• WSDL-Service Description:
Service Description carries information about the service such as the input or output parameter, the location of the service, port type, binding information, and so on.
• Web Services Definition Language
– http://www.w3.org/TR/wsdl/
• An XML-based language for describing Web Services
– what the service does (description)
– how to use it (method signatures)
– where to find the service
• It does not depend on the underlying protocol
• WSDL is an XML grammar for describing a web service as a collection of access endpoints.
• Capable of exchanging messages in a procedure or document-oriented fashion.
• A WSDL document is a recipe used to automate the details involved in application-to-application communication.
Anatomy of a WSDL Document
The following code shows the major elements that may appear in a WSDL document.
An asterisk (*) next to an element indicates that more than one of these elements may appear.
<definitions>
<import>*<types><schema></schema>*</types>
<message>*<part></part>*</message>
<PortType>*
<operation>*<input></input><output></output><fault></fault>*
</operation>
</PortType>
<binding>*<operation>*<input></input><output></output>
</operation>
</binding>
<service>*<port></port>*</service>
</definitions >
WSDL Elements
• Types – will give namespace and schema location.
• Message - Request/response messages.
• Operation - Name of operation.
• Port Type – Actual WebService.
• Binding – Binds on particular port.
• Port - URL of WS on which it is running.
• Service – web Service.
<definitions> Element
The <definitions> element in a WSDL document acts as a
container for the service description.
It provides a place to do global declarations of namespaces
that are intended to be visible throughout the rest of the
document.
<definitions targetNamespace="urn:3950" xmlns="http://schemas.xmlsoap.org/wsdl/"
xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/ “ xmlns:tns="urn:3950">
<import> Element
The <import> element serves a purpose similar to the #include directive in the C/C++ programming language.After the <definitions> element, we see an <import> element:
<definitions targetNamespace="urn:3950" xmlns="http://schemas.xmlsoap.org/wsdl/"
xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/“ xmlns:tns="urn:3950">
<import namespace="https://asf.gils.net/xer" location="https://asf.gils.net/xer/ez.xsd"/>
<types> Element
• The <types> element in a WSDL document acts as a container for defining the data types used in <message> elements.
• <message> elements define the format of messages interchanged between a client and a web service.
• The <types> element has zero or more <schema> sub elements.
<message> Element
• The <message> element is used to model the data exchanged as part of a web service.
• <message> elements reference the types defined in the <types> section.
• A message consists of one or more <part> subelements.
• A <part> subelement identifies the individual pieces of data that are part of this data message and the datatypes that the pieces adhere to.
<portType> Element
• The <portType> element specifies a subset of operations supported for an endpoint of a web service.
• In a sense, a <portType> element provides a unique identifier to a group of actions that can be executed at a single endpoint
<binding> Element
A <binding> element is a concrete protocol and data format specification for a <portType>element.
It is where you would use one of the standard binding extensions-HTTP, SOAP, or MIME-or create one of your own.
<service> Element
The <service> element typically appears at the end of a WSDL document and identifies a web service.
<?xml version="1.0" encoding="UTF-8"?>
<wsdl:definitions targetNamespace="http://emp" mlns:apachesoap="http://xml.apache.org/xml-soap" xmlns:impl="http://emp" xmlns:intf="http://emp" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" xmlns:wsdlsoap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<!--WSDL created by Apache Axis version: 1.4 Built on Apr 22, 2006 (06:55:48 PDT)-->
<wsdl:types>
<schema elementFormDefault="qualified" targetNamespace="http://emp" xmlns="http://www.w3.org/2001/XMLSchema">
<element name="getName">
<complexType>
<sequence>
<element name="sName" type="xsd:string"/>
</sequence>
</complexType>
</element>
<element name="getNameResponse">
<complexType>
<sequence>
<element name="getNameReturn" type="xsd:string"/>
</sequence>
</complexType>
</element> </schema> </wsdl:types>
<wsdl:message name="getNameResponse">
<wsdl:part element="impl:getNameResponse" name="parameters"/>
</wsdl:message>
<wsdl:message name="getNameRequest">
<wsdl:part element="impl:getName" name="parameters"/>
</wsdl:message>
<wsdl:portType name="employee">
<wsdl:operation name="getName">
<wsdl:input message="impl:getNameRequest" name="getNameRequest"/>
<wsdl:output message="impl:getNameResponse" name="getNameResponse"/>
</wsdl:operation>
</wsdl:portType>
<wsdl:binding name="employeeSoapBinding" type="impl:employee">
<wsdlsoap:binding style="document" transport="http://schemas.xmlsoap.org/soap/http"/>
<wsdl:operation name="getName">
<wsdlsoap:operation soapAction=""/>
<wsdl:input name="getNameRequest">
<wsdlsoap:body use="literal"/>
</wsdl:input>
<wsdl:output name="getNameResponse">
<wsdlsoap:body use="literal"/>
</wsdl:output>
</wsdl:operation>
</wsdl:binding>
<wsdl:service name="employeeService">
<wsdl:port binding="impl:employeeSoapBinding" name="employee">
<wsdlsoap:address location="http://localhost:8080/employee/services/employee"/>
</wsdl:port>
</wsdl:service>
</wsdl:definitions>
Web Service Request/ Response
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