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Discovering E-Services Using UDDI in SELF-SERV

This paper provides an overview of SELF-SERV, a framework for dynamic provisioning of web services, and explores the use of UDDI for service discovery.

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Discovering E-Services Using UDDI in SELF-SERV

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  1. Discovering E-Services Using UDDI in SELF-SERV Quan Z. Sheng, Boualem Benatallah, Rayan Stephan, Eileen Oi-Yan Mak, Yan Q. Zhu School of Computer Science and Engineering The University of New South Wales Sydney, Australia Beijing, 2002

  2. Beijing, 2002 Outline • SELF-SERV overview • Simple Object Access Protocol (SOAP) • Web Service Description Language (WSDL) • Universal Description, Discovery and Integration (UDDI) • Service Discovery Engine in SELF-SERV • Conclusion

  3. Beijing, 2002 SELF-SERV overview • SELF-SERV (compoSing wEb accessibLe inFormation & buSiness sERVices) is a framework for dynamic and peer-to-peer provisioning of Web services. • SELF-SERV distinguishes three types of services: elementary services, composite services, and service communities. • Composite service aggregates multiple Web service, based on statecharts. • Service community is a powerful concepts for composing potential large number of dynamic services.

  4. Beijing, 2002 SELF-SERV overview Architecture User Interface UDDI Registry Service Manager Communication Bus Service Community Composite Service Elementary Service

  5. SELF-SERV Service Deployer Beijing, 2002 SELF-SERV overview Architecture (cont.) Service Manager SELF-SERV Interface Service Discovery Engine UDDI Registry requests/results service descriptions Service Editor Communication Bus C3 Communities C2 C1 CS1 Composite services CS2 Pool of Services is registered with is composed of Elementary services ES1 ES2 ES4 ES3 applications workflow database web-accessible programs Legend Coordinator.1 Coordinator.2 Coordinator.n Wrapper

  6. Beijing, 2002 SOAP: Simple Object Access Protocol • An XML-based mechanism for exchanging structured data between network applications • composes 3 parts • envelope defines a framework for describing what is in a message and how to process it • encoding rules express instances of application-defined data types • a convention represents remote procedure calls and responses. • 2 types of messages, Request/Response

  7. Beijing, 2002 SOAP: an example of a request POST /carRenting HTTP/1.1 Host: www.axac.com Content-Type: text/xml; charset=“utf-8” Content-Length: 127 SOAPAction: “http://www.anywhere.com/rentCar” <SOAP-ENV:Envelope xmlns:SOAP-ENV=“http://schemas.xmlsoap.org/soap/envelope” SOAP-ENV:encodingStyle=“http://schemas.xmlsoap.org/soap/encoding”> <SOAP-ENV:body> <m:rentCar xmlns:m=“http://www.anywhere.com/rentCar”> <customer>Boualem Benatallah</customer> <rentalDate>18/05/2002</rentalDate> <returnDate>20/05/2002</returnDate> </m:rentCar> </SOAP-ENV:Body> </SOAP-ENV:Envelope>

  8. Beijing, 2002 SOAP: an example of a reply HTTP/1.1 200 OK Content-Type: text/xml; charset=“utf-8” Content-Length: 234 <SOAP-ENV:Envelope xmlns:SOAP-ENV=“http://schemas.xmlsoap.org/soap/envelope” SOAP-ENV:encodingStyle=“http://schemas.xmlsoap.org/soap/encoding”> <SOAP-ENV:Body> <m:RentcarResponse xmlns:m=“http://www.anywhere.com/rentCar”> <rentalFees>234.00</rentalFees> </m:RentcarResponse> </SOAP-ENV:Body> </SOAP-ENV:Envelope>

  9. Beijing, 2002 WSDL: Web Service Description Language • A general purpose XML language for describing interface, protocol bindings and the deployment details of Web services • a WSDL document describes how to invoke a service by providing information on • the data being exchanged • the sequence of messages for an operation • the location of the service and • the description of bindings (e.g., SOAP/HTTP)

  10. Beijing, 2002 WSDL: service description structure Service Implementation Definition Service Port Service Interface Definition Binding Port Type Message Type

  11. Beijing, 2002 WSDL: elements • Types: contains the complex data types used in message • Messages: defines the input/output parameters of an operation. • Port type: defines the operations of a Web service <definitions name="carRenting" ....> <types> <schema targetNamespace="http://example.com/carRenting.xsd" xmlns="http://www.w3.org/2000/10/XMLSchema"> <element name="Customer"> <complexType> <all><element name="Name" type="string"/> <element name="CreditCardNo" type="string"/> </all> </complexType> </element> </schema> </types>

  12. Beijing, 2002 WSDL: elements (cont.) …. <message name="carRentingInput"> <part name="customer" element="tns:Customer"/> <part name="rentalDate" type="xsd:date"/> <part name="returnDate" type="xsd:date"/> </message> <message name="carRentingOutput"> <part name="rentalFee" type="xsd:float"/> </message> <portType name="carRentingPortType"> <operation name="RentCar"> <input message="tns:carRentingInput"/> <output message="tns:carRentingOutput"/> </operation> </portType>

  13. Beijing, 2002 WSDL: elements (cont.) • Binding: describes the protocol, data format, security and other attributes for a particular service interface. • Port: an address for a binding • Service: a collection of WSDL port elements <binding name="carRentingSoapBinding" type="tns:carRentingPortType"> <soap:binding style="document” transport="http://schemas.xmlsoap.org/soap/http"/> <operation name=”rentCar"> <soap:operation soapAction="http://www.anywhere.com/rentCar"/> <input><soap:body use="literal"/></input> <output><soap:body use="literal"/></output> </operation> </binding> … <service name="CarRentingService"> <port name="carRentingPort" binding="tns:carRentingSoapBinding"> <soap:address location="http://example.com/carRenting"/> </port> ... </service>

  14. Beijing, 2002 UDDI: Universal Description, Discovery and Integration • UDDI is a specification that defines a service registry of available Web services • Jointly proposed by Microsoft, Ariba and IBM • SOAP can be used to query UDDI for services • UDDI is defined through an XML schema, identifying 4 core types of information • UDDI APIs specification: publishing/discovering (e.g., UDDI4J)

  15. Beijing, 2002 UDDI: data structure businessEntity tModel businessService bindingTemplate

  16. Beijing, 2002 UDDI: an example of business registration <businessList generic=“1.0” operator=“Microsoft operator” truncated=“false” xmlns=“urn:uddi-org:api”> <businessInfos> <businessInfo businessKey=“089B5-ER8-AC09-599CF7”> <name>Anywhere Ltd</name> <description xml:lang=“en”>all kinds of cars, trucks, motorbikes for renting</description> <serviceInfos> <serviceInfo businessKey=“ 089B5-ER8-AC09-599CF7” serviceKey=“12FF-2AF3-45FB-09AF7”> <name>carRental</name> </serviceInfo> …………. </serviceInfos> </businessInfo> </businessInfos> </businessList>

  17. Beijing, 2002 UDDI: an example of SOAP message acquiring information from the UDDI Registry <Envelope xmlns:s=“http://schemas.xmlsoap.org/soap/envelope”> <Body> <find_business xmlns=“urn:uddi-org:api” generic=“1.0”> <name>Anywhere Ltd</name> </find_business> </Body> <Envelope> For details http://www.uddi.org http://www-3.ibm.com/services/uddi

  18. Beijing, 2002 Integrating UDDI with WSDL and SOAP Service Provider Invoke Publish SOAP Request SOAP Request SOAP Response SOAP Response WSDL UDDI Registry SOAP Request Service Requestor SOAP Response WSDL Find Service registration and discovery

  19. Beijing, 2002 Service Discovery Engine in SELF-SERV • Service discovery engine facilitates service advertisements and discovery. • UDDI, together with WSDL and SOAP are used to implement the discovery engine. • IBM Web Service ToolKit (WSTK) 2.4 benefits a lot of the implementation.

  20. Beijing, 2002 Service Discovery Engine in SELF-SERV (cont.) • IBM WSTK is a showcase package for Web service related emerging technologies. It provides several tools. • A lightweight application server called “embedded WebSphere”. • A WSDL generation tool can encapsulate legacy code (e.g., Java classes, COM) as Web services. • The UDDI4J (a Java API) enables operations to UDDI registry.

  21. Beijing, 2002 Service Discovery Engine in SELF-SERV (cont.) public class publishService{ String serviceDefinitionWSDL=”http://www.cse.unsw.edu.au/SELFSERV/wsdl/carRental.wsdl” String serviceInterfaceWSDL=”http://www.cse.unsw.edu.au/SELF-SERV/wsdl/carRental-interface.wsdl”; String soapRouter=”http://www.cse.unsw.edu.au/soap/servlet/rpcrouter”; String serviceDeployment=”http://www.cse.unsw.ed.au/SELFSERV/ wsdl/deploymentDescriptor.xml”; String inquiryURL=”http://www.cse.unsw.edu.au/services/uddi/inquiryapi”; String publishURL=”https://www.cse.unsw.edu.au/services/uddi/publishapi”; ServiceRegistryProxy srp = new ServiceRegistryProxyinquiryURL, publishURL, username, password); CategoryList spCatList = new CategoryList(); spCatList.addCategory(TModelKeyTable.UNSPSC, ”84121”, TModelKeyTable.UNSPSC_TMODEL_KEY); ServiceProvider sp=new ServiceProvider(“CarRental”, “SELF-SERV service provider example”, spCatList); sp=srp.publish(sp); ServiceInterface si=new ServiceInterface(serviceInterfaceWSDL); si=srp.publish(si); CategoryList sdCatList=new CategoryList(); sdCatList.addCategory(TmodelKeyTable.UNSPSC, “84121”, TmodelKeyTable.UNSPSC_TMODEL_KEY); SOAPServiceDefinition sd=new SOAPServiceDefinition(serviceDefinitionWSDL, sdCatList, serviceDeployment, soapRouter); sd.createServiceManagerProxy().deployService(sd); srp.publish(sp, sd);} • Creating WSDL descriptions for Web services • using IBM WSDL generation tool • Deploying and publishing Web service A Java code fragment for publishing a Web service

  22. Beijing, 2002 Service Discovery Engine in SELF-SERV (cont.) A screen snapshot for service registry.

  23. Beijing, 2002 Service Discovery Engine in SELF-SERV (cont.) Locate a service Execute the service A screen snapshot for service discovery and invocation.

  24. Beijing, 2002 Conclusion • Present the design and implementation of the Service Discovery Engine in SELF-SERV • Show how UDDI, WSDL and SOAP complement each other in Web service advertisement and discovery • This work is one part of a large research project SELF-SERV. Other works of SELF-SERV have also published in IEEE ICDE02, VLDB2002 etc.

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