Transcript WEB SERVICE DESCRIPTION LANGUAGE ( WSDL) -SIVA SAGAR TELLA

WEB SERVICE DESCRIPTION
LANGUAGE
( WSDL)
-SIVA SAGAR TELLA
Overview
What is WSDL?
Why WSDL?
Elements of WSDL.
Structure of WSDL file.
Different Elements of WSDL file.
What is WSDL ?
WSDL stands for Web Service Description
Language.
WSDL is an XML document.
WSDL is used to describe Web services.
WSDL is also used to locate Web
services.
Why WSDL?
 Many Organizations provide web services over the
network.
 For a client to use a particular web service he has to
know the format of the request to be sent and the format
of the response that is returned.
 Client can also know the address of the web service
using WSDL.
 WSDL is an XML format for describing network services
as a set of endpoints operating on messages containing
either document-oriented or procedure-oriented
information.
 The operations and messages are described abstractly,
and then bound to a concrete network protocol and
message format to define an endpoint.
Elements of WSDL File
 <definitions>
 <types> definition of types </types>
 <message>definition of message </message>
 <portType> definition of a port </portType>
 <binding> definition of a binding </binding>
 <service> definition of a service </service>
 </definitions>
Structure of WSDL file
 The WSDL document can be divided into two
groups of sections.
1) Abstract Definition.
Platform and language independent elements are
specified.
2) Concrete Descriptions.
Platform and language dependent elements are
specified
 Abstract Definition group contains <types>, <messages> and
<portType> elements.
 Concrete Description group contains <binding> and
<service> elements.
Client Invoking a Web Service
With WSDL Terminology
<definitions> Element
Root element of the WSDL document.
Contains all other elements definitions in
the documents.
Sets the name of the WSDL document and
declares the namespaces used in the
document.
Outline of <definitions> Element
 <definitions name="DefinitionsName"
targetNamespace="NamespaceURI"
xmlns:prefix="NamespaceURI"
xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
xmlns:xsd=“http://www.w3.org/2001/XMLSchema”
xmlns="http://schemas.xmlsoap.org/wsdl/">
<!-- Content of the WSDL file -->
</definitions>
Attributes of <definitions> Element
 targetNamespace :
Specifies the name for the WSDL
definition as a whole.
All the elements in the definitions element
declare their names in the targetNamespace
 Xmlns : (Used to denote the default namespace)
states that attribute names without a namespace
qualification are in the WSDL namespace.
Default Namespace is “http://schemas.xmlsoap.org/wsdl”
 Xmlns:prefix :
states the names beginning with the prefix “prefix” belongs
to the namespace specified by this value.
<types> Element
Contains schema definitions of the data
types used in the messages that compose
the service.
WSDL uses XML Schema syntax to define
data types.
This element is optional if the service uses
the primitive data types defined by XML
Schema.
Example
 <types>
<xsd:schema targetNamespace=
"http://www.roguewave.com/webservices/examples/WeatherSummary.xsd"
<xsd:complexType name="WeatherSummary">
<xsd:element maxOccurs="1" minOccurs="1" name="zipcode"
nillable="true" type="xsd:string"/>
<xsd:element maxOccurs="1" minOccurs="1" name="windSpeed"
nillable="true" type="xsd:unsignedInt"/>
<xsd:element maxOccurs="1" minOccurs="1" name="sky" nillable="true"
type="xsd:string"/>
<xsd:element maxOccurs="1" minOccurs="1" name="temp" nillable="true"
type="xsd:int"/>
</xsd:complexType>
</xsd:schema>
</types>
<type> Element Continued..
 This types element contains a complete XML
Schema. The schema defines a single
complexType named WeatherSummary.
 The WeatherSummary type contains a “zipcode”
element of type xsd:string, a “windSpeed”
element of type xsd:unsignedInt, a “sky” element
of type xsd:string, and a “temp” element of type
xsd:int.
<message> Element
Defines the content of a message that the
service supports.
Each message holds one or more part
elements.
A part reference a parameter in the
message.
The parts can be compared to the
parameters of a function call in a
traditional programming language.
<message> Element Continued..
Sample of <message> element.
<message name="MessageName">
<part name="PartName" type="TypeRef"/>
</message>
Name Attribute:
Specify the name of the message and name of
part in the case of respective elements .
Other elements in the WSDL document use this
name to refer to this message.
Example of a <message>
 <message name="getSummary">
<part name="zipcode" type="xsd:string"/>
</message>
<message name="getSummaryResponse">
<part name="return" type=“wsx:WeatherSummary"/>
</message>
 The message named getSummary consists of a string named
zipcode.
 The message named getSummaryResponse consists of a
WeatherSummary named return
<portType> Element
 A port type is a named set of abstract operations .
 An operation is a set of messages.
 The <portType> element can be compared to a function library (or a
module, or a class) in a traditional programming language.

Example:
<portType name="nmtoken">
<operation name="nmtoken" .... />
<input message=“input message name"/>
<output message=“output message name"/>
<
</operation>
</portType>
Example
<message name="getTermRequest">
<part name="term" type="xs:string"/>
</message>
<message name="getTermResponse">
<part name="value" type="xs:string"/>
</message>
<portType name="glossaryTerms">
<operation name="getTerm">
<input message="getTermRequest"/>
<output message="getTermResponse"/>
</operation
</portType>
 Compared to traditional programming, glossaryTerms is
a function library, "getTerm" is a function with
"getTermRequest" as the input parameter and
getTermResponse as the return parameter.
Types of Operations
 One-way. The endpoint receives a message.
 Request-response. The endpoint receives a
message, and sends a correlated message.
 Solicit-response. The endpoint sends a
message, and receives a correlated message.
 Notification. The endpoint sends a message.
One-Way
The outline for a one-way operation is:
<portType name="nmtoken">
<operation name="nmtoken" .... />
<input message=“message name"/>
</operation>
</portType>
 The input element specifies the abstract message format
for the request operation.
Request-response Operation
 The outline for a request-response operation is:
<portType name="nmtoken">
<operation name="nmtoken" .... />
<input message=“input message name"/>
<output message=“output message name"/>
<fault message = “fault message name”/>
</operation>
</portType>
 The input element specifies the abstract message format for the request
operation.
 The output element specifies the abstract message format for the response
operation.
 The fault element specifies the message format for the error messages
Solicit-response Operation
 The outline for a solicit-response operation is:
<portType name="nmtoken">
<operation name="nmtoken" .... />
<output message=“output message name"/>
<input message=“input message name"/>
<fault message = “fault message name”/>
</operation>
</portType>
Notification Operation
 The outline for a notification operation is:
<portType name="nmtoken">
<operation name="nmtoken" .... />
<output message=“output message name"/>
</operation>
</portType>
<binding> Element
A binding element describes a specific
communication protocol for a portType
element.
Each binding corresponds to a portType in
the WSDL document.
The binding element describes the specific
protocol for each message in each
operation of the portType element.
<binding> Element Continued…
 <binding name="nmtoken" type="qname">
<-- extensibility element-->
<operation name="nmtoken">
<input name="nmtoken"? >
<-- extensibility element-->
</input>
<output name="nmtoken"? >
<-- extensibility element-->
<output>
<fault name="nmtoken">
<-- extensibility element-->
<fault>
</operation>
</binding>
Extensibility Elements
 <soap:binding>
The soap:binding element specifies that the binding protocol
is SOAP.
“style” attribute specifies whether the operation is RPCoriented (messages containing parameters and return
values) or document-oriented (message containing
document).
 <soap:body>
The soap:body binding element provides information on how
to assemble the different message parts.
<service> Element
A service element describes a
Web service as a collection of
port elements.
A port element defines a specific
network address for a binding.
<service> Element Continued…
Outline of Service Element:
<service name="ServiceName">
<port name="PortName" binding="BindingRef">
<soap:address location="URL"/>
</port>
</service>
 Name attribute specifies a unique name for the service
and port.
 Binding attribute of <port> specifies the binding
reference to which the network address is asscociated.
 The network address of the “ServiceName” is
specified by the <soap:address> elements’s “location”
attribute.
References
Links:
http://www.w3.org/TR/wsdl.html
http://msdn.microsoft.com/archive/default.asp?url=/archive/enus/dnarxml/html/wsdlexplained.asp
http://www.systinet.com/doc/ssj60/primerj/primerj.wsprimer.wsdl.htm
http://www.roguewave.com/support/docs/leif/leif/html/leifug/B-1.html
Books:
Author: Newcomer, Eric.
Title:
Understanding Web services : XML, WSDL, SOAP, and
UDDI / Eric Newcomer.