Presentation

Y. Coene, SpacebelFrascati, 28 october 2005

Service Discovery based on Standards

ESA-JRC catalogue workshop, 28 oct. 2005

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Overview Problem Service registries for SOA Standards

Ws-inspection UDDI OGC CSW RSS

A real case: the Service Support Environment Conclusions


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ProblemChallenges

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


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Service Registry

Key component of a SOA architecture Loosely coupled services Service discovery and documentation Evolution to also contain policy, governance and

security info.


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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


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WS-Inspection Language

WSIL Supported by COTS tools such as Eclipse BPEL

Designer to build workflows


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OASIS UDDI Defines protocols for

Publishing and searching services registry Controlling access to registry Distributing and delegating to other registries

Client UDDI

SOAP Request

UDDISOAP Response

UDDI RegistryNode

HTTPServer

SOAPProcessor

UDDIRegistry Service

Service DirectoryCreate, View, Update, and Deleteregistrations


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businessEntityTB993… European Space Agencywww.esa.int“ … is an international organisation..contactsbusinessServicesidentifierBagcategoryBag

+39.06.781256344281 Via Galileo, Frascati, [email protected]

Peter Smythe

businessServiceKeyNameDescriptionBindingTemplates

businessService

23T701e54683nf…Products“Cross catalogue search …BindingTemplates

BindingTemplate5E2D412E5-44EE-…http://muiscx2.esrin.esa.int:8090/soaptModelInstanceDetails

tModelInstanceInfo

4453D6FC-223C-3ED0…

http://muiscx2.esrin.esa.int/webservice/catalogue.wsdl

keyedReference

DFE-2B…DUNS45231

keyedReference

EE123…NAICS02417

tModelKeys

OASIS UDDI


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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)


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OASIS UDDI Supported by commercial Web service

development tools


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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


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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)


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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


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Service Discovery in SSEService

Partner CService

Partner BService

Partner A

Oracle Oracle BPEL PMBPEL PM

“Network of service

partners”

BPEL SolutionBPEL Solution

DesignManagement

Console

Engine

BPEL SolutionBPEL SolutionDesign

Management Console


Management Console


Management Console


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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


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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


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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


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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 ?


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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


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More info: http://services.eoportal.org [email protected] (technical officer) [email protected]

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