experts to manually complete the goal of a Web Service Composition (WSC) • Number of Web Services (WSs) is growing continuously  discovery phase more difficult • Ever-changing environment: WSs can change interfaces or even part of their usage multiple times throughout their lifespan • Always possible that their execution is not successful ICIW 2012 - Web Services-based Systems & Applications IV

  5. System Goals - Functionalities: • Online • Registry / Advertisement / Semantic search of Web Services • Editing of Web Services • Translation/ mapping between AI & Web Service languages • Manual Web Service composition module • Automatic Web Service composition module • Evaluation based on • Quantitative criteria • Use case scenarios ICIW 2012 - Web Services-based Systems & Applications IV

  6. Introduction • Related Work • Method of Choice • Use of Standards • Online • Evaluation • Proposed Approach • Application • Registry • Web Service Editor • Translation between AI & Web Service languages • Manual Web Service Composition module • Automatic Web Service Composition module • Evaluation • Quantitative criteria • Use case scenarios • Conclusion ICIW 2012 - Web Services-based Systems & Applications IV

  7. Method of Choice (1/2) • Method of choice? • Use of standards? • Most widespread: AI planning • Diverse • OWL-S / PDDL widely used • Other standards (e.g., WSMO) • Proprietary formats • Perhaps most notable is Sirin, et al. (2004) • From WSC problem (described in OWL-S) to HTN • Composite process that can be decomposed to simpler ones • Simple processes being atomic WSs • Reduces complexity of the planning process  • Cannot cope with non-determinism  • Planner-dependent  ICIW 2012 - Web Services-based Systems & Applications IV

  8. Method of Choice (2/2) • AI planning also used in Hoffmann, et al. (2009) • Treats the application of a WS as a belief update operation • Identifies tractable special cases of WSC • Allow for a compilation into planning under uncertainty  • Subsequent use of existing conformant planner  • PDDL-like problem descriptions  • No standardized WS description  ICIW 2012 - Web Services-based Systems & Applications IV

  9. Use of Standards • Klusch, Gerber & Schmidt (2005) and Hatzi, et al. (2011) rely on translation of OWL-S descriptions to PDDL problems  • Klusch, Gerber & Schmidt (2005): • Outputs modified PDDL files (in XML)  • Does not have evaluation on WSC problems  • Hatzi, et al. (2011) tackles uncertainty with re-planning module  • Both only address WSC problem, not other stages  ICIW 2012 - Web Services-based Systems & Applications IV

  10. Online • YaWSA (Macdonald, 2007) • Only web-based WSC system in literature with running demo  • Only implemented a WSC process (no registry, view WSs’, etc) • No longer available for public use  • Prototype web-based WSC system described in Du, Song, and Munro (2006) • Supporting multiple phases of WSC  • Public link to running demo of their implementation is not provided  ICIW 2012 - Web Services-based Systems & Applications IV

  11. Evaluation • Literature suggests a gap in the evaluation process of the current WSC systems • Many simply evaluate their methodology on a single case study, without referring to quantitative criteria, e.g., Chen, Xu, and Reiff-Marganiec (2009), McDermott (2002), McIlraith and Son (2002) • Notable exceptions: • Hoffmann, et al. (2009) : Two artificial benchmarks with different encodings and planners • Hatzi, et al. (2011): Single use case, with different number of WSs • Test collection combination of hand-tailored atomic WSs and entire domains of OWL-S Service Retrieval Test Collection (OWL-S TC) • Kona, et al. (2008): Three versions of a single use case, each suited for a mode of their WSC algorithm • Test collection: Modified version of the 2006 WS-Challenge ICIW 2012 - Web Services-based Systems & Applications IV

  12. Introduction • Related Work • Method of Choice • Use of Standards • Online • Evaluation • Proposed Approach • Application • Registry • Web Service Editor • Translation between AI & Web Service languages • Manual Web Service Composition module • Automatic Web Service Composition module • Evaluation • Quantitative criteria • Use case scenarios • Conclusion ICIW 2012 - Web Services-based Systems & Applications IV

  13. Proposed Approach - Application User email registration Based on Google Web Toolkit (GWT): Initial screen ICIW 2012 - Web Services-based Systems & Applications IV

  14. Registry (1/2) • Core of the application is based on iServe • Open platform for publishing and discovering services • WSs are semantically described in OWL-S, not Minimal Service Model • Used its web-based application for • Browsing • Querying • Uploading services • Populated the registry with version 4.0 of OWL-S TC • Made several improvements to its interface and functionality ICIW 2012 - Web Services-based Systems & Applications IV

  15. Registry (2/2) Web Service details Inline operations Semantic search alternatives ICIW 2012 - Web Services-based Systems & Applications IV

  16. Proposed Approach – WS Editor XML Editor with syntax highlighting Pre-defined OWL-S templates ICIW 2012 - Web Services-based Systems & Applications IV

  17. Translation between AI & WS Languages • AI planning language: PDDL, the de facto planning language • Specifically, NuPDDL • Compatible with PDDL2.1, retaining most of it • Capable of modeling non-deterministic action effects (one of, unknown) • WS semantic description language: OWL-S, most widely used • Heavily influenced from planning languages, such as PDDL • Partial mapping from OWL-S to PDDL exists • Part of it straightforward: • ServiceProfile input parameters  identically named ones of PDDL action • hasPrecondition/ hasEffect parameters precondition/ effect of action • Conversion of non-physical knowledge from OWL-S to PDDL problematic  Introduction of new predicate in PDDL domain? ICIW 2012 - Web Services-based Systems & Applications IV

  18. Manual WSC Module • Under implementation • Based on PetalsBPM • Modification from BPMN 2.0 editor to suit OWL-S WSC functionalities • To be compared with automatic WSC module (ease of use, speed, etc) ICIW 2012 - Web Services-based Systems & Applications IV

  19. Automatic WSC Module • Future work – Basic directions: • WSs may fail to execute correctly, e.g., • Unavailability of an atomic WS involved in the plan • Output of their successful execution is not the expected one • Generate plans tackling the most influential and likely contingencies • Proposed solution based on contingent planning • Produce seed plan • Examine for significant/ likely points of failure • Add conditional branches • Re-planning module will be integrated ICIW 2012 - Web Services-based Systems & Applications IV

  20. Introduction • Related Work • Method of Choice • Use of Standards • Online • Evaluation • Proposed Approach • Application • Registry • Web Service Editor • Translation between AI & Web Service languages • Manual Web Service Composition module • Automatic Web Service Composition module • Evaluation • Quantitative criteria • Use case scenarios • Conclusion ICIW 2012 - Web Services-based Systems & Applications IV

  21. Quantitative Criteria • Criteria to be considered: • Number of Web Services considered for WSC • Preprocessing time (parsing of ontologies’ concepts, etc) • Transformation time (of WS domain to PDDL one) • Planning time (to output a successful plan) • Optimality of the outputted plans (least WSs used to achieve the required goal) ICIW 2012 - Web Services-based Systems & Applications IV

  22. Use Case Scenarios • Based on OWL-S TC Semantic Web Services v. 4.0 (PDDL) • Each scenario uses a subset of descriptions of an OWL-S TC domain • A few semantic WS descriptions were added for testing purposes, and some were modified • Each scenario with increasing non-determinism & complexity ICIW 2012 - Web Services-based Systems & Applications IV

  23. Movie Database Scenario (1/2) • Movie database search using a (partial) movie title • Based on Communication domain: 58 semantic WSs in total • Fully deterministic - Serialized composite WS output • Retrieve comedy films with titles similar to user input • Output: • Movie titles • Pricing information (tax-free price, recommended price, etc) ICIW 2012 - Web Services-based Systems & Applications IV

  24. Movie Database Scenario (2/2) Composite Web Service (created through Manual WSC module) ICIW 2012 - Web Services-based Systems & Applications IV

  25. Online Bookstore Scenario (1/2) • Online bookstore product purchase • User wants to purchase a book from an specific online bookstore with a preferred method of payment • Preferences regarding method of payment • Based on Education domain: 285 semantic WSs in total • Non-deterministic output • Different outcomes: • Output if book in stock: • Addition of book in shopping cart • Purchase with the specified method of payment • Output information regarding it, such as its author • No output if book not in stock ICIW 2012 - Web Services-based Systems & Applications IV

  26. Online Bookstore Scenario (2/2) Composite Web Service (created through Manual WSC module) ICIW 2012 - Web Services-based Systems & Applications IV

  27. Camera Search Scenario (1/2) • Camera search and purchase • User want to purchase an analog SLR model; willing to settle for other ones if it is not in stock • User preference towards specific model • More than one sellers exist • Based on Economy domain: 359 semantic WSs in total • Possible iteration in output Web Service • Since more than one sellers exist, if product not available at one, check another • If product not found in any of the sellers, try with other versions (digital SLR, simple compact cameras) ICIW 2012 - Web Services-based Systems & Applications IV

  28. Camera Search Scenario (2/2) Composite Web Service (created through Manual WSC module) ICIW 2012 - Web Services-based Systems & Applications IV

  29. Introduction • Related Work • Method of Choice • Use of Standards • Online • Evaluation • Proposed Approach • Application • Registry • Web Service Editor • Translation between AI & Web Service languages • Manual Web Service Composition module • Automatic Web Service Composition module • Evaluation • Quantitative criteria • Use case scenarios • Conclusion ICIW 2012 - Web Services-based Systems & Applications IV

  30. Conclusion • Current WSC approaches, in general: • Do not deal with inherent non-determinism in WSC domain • Are not online, despite WS’ use & nature being web-oriented • Do not evaluate their methodology using well defined scenarios or test sets • Improvements have been made recently • Our final system is intended to be the first online and open source system supporting multiple phases of WSC • Presented scenarios provide efficient way of evaluation • Can be used by other WSC works as a common test bed ICIW 2012 - Web Services-based Systems & Applications IV

  31. Thank you for your attention! Questions? ICIW 2012 - Web Services-based Systems & Applications IV

  32. Extra Slides ICIW 2012 - Web Services-based Systems & Applications IV

  33. References: Referenced papers: • E. Sirin, B. Parsia, D. Wu, J. Hendler, and D. Nau, “HTN planning for web service composition using SHOP2”, J. Web Semant., vol. 1, no. 4, Oct. 2004, pp. 377-396. • J. Hoffmann, P. Bertoli, M. Helmert, and M. Pistore, “Message-based web service composition, integrity constraints, and planning under uncertainty: a new connection”, J. Artif. Intell. Res, vol. 35, May 2009, pp.49-117. • M. Klusch, Α. Gerber, and M. Schmidt, “Semantic web service composition planning with OWLS-Xplan”, Proc. 1st International AAAI Fall Symposium on Agents and the Semantic Web, Nov. 2005. • O. Hatzi, D. Vrakas, M. Nikolaidou, et al., “An integrated approach to automated semantic web service composition through planning”, IEEE Trans. Service Computing, April 2011, pp. 301-308. • A. Macdonald, “Service composition with hyper-programming”. Technical Report, University of St Andrews, 2007. • X. Du, W. Song, and M. Munro, “Using common process patterns for semantic web services composition”, Proc. 15th International Conference on Information Systems Development (ISD’06), Sept. 2006. • K. Chen, J. Xu, and S. Reiff-Marganiec, “Markov-HTN planning approach to enhance flexibility of automatic web service composition”, Proc. IEEE International Conference on Web Services (ICWS'09), July 2009, pp. 9-16. • D.V. McDermott, “Estimated-regression planning for interactions with web services”, Proc. Sixth International Conference on Artificial Intelligence Planning Systems (AIPS ’02), April 2002, pp. 204-211. • S. McIlraith and T. Son, “Adapting Golog for composition of semantic web services”, Proc. 8th International Conference on Principles of Knowledge Representation and Reasoning (KR2002), April 2002, pp. 482-496. • S. Kona, A. Bansal, M.B. Blake, and G. Gupta, “Generalized Semantics-Based Service Composition”, Proc. IEEE International Conference on Web Services (ICWS’08), Sept. 2008. ICIW 2012 - Web Services-based Systems & Applications IV

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