JSON

Many message formats have been defined for exchanging structured data: ASN, DCE RPC, ONC RPC, IIOP, DCOM IDL, , ... Many alphabets have been defined, on which new languages (message definitions or RPC contracts) were built!

Although XML had its roots in the document centric world (as a successor for SGML), XML gained an immense popularity in the world of structured data. XML was considered a good standard for self-describing messages: no mixed content but tree-structured messages with data only at the leafs of the tree. First DTD's and next XML schema's provided mechanisms to describe the XML messages.

Pushed by HP's eSpeak and XML-RPC, the SOAP protocol triggered the creation of the WS-* stack. But with the rise of AJAX and other Web 2.0 technologies, new alphabets emerge and gain popularity. JSON is one of those new kids on the block.

Rich Internet clients are not limited to HTML but use all sorts of message structures on top of HTTP. With the use of Javascript in the browser, a Javascript friendly protocol eases life. That's what JSON is all about. Apart from JSON, many other protocols such as Adobe AMF pop up (performance comparison, thanks Stephan for the link).

Now, what is the impact for the integration world. Of course, JSON and others will be used for a few A2A and B2B scenario's (although I haven't seen any yet). But many tools will need to extend their XML support not only to REST, but to many other protocols. Organizations will keep one main entry point for all their HTTP traffic. Next to HTML and XML, JSON and others will be added. Therefore, infrastructure will be impacted first, e.g. XML gateways will need to add JSON support change their name from XML gateway ;-)

Standard ways of using JSON are already popping up, e.g. JAX-RS (JSR-311) adopted Jettison for JSON support and includes JSON-XML converter which follows the Badgerfish approach for JSON-XML conversion.

JSON-XML deserves our attention: a widely accepted XML representation for JSON (don't use the word "standard") will allow re-use of transformation logic. But I have some doubts around this Badgerfish JSON-XML conversion. It takes XML as a starting point, e.g. it puts XML namespaces inside JSON which doesn't look nice.

Note: while attending SpringOne, I was caught by surprise when encountering the first use of JSON for a configuration file (for the new Spring container if I remember well)