Spring Web Services together with JAXB 2.0 provides a convenient way to implement POX Web Services in Java.

POX means Plain Old XML, and a POX Web Service is a protocol based on sending XML over HTTP without using any well-known protocol framework like SOAP or XML-RPC.

First you have to define annotated JAXB classes for all XML request and response messages. If you have a schema, you can generate them with the xjc tool. Or you can create and annotate them manually. It can be a good idea to make one abstract base class for all requests, and one for all responses.

You can implement RESTful Web Services in Java using the JAX-RS framework.

JAX-RS is part of the JavaEE 6 platform. But if you are not using a JavaEE 6 application server, you can use the reference implementation Jersey and embed it in any web application server.

However, it’s quite awkward to produce JSON output from Jersey.

Jersey has some support for producing JSON via JAXB, but to get the NATURAL encoding (which you probably want) you need JAXB 2.1. And that can be problematic since JAXB 2.0 is bundled with JavaSE 6 and with some application servers (such as WebLogic). Overriding that with a later version of JAXB can be really difficult. Using JAXB is also a bit clumsy if you only want to produce JSON.