WEB SERVICE DESCRIPTION LANGUAGE WSDL

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WEB SERVICE DESCRIPTION LANGUAGE( WSDL)

• -SIVA SAGAR TELLA

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Overview

• What is WSDL?
• Why WSDL?
• Elements of WSDL.
• Structure of WSDL file.
• Different Elements of WSDL file.

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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.

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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.

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Elements of WSDL File

• ltdefinitionsgt
• lttypesgt definition of types lt/typesgt
• ltmessagegtdefinition of message lt/messagegt
• ltportTypegt definition of a port lt/portTypegt
• ltbindinggt definition of a binding lt/bindinggt
• ltservicegt definition of a service lt/servicegt
• lt/definitionsgt

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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 lttypesgt,
  ltmessagesgt and ltportTypegt elements.
• Concrete Description group contains ltbindinggt and
• ltservicegt elements.

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Client Invoking a Web Service
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With WSDL Terminology
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ltdefinitionsgt 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.

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Outline of ltdefinitionsgt Element

• ltdefinitions name"DefinitionsName"
  targetNamespace"NamespaceURI" xmlnsprefix"Names
  paceURI" xmlnssoap"http//schemas.xmlsoap.org/ws
  dl/soap/" xmlnsxsdhttp//www.w3.org/2001/XMLSch
  ema
• xmlns"http//schemas.xmlsoap.org/wsdl/"gt
• lt!-- Content of the WSDL file --gt
• lt/definitionsgt

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Attributes of ltdefinitionsgt 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
• Xmlnsprefix
• states the names beginning with the
  prefix prefix belongs to the namespace
  specified by this value.

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lttypesgt 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.

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Example

• lttypesgt
• ltxsdschema targetNamespace
  "http//www.roguewave.com/webservices/examples/Wea
  therSummary.xsd"
• ltxsdcomplexType name"WeatherSummary"gt
• ltxsdelement maxOccurs"1" minOccurs"1"
  name"zipcode" nillable"true" type"xsdstring"/gt
  
• ltxsdelement maxOccurs"1" minOccurs"1"
  name"windSpeed" nillable"true"
  type"xsdunsignedInt"/gt
• ltxsdelement maxOccurs"1" minOccurs"1"
  name"sky" nillable"true" type"xsdstring"/gt
• ltxsdelement maxOccurs"1" minOccurs"1"
  name"temp" nillable"true" type"xsdint"/gt
• lt/xsdcomplexTypegt
• lt/xsdschemagt
• lt/typesgt

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lttypegt 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 xsdstring, a windSpeed element
  of type xsdunsignedInt, a sky element of type
  xsdstring, and a temp element of type xsdint.

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ltmessagegt 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.

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ltmessagegt Element Continued..

• Sample of ltmessagegt element.
• ltmessage name"MessageName"gt
• ltpart name"PartName"
  type"TypeRef"/gt
• lt/messagegt
• 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.

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Example of a ltmessagegt

• ltmessage name"getSummary"gt
• ltpart name"zipcode" type"xsdstring"/gt
  
• lt/messagegt
• ltmessage name"getSummaryResponse"gt
• ltpart name"return" typewsxWeatherSumma
  ry"/gt
• lt/messagegt
• The message named getSummary consists of a string
  named zipcode.
• The message named getSummaryResponse consists of
  a WeatherSummary named return

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ltportTypegt Element

• A port type is a named set of abstract operations
  .
• An operation is a set of messages.
• The ltportTypegt element can be compared to a
  function library (or a module, or a class) in a
  traditional programming language.
• Example
• ltportType name"nmtoken"gt
• ltoperation name"nmtoken" .... /gt
• ltinput messageinput message name"/gt
• ltoutput messageoutput message name"/gt
• lt
• lt/operationgt
• lt/portTypegt

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Example

• ltmessage name"getTermRequest"gt
• ltpart name"term" type"xsstring"/gt
• lt/messagegt
• ltmessage name"getTermResponse"gt
• ltpart name"value" type"xsstring"/gt
• lt/messagegt
• ltportType name"glossaryTerms"gt ltoperation
  name"getTerm"gt ltinput
  message"getTermRequest"/gt ltoutput
  message"getTermResponse"/gt lt/operation
• lt/portTypegt
• 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.

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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.

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One-Way

• The outline for a one-way operation is
• ltportType name"nmtoken"gt
• ltoperation name"nmtoken" .... /gt
• ltinput messagemessage name"/gt
• lt/operationgt
• lt/portTypegt
• The input element specifies the abstract message
  format for the request operation.

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Request-response Operation

• The outline for a request-response operation is
• ltportType name"nmtoken"gt
• ltoperation name"nmtoken" ....
  /gt
• ltinput messageinput message
  name"/gt
• ltoutput messageoutput message
  name"/gt
• ltfault message fault message
  name/gt
• lt/operationgt
• lt/portTypegt
• 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

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Solicit-response Operation

• The outline for a solicit-response operation is
• ltportType name"nmtoken"gt
• ltoperation name"nmtoken" .... /gt
• ltoutput messageoutput message name"/gt
• ltinput messageinput message name"/gt
• ltfault message fault message name/gt
• lt/operationgt
• lt/portTypegt

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Notification Operation

• The outline for a notification operation is
• ltportType name"nmtoken"gt
• ltoperation name"nmtoken" .... /gt
  
• ltoutput messageoutput message
  name"/gt
• lt/operationgt
• lt/portTypegt

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ltbindinggt 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.

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ltbindinggt Element Continued

• ltbinding name"nmtoken" type"qname"gt
• lt-- extensibility element--gt
• ltoperation name"nmtoken"gt
• ltinput name"nmtoken"? gt
• lt-- extensibility element--gt
• lt/inputgt
• ltoutput name"nmtoken"? gt
• lt-- extensibility element--gt
• ltoutputgt
• ltfault name"nmtoken"gt
• lt-- extensibility element--gt
• ltfaultgt
• lt/operationgt
• lt/bindinggt

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Extensibility Elements

• ltsoapbindinggt
• The soapbinding element specifies
  that the binding protocol is
  SOAP.
• style attribute specifies
  whether the operation is RPC- oriented
  (messages containing parameters and return
  values) or document-oriented (message
  containing document).
• ltsoapbodygt
• The soapbody binding element provides
  information on how to assemble the
  different message parts.

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ltservicegt 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.

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ltservicegt Element Continued

• Outline of Service Element
• ltservice name"ServiceName"gt
• ltport name"PortName"
  binding"BindingRef"gt
  ltsoapaddress location"URL"/gt
• lt/portgt
• lt/servicegt
• Name attribute specifies a unique name for the
  service and port.
• Binding attribute of ltportgt specifies the binding
  reference to which the network address is
  asscociated.
• The network address of the ServiceName is
• specified by the ltsoapaddressgt elementss
  location attribute.

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References

• Links
• http//www.w3.org/TR/wsdl.html
• http//msdn.microsoft.com/archive/default.asp
  ?url/archive/en-us/dnarxml/html/wsdlexplained.asp
  
• http//www.systinet.com/doc/ssj60/primerj/pri
  merj.wsprimer.wsdl.htm
• http//www.roguewave.com/support/docs/leif/le
  if/html/leifug/B-1.html
• Books
• Author Newcomer, Eric.
• Title Understanding Web services
  XML, WSDL, SOAP, and UDDI / Eric Newcomer.