What are the binary references in WIX? - wix

Question

I've used the dark.exe to create a WXS file from my 'old' Visual Studio 2010 msi file.
When I open the created WXS file, It has binary references on the top of the file that I can't explain. Can somebody tell me about it? And where can I find some documentation about it?
<Binary Id="InstallUtil" SourceFile="C:\Temp\Binary\InstallUtil" />
<Binary Id="MSVBDPCADLL" SourceFile="C:\Temp\Binary\MSVBDPCADLL" />
<Binary Id="VSDNETCFG" SourceFile="C:\Temp\Binary\VSDNETCFG" />
<Binary Id="DefBannerBitmap" SourceFile="C:\Temp\Binary\DefBannerBitmap" />
<Binary Id="UpFldrBtn" SourceFile="C:\Temp\Binary\UpFldrBtn" />
<Binary Id="NewFldrBtn" SourceFile="C:\Temp\Binary\NewFldrBtn" />
The top three are giving me the most questions because I don't where there for and what they do.

Answer 1

Short answer - these files are used in ui dialogs, custom actions, all places where some files are applicable to the functionality of the setup itself, but the product it installs.
In your case, the first three are DLLs used by Visual Studio Setup Projects to perform custom actions - MSI extensibility blocks. The last three are the icons used in UI dialogs later in code.
To get the files themselves, you should use export binaries parameter for Dark.exe.
Now, your options here depend on what you want to achieve. If your task is just upgrade your setup to VS2012, quick and dirty, then use the exported files as they were, it should work.
If, however, you want to do it clean and nice, or you should update your setup with new features, then you will have to rewrite these.
For UI: if your project does not contain custom UI, I suggest switching to WIX UI library - nice and built-in. If you have custom UI, you may extend it, but it is a lot more work. There are visual UI editors for WIX.
For custom actions: custom action is something you use when MSI/WIX abilities do not give you enough. To upgrade these, you should look where these first three binaries are used, and how they are called. Usually, the meaning of custom action may be devised from its name. Then, you have to replace these custom actions with your own (or ready-made by others or WIX team) that do the same. Then you may remove the unused binaries.