Version numbering schemes are probably one of the few things we software engineers have more than sort algorithms. However, there's always room for one more.
While the classic approach of MAJOR.MINOR.PATCH (e.g. 1.8.2) works quite well for libraries or products which are distributed in a broad manner, it is still not as easy as it seems. What is a major change? What a minor? What comes after 1.9? 2.0 or 1.10? There are tons of examples where this classic approach fails, Java being one of the most prominent examples.
One the other hand, this approach is almost perfectly suited for libraries, as the rules are quite obvious here:
- increment minor version for every release (2.4 -> 2.5)
- increment major version when a backward incompatible change was made (2.4 -> 3.0)
- increment the patch level for each update, which only fixed bugs but didn't add functionality (2.4 -> 2.4.1)
Although this approach works quite well, there are two problems with it:
- You need a build server which issues consecutive build numbers
- Without looking at the build server, you cannot tell the age of a release (How much older is BUILD-51 compared to BUILD-52?)
As we don't perform more than one release per week, a version number is always unique. Furthermore these numbers are quite short and easy to remember (compared to full dates like foo-20130527). Still they provide a rough information concerning the release date.
Now as I said, this scheme is not superior over others. It's just a good solution for our problem. Use it if you like it, ignore it otherwise ;-)