Discovering E-Services Using Discovering E-Services Using UDDI in SELF-SERVUDDI in SELF-SERV

Quan Z. Sheng, Boualem Benatallah, Rayan Stephan, Quan Z. Sheng, Boualem Benatallah, Rayan Stephan,

Eileen Oi-Yan Mak, Yan Q. ZhuEileen Oi-Yan Mak, Yan Q. Zhu

School of Computer Science and Engineering

The University of New South Wales

Sydney, Australia

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

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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.

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SELF-SERV overview Architecture

Communication Bus

User Interface

Elementary Service Composite Service Service Community

UDDI Registry Service Manager

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SELF-SERV overview Architecture (cont.)

Service Manager

is registered with

service descriptions

Pool of Services Elementary

services

Communities

UDDIRegistry

Composite services

is composed of

Service Editor

Service Deployer

Communication Bus

Coordinator.1 Coordinator.2 Coordinator.n

Wrapper

Legend

SELF-SERV

SELF-SERV Interface

requests/results

workflow database applications web-accessible programs

Service Discovery Engine

C1 C2 C3

CS1 CS2

ES1 ES2 ES3 ES4

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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

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SOAP: an example of a request

POST /carRenting HTTP/1.1Host: www.axac.comContent-Type: text/xml; charset=“utf-8”Content-Length: 127SOAPAction: “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>

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SOAP: an example of a reply

HTTP/1.1 200 OKContent-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>

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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)

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WSDL: service description structure

ServiceImplementation

Definition

ServiceImplementation

Definition

ServiceService

PortPort

ServiceInterfaceDefinition

ServiceInterfaceDefinition

BindingBinding

Port TypePort Type

MessageMessage

TypeType

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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> Beijing, 2002

….<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>

WSDL: elements (cont.)

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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>

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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)

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UDDI: data structure

businessEntitybusinessEntity

businessServicebusinessService

bindingTemplatebindingTemplate

tModeltModel

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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>

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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/uddiFor details http://www.uddi.org http://www-3.ibm.com/services/uddi

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Integrating UDDI with WSDL and SOAP

SOAP RequestWSDL

SOAP Response

SOAP Request

Publish Invoke

Find

Service Provider

Service

Requestor

SOAP Response

SOAP Request

WSDL

SOAP Response

UDDIRegistry

Service registration and discoveryBeijing, 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.

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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.

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Service Discovery Engine in SELF-SERV (cont.)

• Creating WSDL descriptions for Web services

– using IBM WSDL generation tool

• Deploying and publishing Web service

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);}

A Java code fragment for publishing a Web serviceBeijing, 2002

Service Discovery Engine in SELF-SERV (cont.)

A screen snapshot for service registry. Beijing, 2002

Service Discovery Engine in SELF-SERV (cont.)

Locate a service

Execute the service

A screen snapshot for service discovery and invocation. 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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