To invoke a Web Service upon sending a message to a channel, there are two options - both of which build upon the Spring Web Services project: SimpleWebServiceOutboundGateway and MarshallingWebServiceOutboundGateway. The former will accept either a String or javax.xml.transform.Source as the message payload. The latter provides support for any implementation of the Marshaller and Unmarshaller interfaces. Both require the URI of the Web Service to be called.

 simpleGateway = new SimpleWebServiceOutboundGateway(uri);

 marshallingGateway = new MarshallingWebServiceOutboundGateway(uri, marshaller);

For more detail on the inner workings, see the Spring Web Services reference guide's chapter covering client access as well as the chapter covering Object/XML mapping.