Providing SOAP-Based Web Services - Java SOA - page 443

the body, any attachments, and so on. A DataSource works with HTTP bindings to provide
an abstraction of an arbitrary collection of data, providing access to the data in the form of
InputStream and OutputStream .
Working with a Provider requires detailed knowledge of the structure of the payload or mes-
sage.
Creating a Provider<T>
To create a provider, you must do three things:
1. Supply a public no-arg constructor.
2. Implement the Provider<T> interface, supplying one of the three acceptable values for
the type parameter.
3. Annotate the class with the @WebServiceProvider annotation.
Along with the @WebServiceProvider interface, the developer can supply a
@javax.xml.ws.Service.Mode annotation with one of two values: Mode.PAYLOAD or
Mode.MESSAGE . This value indicates the view of the data the provider instance will have ac-
cess to.
Using Mode.PAYLOAD will give the provider access to only the children of the SOAP body ele-
ment. Using Mode.MESSAGE gives the provider the entire SOAP envelope, including headers.
Note that here my example uses SOAP, but the MESSAGE mode is actually intended in a more
general way, meaning that it applies to the protocol message itself, whatever that protocol is.
The default value is PAYLOAD .
NOTE
With a provider, you are also allowed to use handlers. Handlers are discussed further in Implementing
Server-Side Handler Chains .
Example 7-10 shows the basic WSDL that you'll write by hand. Your Provider will indicate
that it conforms to that WSDL using the wsdlLocation property. Because the provider is not
an EJB, you'll just package this in a WAR, and have your Ant script place the WSDL in the
WEB-INF/wsdldirectory. Your service interface indicates that a request should contain a user-
name, and if the service authorizes the user, it will return an SSO token placed in the header
as well as a child of the SOAP body indicating the role that user is in.
Example7-10.The WSDL for an authorizer service