A Comparison of TFS vs Subversion for Open Source Projects

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We’ve been having an internal debate within the Subtext mailing list over the merits of SourceForge vs Google Code Project Hosting vs Codeplex. Much of the discussion hinges around the benefits of Subversion for Open Source projects when compared to Team Foundation System (TFS).

Before I begin, I do not mean for this to devolve into a religious argument. This is merely my critique from the perspective of running an Open Source project. I personally think both are fine products and both probably work equally well in the corporate environment.

TFS Advantages

  • Easy of use. For developers with a background in using Visual Source Safe or Sourcegear Vault, the interface into TFS will be familiar. Subversion requires more of a learning curve for these developers, though this is mitigated by my suspicion that a large percentage of Open Source developers tend to use CVS and SVN already. 
  • Work Item integration is sweet. I’ve been contributing some code to the Subsonic project and I actually love the work item integration in VS.NET. It’s pretty nice to be able to review and close work items while working on the code.
  • Shelving is great. Certainly nothing stops you from doing something like this in Subversion by using conventions, but I like the ~~syntactic~~ workflow sugar this provides.

Subversion Advantages

  • Anonymous access. Users who want to look at the code, view the change history of the code, and update their local code to the latest version can do so form the convenience of their favorite Subversion client. This is much more cumbersome with TFS.
  • Patch Submission. This goes hand in hand with anonymous access. Users without commit access can have Subversion generate patch files consisting of their changes and submit these files. This makes it really easy for the casual contributor to quickly submit a patch as well as makes it easy for the Open Source development team to apply contributions to the source. This is a huge benefit to the project. Unfortunately with CodePlex, you either give commit access or you don’t. If you don’t, it’s a pain for users to submit patches and a pain for the project team to apply patches. Just ask Rob Conery what happens if you give commit access too freely.
  • Offline Support. Regardless of what Jeff says, offline mode does matter for many applications. For example, sometimes I have to connect to an obnoxious VPN that destroys my general internet connectivity. It’s nice to be able to connect, get latest, disconnect, work, connect, commit changes, disconnect. Try that with TFS.

Again, as source control systems, I believe they are both great systems. But for the needs of an open source project, I feel that Subversion has advantages. As far as I understand, TFS was designed as an enterprise source control system. However, the needs of the enterprise are often different from the needs of an Open Source team.

Subversion, itself open source, was used during its own development (when it became stable enough). So it is well suited to open source development.

If Codeplex supported Subversion, I would probably want to move Subtext over in a heartbeat. If you feel the same way I do, please vote for the work item entitled Subversion Support (SVN).

It looks like a lot of people would like to see this as well as it is the top vote getter on the Codeplex work item site.

And before you rail on me asking, Why Microsoft would ever consider such a move? Isn't Codeplex a showcase for TFS and Microsoft Technology Open Source projects?

A member of the Codeplex team informed me that Codeplex is the home for any Open Source project - on any and all platforms. In fact, they do now host a few non-Microsoft projects. Of course their dependency on TFS does naturally limit the types of projects that would host there.

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