Tuesday 15 November 2011

Merging Visual Studio Setup Projects - At My Wix End

When the Windows Installer first appeared around a decade ago (or even longer?) there was very little tooling around. Microsoft did the usual thing and added some simple support to Visual Studio for it (the .vdproj project type); presumably keeping it simple for fear of raising the ire of another established bunch of software vendors - the InstallShield crowd. In the intervening years it appears to have gained a few extra features, but nothing outstanding. As a server-side guy who has very modest requirements I probably wouldn’t notice where the bells and whistles have been added anyway. All I know is that none of the issues I have come across since day one have ever gone away...

Detected Dependencies Only Acknowledges .DLLs

In a modern project where you have a few .exes and a whole raft of .dlls it’s useful that you only have to add the .exes and Visual Studio will find and add all those .dll dependencies for you. But who doesn’t ship the .pdb files as well*? This means half the files are added as dependencies and the other half I have to go and add manually. In fact I find it easier to just exclude all the detected dependencies and just manually add both the .dll and .pdb; at least then I can see them listed together as a pair in the UI and know I haven’t forgotten anything.

Debug & Release Builds

In the native world there has long been a tradition of having at least two build types - one with debug code in and one optimised for performance. The first is only shipped to testers or may be used by a customer to help diagnose a problem, whereas the latter is what you normally ship to customers on release. The debug build is not just the .exe, but also the entire chain of dependencies as there may be debug/release specific link-time requirements. But the Setup Project doesn’t understand this unless you make it part of your solution and tie it right into your build. Even then any third party dependencies you manually add causes much gnashing of teeth as you try and make the “exclude” flag and any subsequent detected dependencies play nicely together with the build specific settings.

Merging .vdproj Files

But, by far my biggest gripe has always been how merge-unfriendly .vdproj files are. On the face of it, being a text file, you would expect it to be easy to merge changes after branching. That would be so if Visual Studio stopped re-generating the component GUID’s for apparently unknown reasons, or kept the order of things in the file consistent. Even with “move block detection” enabled in WinMerge often all you can see is a sea of moved blocks. One common (and very understandable) mistake developers make is to open the project without the binaries built and add a new file which can cause all the detected dependencies to go AWOL. None of this seems logical and yet time and time again I find myself manually merging the changes back to trunk because the check-in history is impenetrable. Thanks goodness we put effort into our check-in comments.

WiX to the Rescue

WiX itself has been around for many years now and I’ve been keen to try it out and see if it allows me to solve the common problems listed above. Once again for expediency my current project started out with a VS Setup Project, but this time with a definite eye on trying out WiX the moment we got some breathing space or the merging just got too painful. That moment finally arrived and I’m glad we switched; I’m just gutted that I didn’t do the research earlier because it’s an absolute doddle to use! For server-side use where you’re just plonking a bunch of files into a folder and adding a few registry keys it almost couldn’t be easier:-

<?xml version="1.0"?>
<Wix xmlns="
  <Product Id="12345678-1234-. . ." 
           Manufacturer="Chris Oldwood" 
           UpgradeCode="87654321-4321-. . .">

    <Package Compressed="yes"/>

    <Media Id="1" Cabinet="product.cab" 

    <Directory Name="SourceDir" Id="TARGETDIR"> 
      <Directory Name="ProgramFilesFolder"
        <Directory Name="Chris Oldwood" Id="_1"> 
          <Directory Name="vdproj2wix" Id="_2"> 
            <Component Id="_1" Guid="12341234-. . ."> 
              <File Source="vdproj2wix.ps1"/> 
              <File Source="vdproj2wix.html"/> 

<Feature Id="_1" Level="1"> 
      <ComponentRef Id="_1"/> 


The format of the .wxs file is beautifully succinct, easy to diff and merge, and yet it supports many advanced features such as #includes and variables (for injecting build numbers and controlling build types). I’ve only been using it recently and so can’t say what versions 1 & 2 were like but I can’t believe it’s changed that radically. Either way I reckon they’ve got it right now.

Turning a .wxs file into an .msi couldn’t be simpler either which also makes it trivial to integrate into your build process:-

candle vdproj2wix.wxs
if errorlevel 1 exit /b 1

light vdproj2wix.wixobj
if errorlevel 1 exit /b 1

My only gripe (and it is very minor) is with the tool naming. Yes it’s called WiX and so calling the (c)ompiler Candle and the (l)inker Light is cute the first few times but now the add-ons feel the need to carry on the joke which just makes you go WTF? instead.

So does it fix my earlier complaints? Well, so far, yes. I’m doing no more manual shenanigans than I used to and I have something that diffs & merges very nicely. It’s also trivial to inject the build number compared with the ugly VBScript hack I’ve used in the past to modify the actual .msi because the VS way only supports a 3-part version number.

Converting Existing .vdproj Files to .wxs Files

Although as I said earlier the requirements of my current project were very modest I decided to see if I could write a simple script to transform the essence (i.e. the GUID’s & file list) of our .vdproj files into a boiler-plate .wxs file. Not unsurprisingly this turned out to be pretty simple and so I thought I would put together a clean-room version on my web site for others to use in future - vdproj2wix. Naturally I learnt a lot more about the .wxs file format in the process** and it also gave me another excuse to learn more about PowerShell.

If you’re now thinking that this entire post was just an excuse for a shameless plug of a tiny inconsequential script you’d be right - sort of. I also got to vent some long standing anger too which is a bonus.

So long .vdproj file, I can’t say I’m going to miss you...

* OK, in a .Net project there is less need to ship the .pdbs but in a native application they (or some other debug equivalent such as .dbg files) are pretty essential if you ever need to deal with a production issue.

** Curiously the examples in the tutorial that is linked to from the WiX web site have <File> elements with many redundant attributes. You actually only need the Source attribute as a bare minimum.


  1. .vdproj files are truly awful - I was glad to see the back of them too, and Wix provides a nice, straightforward alternative.

    We use InstallAware these days, but it's a bit overkill for small projects.

  2. Thanks to Chris Oldwood! I think InstallAware is better then others.