TFS Build 2015 … and versioning!

August 24, 2015

Lately I got some time to play a bit more with the new build system which was released with TFS 2015 and which is also available for Visual Studio Online. The new build system was in the beginning announced as build vNext, but now with the release of TFS 2015, it’s safe to call it Team Foundation Build 2015 (TFBuild 2015) while the “old” build system can be referred to as the xaml (workflow) build system. Colin Dembovsky has a great post why you should switch to the new build sytem.

In the last years, I had to implement a lot of customizations into the xaml build system and I became very productive with the workflow activities. Along the way I developed a number of generic activities which I could reuse for other assignments and I really knew my way around in the build workflow. In many cases, the TFS Build Extensions were used to not reinvent the wheel. So, in the first phase I was a bit sceptic about the rise of yet another build system, but I clearly saw some interesting advantages which are explained in the post by Colin. One disadvantage of the xaml build system is the steep learning curve to master the customization process and also the deployment mechanism to refresh the TFS build controller(s). But like I experienced, once you got there, you were able to integrate very powerful customizations into the build process. Anyway, the “old” build system won’t disappear and you can still rely on this functionality for quite some time in the future, but I recommend to have a good look at the new build system and use it for your new/future build definitions.

In this post I want to share how I integrated a common activity in the build process: Versioning. With the available build steps it has become extremely simple to hook your own scripts into the build process. In your scripts you will have access to some predefined build variables.

In my previous blogpost I wrote about adopting a Global .NET Versioning Strategy and the existence of a third (optional) version attribute: AssemblyInformationalVersion. Let’s use this strategy to add versioning to a sample Fabrikam software application.

My build definition:


In the screenshot above you will see that I launch a powershell script (PreBuild.ps1) before building the solution and I pass one argument productVersion to the script. The powershell script will do the magic in the background to replace all versioning values for AssemblyVersion, AssemblyFileVersion and AssemblyInformationalVersion in the Assembly Info files, based on this product version. The product version will be passed as a whole to the AssemblyVersion and the AssemblyInformationalVersion attributes. The AssemblyFileVersion will be replaced with a full version number which will consist of the major and minor version number of the product version, a Julian based date and an incremental build number.


Assembly File Version = 1.0.15236.3

  • 1 => taken from “Major” product version
  • 0 => taken from “Minor” product version
  • 15236 => generated by build process: “15” = year 2015, “236” = day of year 2015
  • 3 => third build, run on day 236 in year 2015

Looking at the assembly details of a custom built Fabrikam assembly now reveals correct meta data:


I also modified the build number format to have some more version information displayed in the build run.



I added a gist at GitHub to share the powershell script. Note that the script has been used for experimentation and may not be ready to be used for production. it certainly lacks some proper validation and error-handling. Use at your own risk.

Also have a look at some similar inspiring blog posts about versioning TFS Builds which helped me to develop the powershell script that works for my scenario.

Global .NET Versioning Strategy – AssemblyInformationalVersion

August 24, 2015

Ever heard of a third (optional) versioning attribute in the AssemblyInfo files: AssemblyInformationalVersion. No? Please read!

Without a methodical (assembly) version numbering strategy, the ability to determine what changes were included in which version is lost. In my opinion, you always need to know exactly which source files went into which build and which version of the sofware is currently deployed in a specific environment. A random version numbering system creates confusion and will soon or later cause deployment risks. It will become a nightmare to fetch the exact source files to reproduce a bug from production.

All versioning of .NET assemblies that use the common language runtime is done at the assembly level. The specific version of an assembly and the versions of dependent assemblies are recorded in the assembly’s manifest. The default version policy for the runtime is that applications run only with the versions they were built and tested with, unless overridden by explicit version policy in configuration files.

Each .NET project has an AssemblyInfo file which contains an AssemblyVersion attribute and an AssemblyFileVersion attribute.

  • AssemblyVersion: this is the version number used by the .NET framework during build and at runtime to locate, link and load the assemblies. When you add a reference to any assembly in your project, it is this version number which gets embedded. At runtime, the CLR looks for assembly with this version number to load. But remember this version is used along with name, public key token and culture information only if the assemblies are strong-named signed. If assemblies are not strong-named signed, only file names are used for loading.
  • AssemblyFileVersion: This is the version number given to a file as in file system. It is displayed by Windows Explorer. It’s never used by .NET framework or runtime for referencing.

But what about this difference between AssemblyVersion and AssemblyFileVersion? Many times, I see that the same version is applied to both attributes … but why are these two (different) attributes provided by the .NET Framework? The AssemblyVersion should be the public version of an entire software application, while the AssemblyFileVersion is more the version of a specific component which may only be a small part of the entire application. The AssemblyFileVersion is the best place to put extra build version information which can be important for patching individual components of a software application.

Please follow the Semantic Versioning recommendations to dictate how the AssemblyVersion should be assigned and incremented. For the AssemblyFileVersion, I tend to include specific build information. Often, you will need to build (and test) a number of time a specific SemVer version of your software.

For example: release 1 of a software application could have the AssemblyVersion set to 1.0.0 (all components), while the AssemblyFileVersion of the individual components could be set to 1.0.15234.2 which refers to a unique build number of the build system and is linked to a particular date and a revision: “15” = year 2015; “234” = day number in 2015; “2” = second build processed that day. This also allows to later patch individual components in production with a similar AssemblyVersion (1.0.0), but a different AssemblyFileVersion (1.0.15235.1).

So, let’s try to apply this to a test project in Visual Studio and see the assembly details after building the project …


Now you should be confused! Why does the Product Version display the AssemblyFileVersion and where’s the AssemblyVersion? The problem here is that a new Visual Studio project doesn’t include a third version attribute AssemblyInformationalVersion which is intended to represent the public version of your entire software application. Note that the CLR doesn’t care about this third (optional) version attribute. In short, the same Semantic Versioning rules of AssemblyVersion should be applied to AssemblyInformationalVersion.


Aha! This looks much better right? Now it’s also easy to extract this metadata from your deployed assemblies and this information can be nicely listed in the about box of your software. The only issue with this approach is that the AssemblyFileVersion doesn’t include the “patch” number (Semantic Versioning) of the AssemblyVersion, but this can be ignored with the fact that the AssemblyFileVersion will be unique and can be linked to a unique build run in the build system. This way of working is my personal interpretation of how versioning can be properly applied in complex software applications and doesn’t reflect official guidelines from Microsoft. My goal here is to make software developers aware of the potential risks of not having a clear versioning strategy.

Now, forget about manually setting version information in the AssemblyInfo files and never ever release software from a local Visual Studio build. In a streamlined build process, generating unique build and version numbers are centrally coordinated. For effective troubleshooting and traceability, it’s imperative that the generated assemblies are stamped with a unique identifier that can be easily traced back to a system build number.

In a next post I will talk about how you can achieve this global .NET versioning strategy with the new build system in TFS 2015.