Java API for RESTful Web Services

JAX-RS: Java API for RESTful Web Services (JAX-RS) is a Java programming language API spec that provides support in creating web services according to the Representational State Transfer (REST) architectural pattern.^[1] JAX-RS uses annotations, introduced in Java SE 5, to simplify the development and deployment of web service clients and endpoints.

From version 1.1 on, JAX-RS is an official part of Java EE 6. A notable feature of being an official part of Java EE is that no configuration is necessary to start using JAX-RS. For non-Java EE 6 environments a (small) entry in the web.xml deployment descriptor is required.

Specification

JAX-RS provides some annotations to aid in mapping a resource class (a POJO) as a web resource. The annotations include:

• @Path specifies the relative path for a resource class or method.
• @GET, @PUT, @POST, @DELETE and @HEAD specify the HTTP request type of a resource.
• @Produces specifies the response Internet media types (used for content negotiation).
• @Consumes specifies the accepted request Internet media types.

In addition, it provides further annotations to method parameters to pull information out of the request. All the @*Param annotations take a key of some form which is used to look up the value required.

• @PathParam binds the method parameter to a path segment.
• @QueryParam binds the method parameter to the value of an HTTP query parameter.
• @MatrixParam binds the method parameter to the value of an HTTP matrix parameter.
• @HeaderParam binds the method parameter to an HTTP header value.
• @CookieParam binds the method parameter to a cookie value.
• @FormParam binds the method parameter to a form value.
• @DefaultValue specifies a default value for the above bindings when the key is not found.
• @Context returns the entire context of the object (for example @Context HttpServletRequest request).

JAX-RS 2.0

In January 2011 the JCP formed the JSR 339 expert group to work on JAX-RS 2.0.^[2] The main targets are (among others) a common client API and support for Hypermedia following the HATEOAS-principle of REST. In May 2013, it reached the Final Release stage.^[3]

Implementations

Implementations of JAX-RS include:^[4]

• Apache CXF, an open source Web service framework
• Jersey, the reference implementation from Sun (now Oracle)
• RESTeasy, JBoss's implementation
• Restlet
• Apache Wink, Apache Software Foundation Incubator project, the server module implements JAX-RS
• WebSphere Application Server from IBM:
  • Version 7.0: via the "Feature Pack for Communications Enabled Applications"
  • Version 8.0 onwards: natively
• WebLogic Application Server from Oracle, see notes
• Apache Tuscany (http://tuscany.apache.org/documentation-2x/sca-java-bindingrest.html)
• Cuubez framework (http://www.cuubez.com)
• Everrest, Codenvy's Implementation
• Jello-Framework, Java Application Framework optimized for Google App Engine, including a powerful RESTful engine and comprehensive Data Authorization model.

Notes

• Jersey Restful Web Services - Best Practice And Examples

References

• Hadley, Marc and Paul Sandoz, eds. (September 17, 2009). JAX-RS: Java API for RESTful WebServices (version 1.1), Java Community Process