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Semantic Web Services: State of the Art

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Presentation at the IADIS International Conference on Internet Technologies & Society (ITS 2010) in Perth, Australia

Presentation at the IADIS International Conference on Internet Technologies & Society (ITS 2010) in Perth, Australia

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  • Till some years ago that usually meant that idiot is sitting in front of the monitor. The user was normally a human.But that changed with the introduction of service-oriented architectures in the late nineties.
  • So this lead to a situation where we now have idiots on both sides. The different systems are usually so tightly coupled that even a tiny change such as the change from a 16 bit integer to a 32 bit integer could break the whole communication and would require the recompilation of the other system. Well, this might be acceptable in a controlled enterprise environment but for sure it isn’t for Internet-scale systems.
  • So what we need is a semantic description format for Web services. There have been already a lot of proposals and they can be basically classified into general-purpose and domain-specific descriptions formats.So in the next minutes I will talk a bit about the general-purpose description formats and then conclude my talk with some words on the domain-specific formats.
  •  The thing is that all of the presented approaches assume that the service follows the RPC-style. But REST is fundamentally different as it is a resource-oriented architecture. So in my opinion all of these approaches are condemned to failure for RESTful services. I think we need something dramatically simpler for RESTful services and I believe that the description of the resource representations, i.e., the transport format, combined with the use of hypermedia should be enough to achieve a high degree of automation for RESTful services without overburdening the developers.

Transcript

  • 1. © Spreng BenSemantic Web Services State of the Art Markus Lanthaler Graz University of Technology
  • 2. Programming today is a race between software engineers striving to build bigger and better idiot-proof programs,and the Universe trying to produce bigger and better idiots. So far, the Universe is winning. [Rick Cook, The Wizardry Compiled] © Rick Harris
  • 3. SOAP + WSDL + UDDI© Capture Queen
  • 4. SOAP ≈ RPC not Web-friendly© jvs11
  • 5. REST (Representational State Transfer) specifically developed for the Web© longhorndave
  • 6. (Perceived) complexity High Low Usage of HTTP as an No, abused as Yes application protocol transport protocol Web-friendly (direct support No Yes of caches, proxies, etc.) Stateless No (most of the time) Yes Addressable resources No Yes Data handling Automatic mapping No automatism to objects (O/X) Data security WS-Security, … HTTPS SOAP REST© Michael Glasgow
  • 7. REST typically has just ahuman-readable documentation
  • 8. Most naturalregularly updated The only description WSDL WADL: closely related to by HTML SMEX-D for HTML doc. Resedel and WADL WRDL RSWS NSDL WDLcontaining hyperlinkshRESTS: microformatsproposals are hRESTS forms
  • 9. Syntactic description is not enough
  • 10. Semantic annotation of data and behavior© Clever Cupcakes
  • 11. Semantic Description Formats General-purpose Domain-specific formats formats OWL-S  Atom/RSS WSMO  OpenSearch SAWSDL  oEmbed SA-REST  … MicroWSMO WSMO-Lite
  • 12. OWL-S What does Profile the service described by How theService Process Model service works How to access Grounding the service
  • 13. WSMO Objectives a client might Goals have when consulting the service Service Ontologies DescriptionDefines the formalized Description of servicesdomain knowledge Mediators Connectors between these components handles heterogeneities allows loose coupling
  • 14. SAWSDL modelReference liftingSchemaMapping loweringSchemaMappingWSDL/XSD
  • 15. MicroWSMO Model Lifting LoweringHTML + microformats (relies on hRESTS)
  • 16. SA-REST Operation Action Input/Output/Fault LiftingHTML + RDFa Lowering
  • 17. WSMO-Lite Functional Functionality the Semantics service offers Information Behavioral Model SemanticsData model for input, How has a client to output and fault talk to the service messages Non-functional Descriptions Non-functional properties, e.g. QoS or pricing
  • 18. Possible to create matching stacks for SOAP and REST Ontology, e.g. WSMO-Lite annotations point toSAWSDL Semantic annotation MicroWSMO extends extends WSDL Service interface description hRESTS
  • 19. © Nesster All of these approaches assume a RPC-style service. REST is different.
  • 20. Domain-specific Description Formats Atom/AtomPub OpenSearch Atom, OpenSearch + Linked Open Data© Dave Joyce
  • 21. Thank You© 2010, Markus Lanthaler. Some Rights Reserved.http://creativecommons.org/licenses/by-nc-sa/3.0/
  • 22. © Michael SauersMarkus LanthalerMarkus.Lanthaler@student.TUGraz.at
  • 23. Image Credits (1) http://www.flickr.com/photos/sprengben/4550315185/ (2) http://www.flickr.com/photos/rickharris/3241285917/ (4) http://www.flickr.com/photos/uaeincredible/64162372/ (4) http://www.flickr.com/photos/uaeincredible/64162372/ (5) http://www.flickr.com/photos/jvs11/4253275748/ (7) http://www.flickr.com/photos/davidw/3501319155/ (8) http://www.flickr.com/photos/glasgows/2200685325/(12) http://www.flickr.com/photos/clevercupcakes/4397152402/(21) http://www.flickr.com/photos/nesster/3168425434/(22) http://www.flickr.com/photos/deapeajay/2597109669/(24) http://www.flickr.com/photos/travelinlibrarian/223839049/(27) http://www.flickr.com/photos/arenamontanus/2530501831/(28) http://www.flickr.com/photos/mdid/2698688454/(30) http://www.flickr.com/photos/luisbg/2072134438/
  • 24. Bonus Slides
  • 25. Use lifting/lowering schemas Translation between service’s native and ontology’s format© Anders Sandberg
  • 26. Data mediation/integration is a common and still open problem© mdid
  • 27. Publishers are willing to annotatetheir data if there is an incentive Facebook’s Open Graph Protocol was implemented … and it’s in over 50,000 Web sites simple enough within the first week [http://developers.facebook.com/blog/post/379]
  • 28. © Luis de Bethencourt “We know the hard things arepossible, we just have to make the easy things easy.” [Norman Walsh, 2006]