Java Web Services: Up and Running, 2nd Edition

A RESTful Service as a @WebServiceProvider

JAX-WS includes APIs for RESTful and SOAP-based web services, although JAX-WS seems to be used mostly for the latter. The reference implementation is Metro, which is part of the GlassFish project. Although JAX-WS technically belongs to enterprise rather than core Java, the core Java JDK (1.6 or greater) includes enough of the Metro distribution to compile and publish RESTful and SOAP-based services. JAX-RS and Restlet are state-of-the-art, high-level APIs for developing RESTful services; by contrast, the JAX-WS API for RESTful services is low-level. Nonetheless, JAX-WS support for RESTful services deserves a look, and the JAX-WS API for SOAP-based services will be the centerpiece in Chapter 4 and Chapter 5.

The JAX-WS stack reflects the view that SOAP-based services over HTTP are refinements of RESTful services. The JAX-WS API has two main annotations. A POJO class annotated as a @WebService delivers a SOAP-based service, whereas a POJO class annotated as a @WebServiceProvider usually delivers a RESTful one; however, a class annotated as a @WebServiceProvider can deliver a SOAP-based service as well. Yet another revision of the adages RESTful service, adages3, introduces the JAX-WS API for RESTful services.

In the revised adages3 service, the Adage and Adages classes are mostly unchanged from the adages2 version. One small change is that the package name goes from adages2 to adages3; another change is that the Adage list is returned as array, ...