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  • 05/06/10
  • 05/06/10
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  • 05/06/10 EO Ground segment modules, with standard internal interfaces EXTERNAL INTERFACES that allow the interoperability between different Ground Sgements. Indicate which are the level of co-operation and interoperability that will allow the users to improve the data access and data sustainability
  • 05/06/10
  • 05/06/10
  • 05/06/10

Transcript

  • 1. Y. Coene, Spacebel Frascati, 28 october 2005 Service Discovery based on Standards
  • 2. Overview
    • Problem
    • Service registries for SOA
    • Standards
      • Ws-inspection
      • UDDI
      • OGC CSW
      • RSS
    • A real case: the Service Support Environment
    • Conclusions
  • 3. Problem
    • Challenges
    • Discover (Web) services available in SOA
    • Discover composite services (workflows) available in SOA
    • Allow access from (commercial) service orchestration tools
    • Support Application to Application (A2A) interactions
    • IT Challenges
    • Use simple, standard technologies that partners can easily adopt
    • Multiple competing standards UDDI, ws-inspection, OGC CSW
    • Support in COTS needed to limit cost
  • 4. Service Registry
    • Key component of a SOA architecture
      • Loosely coupled services
      • Service discovery and documentation
      • Evolution to also contain policy, governance and security info.
  • 5. WS-Inspection Language
    • WSIL (IBM, Microsoft)
      • Simple protocol
      • Registry is a single XML file with references residing in fixed place
      • Points to WSDL end-points
      • Limited industry support (IBM, Microsoft, Oracle, ...)
      • Some public registries: Xmethods, ...
      • Not supported by a standardisation body
  • 6. WS-Inspection Language
    • WSIL
      • Supported by COTS tools such as Eclipse BPEL Designer to build workflows
  • 7. OASIS UDDI
    • Defines protocols for
      • Publishing and searching services registry
      • Controlling access to registry
      • Distributing and delegating to other registries
    Client UDDI SOAP Request UDDI SOAP Response UDDI Registry Node HTTP Server SOAP Processor UDDI Registry Service Service Directory Create, View, Update, and Delete registrations
  • 8. OASIS UDDI businessEntity TB993… European Space Agency www.esa.int “ … is an international organisation.. contacts businessServices identifierBag categoryBag +39.06.78125634 4281 Via Galileo, Frascati, I [email_address] Peter Smythe businessService Key Name Description BindingTemplates businessService 23T701e54683nf… Products “ Cross catalogue search … BindingTemplates BindingTemplate 5E2D412E5-44EE-… http://muiscx2.esrin.esa.int:8090/soap tModelInstanceDetails tModelInstanceInfo 4453D6FC-223C-3ED0… http://muiscx2.esrin.esa.int/webservice/catalogue.wsdl keyedReference DFE-2B… DUNS 45231 keyedReference EE123… NAICS 02417 tModelKeys
  • 9. OASIS UDDI
    • Managed by OASIS (BPEL, SAML, WS-Security etc.)
    • Widely adopted, public registries exist
    • Commercial and open-source registry software available: Infravio, Systinet, JUDDI, ...
    • Core Web service standard according to IT analysts (Gartner)
  • 10.  
  • 11.  
  • 12. OASIS UDDI
    • Supported by commercial Web service development tools
  • 13. Open Geospatial Consortium
    • OGC CSW
      • Registry for data and services
      • Mainly for OGC services, not related to WSDL
      • GetCapabilities() allows to discover supported (catalogue) operations
      • Calls service.GetCapabilities() to harvest metadata
      • Many profiles, bindings reduce interoperability
      • Still maturing in OWS-3 experiments (ebRIM)
      • Not supported by main Web service and BPM tool vendors
  • 14. Syndication Formats
    • Atom (IETF) and RSS (Really Simple Syndication)
      • Related to RDF (W3C)
      • Two use cases:
        • Meta-data (news) feeds exist for new books, music etc. in a library. Typically small chunks of info.
        • Amazon.com search results in RSS format
      • Discover new images/services in an EO catalogue?
        • Only suitable when limited quantity of items published per day.
      • Many clients available, allowing for syndication (i.e. combination of data channels)
  • 15. DISCO
    • Similar approach as WSIL
    • Microsoft specification (XML)
    • Service Discovery for .NET
    • Single document with links to .XSDL files
    • DISCO file understood by Visual Studio
  • 16. Service Discovery in SSE Service Partner C Service Partner B Service Partner A Oracle BPEL PM “ Network of service partners ” BPEL Solution Design Management Console Engine
  • 17. Standard "Pull" Strategy
    • W3C
      • SOAP, WSDL, XML Schema, ws-addressing
    • OASIS
      • BPEL
    • OGC
      • GML, WMS, WMS-context
      • WCS, WCTS (from BPEL)
    • Other
      • Alexandria gazetteer
      • Ws-inspection
      • RSS, WSIF
      • WS-I (Basic Profile)
    • Also planned or considered:
      • OGC WFS
      • OGC CSW (client)
      • OGC Gazetteer
      • LDAP, SAML
      • Ws-security, UDDI
      • RDF, RDFS, OWL, OWL-S
      • Google KML
  • 18. Service Discovery in SSE
    • WSIL Registry at services.eoportal.org
      • Includes links to service WSDL files
      • Accessible from Eclipse BPEL Designer
    • UDDI Registry v2 (JUDDI) to be available soon.
      • With organisations
      • With services and their WSDL file
      • Accessible from JDeveloper BPEL Designer
      • Issue with service taxonomy
  • 19.  
  • 20.  
  • 21. Service Discovery in SSE
    • Interface with OGC CSW for discovery and storage of WMS services
      • WMS layers as background for service results
      • Not planned but feasible
      • Services currently taken from a configuration file
  • 22. Conclusion
    • Several open questions:
      • Which "standards" or "profiles" to be used to be interoperable ?
      • Data and services to be dealt with same standard ?
      • Service taxonomy interoperability ?
  • 23. Conclusion
    • Selection criteria for "service discovery" spec:
      • In-line with main IT standards for Web services
      • If multiple profiles, bindings or non-compatible versions: a single choice is to be made.
      • Allow use of cheap COTS for development and deployment
      • Should allow non-intrusive addition of identity mgt, Web service management and policy inforcement COTS
      • Should be understood by service chaining COTS
  • 24. Service Discovery in SSE
    • More info:
      • http://services.eoportal.org
      • [email_address] (technical officer)
      • [email_address]