Java Web Services: Up and Running, 2nd Edition

What’s Next?

JAX-WS has two distinct but related APIs for SOAP-based web services. One API, with annotations such as @WebService and @WebMethod, focuses on what might be called the application level. On the service side, annotations are used to create web services and to specify their operations. Additional annotations such as @WebParam are available for fine-tuning and documenting different aspects of a service and its operations. On the client side, the application API enables clients to draw upon wsimport-generated classes to access a SOAP-based service and to invoke its operations. A central feature of the application level is the WSDL contract, which captures in XML the service and its operations, including essential details such as the invocation syntax for the service operations, the encoding/decoding scheme for data types, the transport used for messages, and the service endpoint. Frameworks such as JAX-WS and DotNet come with utilities that put the WSDL to practical use.

A major appeal of the application level in JAX-WS is that the SOAP itself—the XML—remains hidden on the service and the client sides. The underlying SOAP libraries serialize from Java into XML and deserialize from XML into Java, thereby allowing both service and service client to work in Java data structures and in familiar Java programming idioms. JAX-B and related utilities allow REST-style services in Java to work around the XML or JSON payloads typical of REST-style services, but JAX-WS, which uses JAX-B ...