Version Control – SVN vs. VSS vs. Git

Someone asked a question about version control software on Experts Exchange recently, and my answer turned into potential blog material:

Version Control Concepts
I’ve used Subversion (SVN), Visual SourceSafe (VSS), and Git. The concepts are all the same, though. Version control basically means that all of your application files are “checked in” to a big container (called a repository) that sits in some central location (usually a server) that your developers can all access.

To work on the application, you usually “check out” the project from the repository. This basically downloads the files from the repository onto your local computer so you can edit them and so on. Usually, developers have their own testing environment on their local computer so they can quickly test their changes. After a developer has finished with his/her changes, the dev “commits” the files back to the repository. This usually does not remove the files from the developer’s machine – it just copies the changes back to the server. The server receives the files, figures out what’s new and what’s changed, and then applies those changes to the repository.

The version control part of it comes into the picture here. The server keeps track of each change of the file (when it’s committed). So when you start with a file that just has “abc” in it and you edit the file, change it to “abcdef” and commit it back to the server, the server now knows that the LATEST version of the file has “abcdef” but if you ever need a previous version (often called a “revision”), then you can request it from the server.

Using Version Control for Software Development Lifecycle
What I often do for smaller projects is have one repository. I then set up my production, testing, and development environments all as working copies (meaning that each is basically a “checked out” version of the application). The working copies don’t update themselves automatically, so each environment will stay at its particular revision until you tell it to update.

So if I start out at revision #1, all 3 of my environments are also at revision #1. I then make changes and stuff on my development machine and commit the changes (let’s say I do this a few times unti l get to revision 4 or something). Now my environments look like:

Production: Revision #1
Testing: Revision #1
Development: Revision #4
Central Server / Repository: Latest Revision is #4

When I’m ready to officially test, I go to the Testing server and simply use the appropriate tools to check out the files for Revision #4. (Side note: you usually don’t have to remember revision numbers. You can often just tell the tool to check out the latest revision, whatever it is. But if you have a lot of developers or something, you may want to specify the revision in case other people are committing things that should not be in the official testing environment). Now my environments look like:

Production: Revision #1
Testing: Revision #4
Development: Revision #4
Central Server / Repository: Latest Revision is #4

Let’s say revision #4 tested successfully, and is now considered ready for production. At this point, I go to the Production environment, and use the version control tools to update to Revision #4. (I always specify the revision for production releases, just to be extra certain I’m not pushing anything that should not be pushed).

Now all environments are at Revision #4, and the lifecycle is complete.

That’s basically how I use version control systems to control new version releases of my applications.

Now that I’ve offered a basic explanation of the idea of version control, here are some specifics:

Visual SourceSafe – Not Good
I started using Visual SourceSafe (VSS). About 4 months into a non-.NET project, we ditched it because it was occasionally corrupting files. It seems okay for .NET projects, but I wouldn’t trust it on anything else.

Subversion – Better, Friendlier
I then used SVN, and it worked decently well for the most part. It has 3 downsides, in my opinion:

#1. After about a year, I noticed that there was a significant decrease in speed when checking for updated files or committing updated files.

#2. SVN creates a .svn folder in each folder of your application in order to track the files. Normally, this doesn’t bother me, but it did significantly increase the number of files in the system (the .svn folder contains a structure that has separate files that contain information about each file that is tracked).

#3. SVN is not very smart about merging branches of development. This may not be an issue for you if you only have a couple developers or if you don’t really want to use branches at all.

One upside is that there are a lot of nice tools you can use with SVN, like TortoiseSVN. Many of those tools make the process pretty simple (1 or 2 clicks).

Git – Best, Not as Friendly
Git is what I’m using now for most of my projects. I use it because it is much faster than SVN in many respects (especially when you have a lot of small files), it only needs one .git folder in the top folder of each application to track the entire app (instead of the many .svn folders), and it is much better at merging and branching (which is what I use for more complicated projects).

The only two downsides of Git that I’ve found are:
#1. it is not as immediately user-friendly as SVN. There IS a TortoiseGit program that is supposed to simulate the popular TortoiseSVN program, but I have not tried it yet. I use a tool that gives me a Linux-like shell on Windows and I use that. Once you’re used to it, it’s just about as fast (if not faster) than the GUI tools.

#2. there are some SVN commands that were nice that have not yet been introduced to Git (some analysis tools, mainly). This is not a big deal, though, because of Git’s other strengths that let me easily work around this.

Ultimately, I would go with SVN or Git. Maybe use SVN to start out and get used to the whole idea, and then upgrade to Git when you recognize the differences. They are both free, open-source products (with free, open-source client tools, too), so you’re not really going to spend any money on either one.