WSDL Messaging Exchange Patterns

In WSDL, there are four basic message exchange patterns used in Web services: one-way, request-response, solicit-response, and notification.

One-way

The service receives a message. The operation therefore has a single input element.

<wsdl:definitions … >


<wsdl:portType … > *

 <wsdl:operation name="nmtoken">


<wsdl:input name="nmtoken"? message="qname"/>

 </wsdl:operation>


</wsdl:portType>

</wsdl:definitions>

Request-Response

The service receives a message and sends a response. The operation therefore has one input element, followed by one output element. To encapsulate errors, an optional fault element can also be specified.

<wsdl:definitions … >

<wsdl:portType … > *

<wsdl:operation name="nmtoken" parameterOrder="nmtokens">

<wsdl:input name="nmtoken"? message="qname"/>

<wsdl:output name="nmtoken"? message="qname"/>

<wsdl:fault name="nmtoken"? message="qname"/>*

</wsdl:operation>

</wsdl:portType>

</wsdl:definitions>

Solicit-Response

The service sends a message and receives a response. The operation therefore has one output element, followed by one input element. To encapsulate errors, an optional fault element can also be specified.

<wsdl:definitions …>

<wsdl:portType … > *

<wsdl:operation name="nmtoken" parameterOrder="nmtokens">

<wsdl:output name="nmtoken"? message="qname"/>

<wsdl:input name="nmtoken"? message="qname"/>

<wsdl:fault name="nmtoken"? message="qname"/>*

</wsdl:operation>

</wsdl:portType>

</wsdl:definitions>

Notification

The service sends a message. The operation therefore has a single output element.

<wsdl:definitions … >

<wsdl:portType … > *

<wsdl:operation name="nmtoken">

<wsdl:output name="nmtoken"? message="qname"/>

</wsdl:operation>

</wsdl:portType>

</wsdl:definitions>

Solicit-Response and Notification messaging are supported by WSDL, but they are not supported by the WS-I Basic Profile 1.0.

5.4.5 Allowed Operations

Solicit-Response and Notification operations are not well defined by WSDL 1.1; furthermore, WSDL 1.1 does not define bindings for them.

R2303 A DESCRIPTION MUST NOT use Solicit-Response and Notification type operations in a wsdl:portType definition.