WiX Toolset

Repository Reorganization

User stories

  • As a WiX developer I can work on a focused subset of the toolset such that I am more productive because there is less code and the development loop is faster.

  • As a WiX developer I can work on a focused subset of the toolset such that I consider the interfaces between independent parts of the toolset.


Today the WiX Toolset is a monolithic repository per major release. This makes it easy to build everything from a single repository. The downside is that you build everything and need everything to build. Since the WiX Toolset functionality spans the breadth of the Windows ecosystem that means you need a lot of tools to build (Windows SDKs, multiple versions of Visual Studio, etc).

There are also large portions of the WiX Toolset that do not change from release to release. That means code is being rebuilt and redistributed even though there is no change. This not only wastes developer time and build machine time but customer installation time.

Finally, NuGet has changed the way that developers share libraries. There is functionality in the WiX Toolset--such as dutil, wcautil, and DTF--that would be more accessible if made available via NuGet.

To modernize the WiX developer experience, this proposal recommends breaking the wix4 monolithic repository into several smaller repositories each focused on an independent part of the WiX Toolset. When considering how to reorgnize the WiX Toolset's repositories it is important to the layers of functionality in the toolset itself:

  1. Libraries - independent functionality the rest of the toolset builds upon. Examples include: dutil, wcautil, DTF, and WixToolset.Data

  2. Burn - the bootstrapper engine and its interfaces

  3. Core - the command-line tools, MSBuild integration, Compiler/Linker/Binder

  4. Votive - WiX Toolset's Visual Studio Extension

  5. WiX Extensions - extensions to the WiX Toolset. Examples include: WixIisExtension, WixNetfxExtension, WixSqlExtension, and others


First and foremost, the libraries in the WiX Toolset are split on interface boundaries. Changes made to a library must take into account the interface and what breaking changes might occur. Today it is too easy to change a library in the WiX Toolset and "fix up" the Core without considering dependents outside of the WiX Toolset itself. With the libraries separated, breaking changes will be easier to detect.

Second, library repositories must be independent from each other so a single set of functionality is published by a respository. For example, dutil and wcautil libraries live in separate respositories so changes to wcautil do not cause dutil to be published.

Here are the proposed Library repositories:

  • Dutil - publishes dutil.lib for all supported versions of Visual Studio via a NuGet package: WixToolset.Dutil. Additionally, deputil files will be moved into dutil and there will be no deputil.lib in the future.

  • Wcautil - publishes wcautil.lib for all supported versions of Visual Studio via a NuGet package: WixToolset.Wcautil

  • Balutil - publishes balutil.lib for all supported versions of Visual Studio via a NuGet package: WixToolset.Balutil

  • Dtf.Compression - publishes the Compression assemblies in Dtf via NuGet packages: WixToolset.Dtf.Compression, WixToolset.Dtf.Compression.Cab, WixToolset.Dtf.Compression.Zip

  • Dtf.Resources - publishes the Resources assembly in Dtf via NuGet package: WixToolset.Dtf.Resources

  • Dtf.WindowsInstaller - publishes the WindowsInstaller assemblies in Dtf via NuGet packages: WixToolset.Dtf.WindowsInstaller, WixToolset.Dtf.WindowsInstaller.Package

  • Data - publishes the WixToolset.Data assembly via NuGet package: WixToolset.Data

  • Extensibility - publishes the WixToolset.Extensibility assembly via NuGet package: WixToolset.Extensibility


The Burn engine and its interfaces (IBootstrapperEngine and IBootstrapperApplication) are separated into an independent repository to be shared by both the Core, Balutil and the WixBalExtension repositories.

This repository publishes burnstub.exe for the Core and the NuGet package: WixToolset.Bootstrapper.Interfaces.


The Core is where the bulk of WiX Toolset development takes place. This repository includes all command-line tools, MSBuild integration (including DTF's custom action integration) and, of course, wix.dll.

This respository is responsible for building and publishing the bundle and NuGet package for the WiX Toolset.


The WiX Toolset's Visual Studio Extension, Votive, is separated from the Core and distributed via the Visual Studio Marketplace. Doing so dramatically improves the WiX Toolset's installation speed. Additionally, developers can install Votive without installing the WiX Toolset and .sln's with .wixproj's will load cleanly.

This respository produces a VSIX for each version of Visual Studio supported, namely: 2010, 2012, 2013, 2015 and 2017.

WiX Extensions

Separating each WiX Extension into its own repository provides several benefits. First, WiX Extensions are already very independent and would benefit from a tight developer loop. Second, developers do not need to be overwhelmed with the full WiX build process to work on a particular WiX Extension. Finally, a WiX Extension release schedule would no longer be tied to the Core release schedule.

When the Core bundle is created it will include the "last known good" of each WiX Extension via an MSI package. WiX Extension repositories will also each output an add-on bundle to the Core bundle that installs the WiX Extension's MSI package. This allows WiX Extensions to upgrade the "last know good" provided by the Core.


  • While this reorganization optimizes for working within a focused subset of the WiX Toolset, it does make fixing cross cutting issues much more difficult. This is partly the goal (to create friction to changing public interfaces) but we must recognize that it will be required at times. So work will need to be done to help

  • There are several ways to slice the DTF repositories. For example, all of the respositories could be in a single Dtf repository or the respository could be broken down further (for example, Dtf.Compression, Dtf.Compression.Cab and Dtf.Compression.Zip). The current proposal attempts to strike a balance between respository explosion and complete isolation of functionality.

  • It is enticing to break out DTF's custom action host into its own respository since it never changes and the only consumer is the Core. Still considering if that is reasonable.

  • The .NET Framework team recently consolidated their CoreFX repositories into a single respository. That would suggest reorganizing our single repository into many would be the wrong thing to do. We should keep in mind their "Primary reasons for the changes" and make sure we do not repeat those mistakes. However, this proposal focuses on reorganizing the WiX Toolset's repositories based on layers. Our dependency graph has never looked this bad.

See Also