I’ve always been intrigued by the versioning problem. The versioning problem works like this: you build an API (Application Programming Interface) to get some work done. That API is successful and consumers ask for enhancements to the API. At this point, you have a problem: how do you support everyone who uses the current API while adding enhancements? If you have been down this road, you know that you have to solve the problem early-before success.
The way you handle versioning varies. With compiled code and libraries, you send out a new DLL/Assembly/JAR file and tell folks to convert existing code when they have a chance. With Web services, including SOAP, REST, and just HTTP accessible ones, you have other issues. You typically want a single code base to consume the old and updated messages. Given that many of us are now writing REST services, I talked to InformIT about the need for an article explaining how to version these JSON/XML speaking endpoints. That article is now live and available for your reading at http://www.informit.com/articles/article.aspx?p=1566460.
Karmic Code Monkey 