- The <message> element describes the data being exchanged between the Web service providers and consumers.
- Each Web Service has two messages: input and output.
- The input describes the parameters for the Web Service and the output describes the return data from the Web Service.
- Each message contains zero or more <part> parameters, one for each parameter of the Web Service’s function.
- Each <part> parameter associates with a concrete type defined in the <types> container element.
Lets take a piece of code from the Example Session:
<message name="SayHelloRequest">
<part name="firstName" type="xsd:string"/>
</message>
<message name="SayHelloResponse">
<part name="greeting" type="xsd:string"/>
</message>
Here, two message elements are defined. The first represents a request message SayHelloRequest, and the second represents a response message SayHelloResponse.
Each of these messages contains a single part element. For the request, the part specifies the function parameters; in this case, we specify a single firstName parameter. For the response, the part specifies the function return values; in this case, we specify a single greeting return value.
References
Wikipedia for WSDL
