Through The Ages

If you have documents to worry about, you should also worry about tracking changes made to them

Ever opened an old, oft-edited Word document and wondered what it looked like last week? What about the time you made your own changes, only to find that someone else had overwritten the file with their own version? In the digital chaos we all live in, keeping track of your files-the changes made to them and the person making those changes-is something we all desire, but few actually achieve.

It’s All About Control
To address all these needs and more, we turn to a system that software developers have been using for ages-version control. When you’re working in teams where more than one person needs to edit the same code at a time, you really can’t afford your work to be wiped out by a wayward team member, can you? Version control systems also track every single change made to a file, so if you want to see how the file started out and evolved, you can. The system also gives you a new layer of security-the ability to control access to your documents.

If you’re worried about radical changes to the way you work, fret not. A version control system will fit in quite nicely with the way your company’s files are already organised. Presumably, you have a central file server where all your official documents are stored-this is all the infrastructure you need.

How It Works
The best analogy for a version control system is a public library-the term we’ll be using is repository. Library members (your employees) hunt down the book they want and go to the librarian (the version control software). The librarian then checks their library card, and makes sure that the book in question is indeed available to the member, before letting them check it out. The similarity takes a slight deviation here-when someone returns a file, it will contain changes, and the person checking it in will have to leave a little note indicating the changes made. The version control software then records what changes were made to the file (it’s all binary data ultimately, so this isn’t much of a problem) and stores the new version.

But what if more than one person wants the file? There are three ways that this software can handle the situation: the first is the exclusive check-out, where it denies access to anyone who tries to edit the file once it’s been checked out. This is by far the easiest way to avoid any trouble, and is recommended for most scenarios. However, you might encounter situations where two people need to work on different parts of the file at the same time, and waiting for the file to be available just isn’t an option. If there’s a possibility of this happening often, then you’ll need to opt for a setup where a file can be checked out by multiple users, and all changes made by them will then be merged into the document. If the same parts of the file have been edited by more than one person, the software asks for your intervention to determine whose change to accept or reject.

All this happens in a centralised system; for teams spread out over many cities or countries, a concept called Distributed Version Control comes into play. In such a case, everyone has the full repository, and changes to any document are propagated to everyone. This way, everyone always has the latest copy of the repository, without having to demand it from the server, as in the former two cases. That last bit is purely academic, unless your needs have something in common with those of the Linux kernel, whose developers use a distributed version control software called GIT.

Subversion is most comfortable running as an Apache module on a Linux server. It can also run as a separate Linux daemon, and if you have a Windows server, you can set it to run as a service. Once you’ve set up a repository, there are a lot of ways to access it. When it’s running as an Apache module, you can access your Subversion repository using the WebDAV (Web Distributed Authoring and Versioning) protocol-you can set it up in just a few clicks in Windows in My Network Places. Just add a new Network Place, put in the HTTP address of the Subversion repository, and it behaves like a regular folder!

If you choose not to use the Apache module, or if your server is running Windows, you can run “svnserve”-the Subversion server-which uses its own protocol for access to the repository. Naturally, you’ll need software that uses this protocol on every machine that will access the repository.

Subversion is now the version control software of choice
for nearly all open source software developers today

Enter The Tortoise
TortoiseSVN is another open source project by the same organisation that develops Subversion, and is the recommended Subversion client for Windows PCs. Don’t expect to see a program window or the like: it’s just a shell extension that brings all your repository functions-check out, check in, and so forth-right to your Windows Explorer. Files under version control have their own icon overlays-a green check-mark to indicate that it’s the latest version from the repository, a red exclamation to indicate that you’ve changed the file but haven’t sent it to the repository, and so on.  

TortoiseSVN integrates all your repository functions with Windows Explorer

Reality Check
Like everything else we recommend, do take some time out to analyse your situation before you take the plunge. The most important matter you need to address is whether there are enough “incidences” in your office to warrant the time and effort you need to invest in setting up Subversion-it isn’t as easy a process as one would hope. Add to that the effort of training everyone to use the system.

You’ll also have to take a good long look at the way your data is organised. The idea is the same that we used for the user groups in Mayhem Management last month-make a top level folder structure that represents each of your departments. Once that’s done, try to divide everything into little “projects”-April 2006 Sales can be a project for your sales department, and this will contain all the files relevant to said month’s figures.

After all this, if you decide to go ahead and incorporate Subversion at your office, do write in and tell us about your experiences!