2.5. JSON Parsers: Handling Serialized Data

Most web services return XML documents, but a growing number return simple data structures (numbers, arrays, hashes, and so on), serialized as JSON-formatted strings. JSON is usually produced by services that expect to be consumed by the client half of an Ajax application. The idea is that it’s a lot easier for a browser to get a JavaScript data structure from a JSON data structure than from an XML document. Every web browser offers a slightly different JavaScript interface to its XML parser, but a JSON string is nothing but a tightly constrained JavaScript program, so it works the same way in every browser.

Of course, JSON is not tied to JavaScript, any more than JavaScript is to Java. JSON makes a lightweight alternative to XML-based approaches to data serialization, like XML Schema. The JSON web site links to implementations in many languages, and I refer you to that site rather than mentioning a JSON library for every language.