introduction to the web services description language...

Introduction to the Web Introduction to the Web Services Description Services Description Language (WSDL)Language (WSDL)

Presented by Paul Kingston

AgendaAgenda

l Definition of WSDL.l Web services overview and where WSDL fits.l Dissection of the WSDL Protocol.l Demos

– Generation of code from WSDL.– Generation of WSDL from code.

l Tools that support WSDL, and other resources.l References.

Definitions of WSDLDefinitions of WSDL(taken from the specification)(taken from the specification)

l "A set of definitions". l "An XML format for describing network

services as a set of endpoints operating on messages containing either document oriented or procedure oriented information".

WSDL IS XMLWSDL IS XML

l However it is assumed that the audience know enough XML to follow along.

Web Services ModelWeb Services Model

Service Provider

Service RegistryService Requestor

Publish

WSDL in the Web Services WSDL in the Web Services ModelModel

Service Provider

Service RegistryService Requestor

WSDL + SOAP or HTTP

WSDL + UDDI

WSDL Protocol WSDL Protocol –– the what, the what, how and wherehow and where

Every WSDL file can be thought of as consisting of three basic parts:

l “what” – the operations and messages.l “how” – communications mechanism.l “where” – location of the service.

WSDL Protocol WSDL Protocol –– the whatthe what

The <types>, <message> and <portType> tags indicate the operations and what type of data will be passed.

WSDL Protocol WSDL Protocol –– the howthe how

<binding> tags indicate the what sort of transport mechanism (protocol) the service will use to communicate.

WSDL Protocol WSDL Protocol –– the wherethe where

<service> tags indicate the location of the service

WSDL Protocol WSDL Protocol –– the basicsthe basics

l All elements are set within the <definition> root element.

l The <import> element allows partitioning of a WSDL file into smaller files based on functionality.

l Extensibility elements allow for WSDL additions without rewriting the specification.

A shell WSDL file:A shell WSDL file:

<?xml version="1.0"?><definitions>

</definitions>

l The component elements can be thought of as "building on each other" as elements towards the bottom reference elements at the top.

l All elements can have child <documentation> elements which are used as comments.

<definitions> element<definitions> element<definitions

name=""(optional) targetNamespace=""(optional)

xmlns:""="" (optional - one or more) ></definitions>

l All elements have name scope (i.e. all names must be unique).

l Can also use the <import> element to import or associate a namespace with the WSDL document.

Let's assemble the <definitions> Let's assemble the <definitions> element for the example:element for the example:

<definitions

name="CurrencyExchangeService"targetNamespace="http://www.xmethods.net/sd/CurrencyExchangeService.wsdl" xmlns:tns="http://www.xmethods.net/sd/CurrencyExchangeService.wsdl" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns="http://schemas.xmlsoap.org/wsdl/">

Which gives us so far:Which gives us so far:<definitions

name="CurrencyExchangeService"targetNamespace="http://www.xmethods.net/sd/CurrencyExchangeService.wsdl"

xmlns:tns="http://www.xmethods.net/sd/CurrencyExchangeService.ws dl" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"

xmlns="http://schemas.xmlsoap.org/wsdl/">

</definitions>

<types> element<types> element<types>

<schema targetNamespace="" xmlns=""><element> (optional, one or more)

</complexType></element>

</schema></types>

<types> element (cont.)<types> element (cont.)

l Define data types which will be used in exchanged messages.

l XSD is the "preferred" type system.l The <element> tags can be used to define

composite data types (structures).l Not necessary if only using primitive data types

defined by the schema namespace.l Since our example only uses primitive types, it

does not need a <types> element.

XMLSchema typesXMLSchema typesstring

boolean decimal

float double

durationdateTime

time date

gYearMonth gYear

gMonthDay gDay

gMonth hexBinary

base64BinaryanyURI QName

NOTATION

<message> element<message> element

<message name=""><part name="" element="" (or) type=""/> (optional, one or

more)</message>

l A definition of the data exchanged between endpoints.

Let's assemble the <message> Let's assemble the <message> elements for the exampleelements for the example

</message><message name="getRateResponse">

</message>

Which gives us so far:Which gives us so far:<?xml version="1.0"?><definitions

name="CurrencyExchangeService“targetNamespace="http://www.xmethods.net/sd/CurrencyExchangeService.wsdl"xmlns:tns="http://www.xmethods.net/sd/CurrencyExchangeService.wsdl"xmlns:xsd="http://www.w3.org/2001/XMLSchema"xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"xmlns="http://schemas.xmlsoap.org/wsdl/"><message name="getRateRequest">

<part name="Result" type="xsd:float" /> </message>…

Which gives us so far (cont):Which gives us so far (cont):

</binding><service></service>

</definitions>

<portType> element<portType> element

<portType name=""><operation name=""> (optional, one or more)

<input name=""(optional) message=""> (optional)<output name=""(optional) message=""> (optional)<fault name="" message=""> (optional, one or more)

</operation></portType>

<portType> element (cont.)<portType> element (cont.)

l Defines a set of operations.l Defines input and output to each operation.l portTypes are often referred to as

"endpoints" in the specification.

Transmission PrimitivesTransmission Primitives

l One-way - the portType receives a message.l Request-response - the portType receives a

message then sends a related message.l Solicit-response - the portType sends a message,

then receives a related message.l Notification - the portType sends a message.

These primitives are referred to as "operations" in WSDL.

Let's assemble the <portType> Let's assemble the <portType> element for the exampleelement for the example

Which gives us so far:Which gives us so far:<?xml version="1.0"?><definitions

</definitions>

<binding> element<binding> elementNote that this element is protocol-specific. <--extensibility element--> denotes

protocol information.

<binding name="" type=""><--extensibility element--> <operation name=""> (optional, one or more)

<input name=""> (optional)<--extensibility element-->

</input><output name=""> (optional)

<--extensibility element--></output><fault name=""> (optional, one or more)

<--extensibility element--></fault>

</operation></binding>

<binding> element (cont.)<binding> element (cont.)

l Defines the protocol and message format for a givenportType.

l The type attribute defines the portType.l The binding specifies exactly one protocol.

Protocols built into the WSDL Protocols built into the WSDL specificationspecification

l SOAPl HTTP GET & POSTlMIMEl Others can be added at any time, by

anybody using extensibility elements.

Let's assemble the <binding> Let's assemble the <binding> element for the exampleelement for the example

<soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http" /> <operation name="getRate">

<soap:operation soapAction="" /> <input>

<soap:body use="encoded" namespace="urn:xmethods-CurrencyExchange"encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />

</input><output>

</output></operation>

</binding>

Which gives us so far:Which gives us so far:

<?xml version="1.0"?><definitions

Which gives us so far (cont):Which gives us so far (cont):<portType name="CurrencyExchangePortType">

</operation></portType><binding name="CurrencyExchangeBinding" type="tns:CurrencyExchangePortType"><soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http" /> <operation name="getRate">

</input><output>

</binding>…

…<service></service>

</definitions>

<service> element<service> element

Note that like <binding>, this element is protocol-specific. <--extensibility element--> denotes protocol information.

<service name=""><port name="" binding=""> (optional, one or more)

<--extensibility element--></port>

</service>

<service> element (cont.)<service> element (cont.)

l Defines a collection of ports.l Defines an address from which to access the service.l Each port can specify, at most one address.l Multiple ports can be specified with different addresses

and/or protocols to offer alternatives to client applications.

Let's assemble the <service> Let's assemble the <service> element for the exampleelement for the example

<documentation>Returns the exchange rate between the two currencies

</documentation> <port name="CurrencyExchangePort"

binding="tns:CurrencyExchangeBinding"><soap:address location="http://services.xmethods.net:80/soap" />

</port>

</service>

Which gives us finally:Which gives us finally:<?xml version="1.0"?><definitions

Which gives us finally (cont):Which gives us finally (cont):<portType name="CurrencyExchangePortType">

</operation></portType><binding name="CurrencyExchangeBinding" type="tns:CurrencyExchangePortType"><soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http" /> <operation name="getRate">

</input><output>

</binding>…

Which gives us finally (cont):Which gives us finally (cont):

<service name="CurrencyExchangeService"><documentation>Returns the exchange rate between the two currencies</documentation> <port name="CurrencyExchangePort" binding="tns:CurrencyExchangeBinding">

<soap:address location="http://services.xmethods.net:80/soap" /> </port>

</service>

</definitions>

<?xml version="1.0"?><definitions

name="CurrencyExchangeService"targetNamespace="http://www.xmethods.net/sd/CurrencyExchangeService.wsdl"xmlns:tns="http://www.xmethods.net/sd/CurrencyExchangeService.wsdl"xmlns:xsd="http://www.w3.org/2001/XMLSchema"xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"xmlns="http://schemas.xmlsoap.org/wsdl/">

</input><output>

</binding>

<service name="CurrencyExchangeService"><documentation>Returns the exchange rate between the two currencies</documentation> <port name="CurrencyExchangePort" binding="tns: CurrencyExchangeBinding">

<soap:address location="http://services.xmethods.net:80/soap" /> </port>

</service>

</definitions>

Complete WSDL file:

Questions?Questions?

DemosDemos

• Generation of code from WSDL.• Generation of WSDL from code.

Tools supporting WSDLTools supporting WSDL

l IBM Web Services Toolkithttp://www.alphaworks.ibm.com/tech/webservicestoolkit

l Borland Jbuilderl Microsoft SOAP Toolkitl Microsoft Visual Studio .NETl Soap::Lite for Perl

http://www.soaplite.com/

l GLUE http://www.themindelectric.com/glue/index.html

l PocketSOAP http://pocketsoap.com/wsdl/

WSDL resourcesWSDL resources

l www.salcentral.com - searchable web services database

l www.xmethods.net - another searchable web services database

l www.searchWebServices.com - articles and information

Questions?Questions?

ReferencesReferenceshttp://w3.org/TR/wsdl (WSDL Specification)http://www.xmethods.nethttp://www.searchWebServices.comhttp://www.w3.org/TR/xmlschema-2/ (XML Schema Specification)Clark, D., “Next-generation web services”, IEEE Internet Computing, Vol. 6, Issue 2, pp.

12-14, March-April 2002.Glass, G., “The Web services (r)evolution: Part 2 – Hello world, Web service-style”, IBM

developerWorks, February 2001 (http://www-106.ibm.com/developerworks/webservices/library/ws-peer2/)

Glass, G., “The Web services (r)evolution: Part 4 – Web Services Description Language (WSDL)”, IBM developerWorks, February 2001 (http://www-106.ibm.com/developerworks/webservices/library/ws-peer4/)

Myerson, J., “Testing for SOAP Interoperability”, Web Services Architect, February 26, 2002(http://www.webservicesarchitect.com/content/articles/myerson02print.asp )

Hondo, M., Nagaratnam, N., Nadalin, A., “Securing Web Services”, IBM Systems Journal, Vol. 41, No. 2, 2002.

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