Mercurial v Git v Subversion

I need to choose a VCS to embed within a Java application I'm developing. The Java application will interact with the VCS via an API, but the user will also interact with it directly via an Eclipse plugin.

3 candidate VCS have been identified: Mercurial, Git and Subversion. I need to choose one based on the following criteria (in no particular order):

• Java API. This is not 100% necessary, because the application could issue VCS commands via the command-line if no Java API is available. However, an API would obviously be preferable
• Eclipse plugin
• Simplicity. The people using the VCS (indirectly via the application or directly via Eclipse), will be software developers, but probably not the most sophisticated 开发者_运维技巧of the species.
• Licensing. The license must permit to use of the VCS (in the manner described above) in a commercial application

There may be other considerations I've overlooked, I'll update the question if any more spring to mind.

Thanks!

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• Java API: Subversion has bindings for Java, and there is some kind of reimplementation of Mercurial in Java going on (see the dev mailing list).
• Eclipse Plugin: There are plugins that support all three for Eclipse.
• Simplicity: Subversion arguably has a simpler model being centralised. Mercurial tends to be simpler than Git to learn and use, while otherwise being quite close in features.
• Licensing: Git and Mercurial are GPLed, but you can invoke them via the command line with no licensing implications. Subversion uses the Apache license, which is not copyleft.

Now - why not write an interface that abstracts the differences so you can support all three? Mercurial and Git are very similar, so it should be relatively straightforward to at least support these two.

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First of all, I'd scratch out Subversion unless your application has a workflow that works especially well with a centralized VCS. And even then I'd try to use Mercurial or git since svn is just so slow.

Regarding Mercurial (hg) vs Git, I personally would choose git. On one hand, hg is simpler and more intuitive, but git is much faster and has much more mindshare than hg does.

Scriptability might be an issue though. Git is really made to be scriptable from a Unix shell (although it will run on windows with some gnu software installed). Hg has a python interface, but if I recall correctly has some C extensions that will probably make it impossible to use with jython. That said, it looks like there is a third-party git library for Java: http://eclipse.org/jgit/

Regarding licensing, hg and git are both GPLed, but if you shell out to them that shouldn't be an issue. SVN uses an Apache license, so it might win on this front (basically, you can do whatever you want with it).