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Ulrich Küster and Birgitta König-Ries (also contains work by Michael Klein) University Jena

Dynamic Binding for BPEL Processes A Lightweight Approach to Integrate Semantics into Web Services. Ulrich Küster and Birgitta König-Ries (also contains work by Michael Klein) University Jena Germany ukuester|koenig@informatik.uni-jena.de. Introduction.

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Ulrich Küster and Birgitta König-Ries (also contains work by Michael Klein) University Jena

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  1. Dynamic Binding for BPEL ProcessesA Lightweight Approach to Integrate Semantics into Web Services Ulrich Küster and Birgitta König-Ries (also contains work by Michael Klein) University Jena Germany ukuester|koenig@informatik.uni-jena.de

  2. Introduction • SOC / web services as promising computing paradigm • loosely coupled distributed systems • combine heterogeneous systems,ease switching of components • Semantic Services • (semi-)automate time-consuming tasks (composition, selection, binding, …) • Leverage full potential of SOC • Semantic Services and Industry? • Lack of trust into reliability and correctness • Lack of comprehensive domain ontologies  high entry cost WESOA06 - Chicago, Il, USA - December 2006

  3. Goal • Provide approach for gradual transition to usage of semantic services in legacy systems • small steps, not all at once  lower entry cost • Explicitly encourage combined usage of semantics and standard technologies combine strengths  Motivating running example WESOA06 - Chicago, Il, USA - December 2006

  4. COS-tec Computer Online Store WESOA06 - Chicago, Il, USA - December 2006

  5. What is DIANE and DSD? • DIANE project goal: Complete efficient automation of service discovery, matchmaking and invocation • Diane Service Descriptions (DSD) • Own lightweight ontology language • Specific elements for service descriptions • limited expressivity • intuitive modelling • efficient but precise matchmaking WESOA06 - Chicago, Il, USA - December 2006

  6. Characteristics of DSD (1) • Fixed state ontologies • to capture world altering effects(Owned, Known, Printed, Shipped, Accessible, …) • Domain ontologies • to describe service details(domain.location, domain.economy, domain.electronics, …) WESOA06 - Chicago, Il, USA - December 2006

  7. Characteristics of DSD (2) • Set-based declarative descriptions • Amazon sells millions of articles • Shipper provide transportation to a multitude of locations  Offer described as set of possible effects • Requests envision perfect service, • but accept deviations in details  Request described as set of acceptable effects  Standard semantics: One out of the described set of effects is requested / will be created WESOA06 - Chicago, Il, USA - December 2006

  8. Characteristics of DSD (3) • Preferences in request descriptions • fuzzy sets(the higher the membership, the higher the preference) • strategies (specify how to i.e. trade-off price versus shipping time, underspecified offers, …) • unbiased, deterministic, precise matching preferably 0 (preference 1.0), but up to 20 acceptable (linearly descreasing preference) Cargo requirements must be met, shipping time is more important than price… WESOA06 - Chicago, Il, USA - December 2006

  9. Characteristics of DSD (4) • Variables • Offer-In-Variables (configure offers / provide input) • Offer-Out-Variables (provide output) • Request-In-Variables (configurable request templates) • Request-Out-Variables (require output information) Input: German city Output: Complete address in that city WESOA06 - Chicago, Il, USA - December 2006

  10. Matching DSD-Descriptions • Given fuzzy request set r and configurable offer set o solve the following problem: • Compute fuzzy containment value subsetЄ [0, 1] of o in r(How well is the offer contained in the requested effects?) • Where possible, configure o such as to maximize subset • Implementation descends through description graphs, fills variables with optimal values, recursively computes subset for each element, combines subset values according to strategies WESOA06 - Chicago, Il, USA - December 2006

  11. Integration architecture WESOA06 - Chicago, Il, USA - December 2006

  12. From BPEL to DSD Requests • Main problem: data mediation necessary, lightweight mapping from legacy COS-tec xml to DSD(and from DSD to legacy xml of shipper) • Solved by specifying mapping rules in service description's groundings WESOA06 - Chicago, Il, USA - December 2006

  13. XmlDsdMapping • empty XML message deployed at middleware • DSD variable used to fill message • variables identified by unique variable name • variable attributes specified by path to attribute • xml node specified using XPath • Marshalling/Unmarshalling • standard serialization/deserialization available • custom serialization can be plugged in • Nested mappings used to handle (nested) lists Example WESOA06 - Chicago, Il, USA - December 2006

  14. XmlDsdMapping Example ... mapping += anonymous XmlDsdMapping [ variable = $cargo, dataNodePath = "package" attributeMappings += anonymous XmlDsdAttributeMapping [ attributePath = "weight/val", subNodePath = "weight" ], attributeMappings += anonymousXmlDsdAttributeMapping [ attributePath = "dimension/length/val", subNodePath = "length" ], ... ], mapping += anonymous XmlDsdMapping [ variable = $price, dataNodePath = "maximumPrice", converterClassName = "MaxPriceConverter", converterMethodName = "convertToPriceDescription" ], ... WESOA06 - Chicago, Il, USA - December 2006

  15. Integration architecture WESOA06 - Chicago, Il, USA - December 2006

  16. Execution process • Receive template name and parameters • Lifting: Use xml to fill request template • Matchmaking: find and configure best matching offer • Send offer inputs to provider-side middleware • Lowering: Create xml invocation message • Lifting: Extract return parameters • Return parameters to client-side middleware • Lowering: Create xml reply message • System has been implemented and tested. • Elaborate scenario including selection, binding and invocation of a shipping service has been peer-reviewed within Semantic Web Services Challenge 2006 (www.sws-challenge.org) WESOA06 - Chicago, Il, USA - December 2006

  17. Summary • Goal: gradual transition to usage of semantic services in legacy systems • in particular support fully dynamic selection and binding • Presented lightweight integration of semantic requests into BPEL processes by • leveraging previous work on semantic service descriptions and matchmaking • providing easy to use, yet flexible data mediation mechanism WESOA06 - Chicago, Il, USA - December 2006

  18. Thank you for your attendance! Questions? Ulrich Küster Ulrich.Kuester@uni-jena.de DIANE project (services in ad hoc networks) http://hnsp.inf-bb.uni-jena.de/DIANE/ WESOA06 - Chicago, Il, USA - December 2006

  19. Example shipping offer offered effect(s) service instance WESOA06 - Chicago, Il, USA - December 2006

  20. Example shipping request service instance requested effect(s) preferrably 0 but up to 20 accepted WESOA06 - Chicago, Il, USA - December 2006

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