With MOSS 2007, I often got asked what order do I install these solution packages in.  Oftentimes, it was critical that they get installed in a particular order.  With features, we have had the ability to set dependencies, but we really didn’t have anything like that for solution packages.  Well, I haven’t heard people talking about this new feature yet, but we can in fact set solution dependencies in the manifest.xml file.

The way it works is that it checks to see if a dependent solution has already been deployed on your farm (or site collection for sandbox solutions).  However, it won’t chain deploy child solutions for you like you can do with hidden dependent features.  It does this check when you attempt to deploy the feature (not when you add it).  It also won’t remove a parent solution should you remove any of its dependent child solutions.  Solution dependencies will also work between sandbox and farm solutions.  Here is what the XML looks like that you will put in your manifest file.

The last thing I’ll point out is there is no Visual Studio Designer support, but you can get to the XML through the package editor and add the necessary XML pretty easily.