299 words (approximately 2 mins)

WSDL – Web Service Description Language

Describes the functionality of a SOAP-based web service.

WSDL elements

  • <types> - The XML schema data types used by the web service.
  • <message> - The data elements for each operation.
  • <portType> - Defines a web service, its operations, and messages involved.
  • <binding> - The protocol and data format for each port type.

WSDL skeleton example

<definitions>

    <types>
        data type definitions........
    </types>

    <message>
        definition of the data being communicated....
    </message>

    <portType>
        set of operations......
    </portType>

    <binding>
        protocol and data format specification....
    </binding>

</definitions>

Partial WSDL example

<messagename="getTermRequest">
<partname="term"type="xs:string"/>
</message>

<messagename="getTermResponse">
<partname="value"type="xs:string"/>
</message>

<portType name="glossaryTerms">
    <operation name="getTerm">
    <inputmessage="getTermRequest"/>
    <outputmessage="getTermResponse"/>
    </operation>
</portType>

From https://www.w3schools.com/xml/xml_wsdl.asp

Types of portType

  • One-way - The operation can receive a message but will not return a response
  • Request - responseThe operation can receive a request and will return a response
  • Solicit - responseThe operation can send a request and will wait for a response
  • Notification - The operation can send a message but will not wait for a response

WSDL Binding to SOAP

WSDL bindings define the message format and protocol details for the web service:

<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">
        <inputmessage="getTermRequest"/>
        <outputmessage="getTermResponse"/>
    </operation>
</portType>

<binding type="glossaryTerms" name="b1">
<soap:bindingstyle="document"
 transport="http://schemas.xmlsoap.org/soap/http"/>
<operation>
    <soap:operationsoap Action="http://example.com/getTerm"/>
    <input><soap:body use="literal"/></input>
    <output><soap:body use="literal"/></output>
</operation>
</binding>

From https://www.w3schools.com/xml/xml_wsdl.asp

binding element attributes

  • name - the service’s name
  • type - the service’s port (like glossaryTerms)

soap:binding element attributes

Web Services Description Language (WSDL)

  • XML-based interface description language
  • Services in WSDL are a collection of endpoints called ports
  • Port—network address + reusable binding
  • Messages—abstract descriptions of data being exchanged
  • Port types—abstract collections of supported operations
  • Reusable binding—concrete protocol + data format specification
  • Operations and messages are bound to concrete network protocol and message format