Software versioning, Apache strategy

In the last few weeks, my job is to make my mates job easier. I have been installing a simple Continuous Integration System, Maven plugins and Eclipse add-ons.

I can't share a lot of this information until I have learned it properly. I would want to show that with good examples and error-solving snippets.

What I can tell you right now is the versioning system of apache, I liked it too much because it is simply, easy to learn and use, easy to learn, teach, memorize..

http://apr.apache.org/versioning.html

This system is used by lots of other software companies, let's explain in few words:

Let's take a random version: 3.2.1, for example.

You resolve a bug, and make a patch for your clients, increment the third number.
You create a feature, but you don't change any of previously existent functionality, increment the second number.
You change a functionality, breaking the contract of your previous versions. increment the first number.


The result might be the following.

Previous version: 3.2.1
You upgrade to 3.2.2
It is supposed to be fully compatible

Previous version: 3.2.1
You downgrade to 3.2.0
It is supposed to be fully compatible. Obviously, it could work worse, there is an absent patch.

Previous version: 3.2.1
You upgrade to 3.3.1 (or 3.3.0)
 It is supposed to be fully compatible with the same configuration.

Previous version: 3.2.1
You downgrade to 3.1.1 (or 3.1.x)
Compatibility with prior minor versions is not guaranteed. *

Previous version: 3.2.1
You upgrade to 4.2.1 (or 4.x.x)
Compatibility with different major versions is not guaranteed.

Previous version: 3.2.1
You downgrade to 2.2.1 (or 2.x.x)
Compatibility with different major versions is not guaranteed. *

* The best explanation for this phenomenon is, lets say, 3.2.1 introduced two lines in configuration files, which are parsed with a certain pattern. It could be possible that previous version was not able to parse your configuration with those unknown new lines.

A good coherent versioning system will give free information to your team and customers about how compatible your versions are between them. Avoid marketing formulas for your version, at least, inside your I.T. department. You could also use standard tools for autoincrement versions, like Maven (sooooon).

See you at @anavarro_prof twitter ;)