31.8. Publishing and Consuming REST-Based JSON Web Services

While XML was designed primarily as a document interchange format, JSON is designed as a data exchange format. Data structures in most programming languages do not map directly to XML constructs—for example, the distinction between elements and attributes is not present in programming-language data structures. JSON is a subset of the JavaScript programming language, and its components—objects, arrays, strings, numbers—can be easily mapped to constructs in Java and other programming languages.

The standard Java libraries do not currently provide capabilities for working with JSON, but there are many open-source JSON libraries for Java and other languages; you can find a list of them at json.org. We chose the Gson library from code.google.com/p/google-gson/, which provides a simple way to convert POJOs to and from JSON.