Should the enterprise standardize on JSON or XML as their lingua franca for Web 2.0 integration? Or should they use both as best fits the application?The decision impacts more than just integration – it resounds across the entire infrastructure and impacts everything from security to performance to availability of those applications.

One of the things a developer may or may not have control over when building enterprise applications is the format of the data used to communicate (integrate) with other applications. image Increasingly services external to the enterprise are very Web 2.0 in that they provide HTTP-based APIs for integration that exchange data in one of a couple of standard formats: XML and JSON. While RSS and ATOM are also seen in APIs as options, these are generally used only when the data being presented is frequently updated and of a “listing” style nature. XML and JSON are used to deliver more complex structures that do not fit well in to the paradigm described by RSS and ATOM formatted information. Increasingly libraries or toolkits are used to build interactive Web 2.0 style applications – XAJAX, SAJAX, Dojo, Prototype, script.aculo.us – and these, too, generally default to XML or JSON, though other formats are often supported as well.

So as you’re building out that Web 2.0 style application and thinking about the API you’re going to offer to make it easier for partners/customers/other departments to handle integration with their Web 2.0 style applications – or even thinking about the way in which data will be exchanged with the client (browser) - you need to think carefully about the choice you’re making. There are pros and cons to both JSON and XML, and the choice has implications outside the confines of application development in your organization.

The debate on which is “best” or “optimal” is far from over, and it’s likely to eclipse – for developers anyway – the religious-style wars over the choice of browser. Even mainstream technology coverage is taking an interest in the subject. A recent piece from C|NET on “NoSQL and the future of cloud databases” says “Mapping object data to JSON, a JavaScript data interchange format, is far less complex. The "schemaless" nature of many of these products is an excellent fit with agile development methodologies.”  Indeed, schemaless data formats are certainly more flexible, but that flexibility has a price that may need to be paid by the rest of the infrastructure.