Incremental Builds with TFS

A very handy TFS feature is kind of well hidden in the settings. The setting is so "tiny" that I did not find it for a long time. But first things first.

The task: set up a team build that compiles only those assemblies that have been modified since the last build. You can call this an incremental build.

The whole magic is the "Clean Workspace" parameter in the build definitions process tab. Here one can choose how the build handles its workspace. You have three choices:

1. All: Delete Sources & Binaries, then get all and build all. This is a complete rebuild. This is the default
2. Outputs: Delete the binaries but keep the sources. Gets only the sources that have changed (incremental get). Recompiles all the sources so you get a full set of binaries.
3. None: Delete nothing. Gets only the sources that have changed and rebuilds only assemblies that have changed. 

Option three is the one that does the trick. If you trigger a build, than change something and trigger another build, your drop location will hold two folders. You will see all the files in both folders but dont be disappointed. All files are moved to the drop location, but mind the changed date: they are all different.

This way you can figure out easily what has acutally changed. This comes in handy if you want to ship hotfixes that only contain files that have really changed to keep installing the hotfix quick.

Have a nice build ;-)

Tobias.