Goodbye project.json

msbuild edit

This is a follow-up about project.json being abandoned in favour of msbuild

Why project.json (speculations)?

  • Because at the time the ASP.NET team worked on this, MSBuild was not open-source nor cross platform
  • MSBuild is a XML file that is laborious to edit, too verbose and usually not friendly in the eyes of a developer (at least, a bit more laborious to edit/view than a JSON file)
  • MSBuild and NuGet were poorly integrated (NuGet was polluting project references, references were duplicated/stored in a separate package.config file...etc., you had to specify a nuspec file on the side to package something from a csproj)
  • NuGet dependencies were not transitive, so we had to list dependencies explicitly
  • MSBuild was not able to easily target multiple platforms (you can, but you have to duplicate sln/csproj in order to achieve it correctly, very laborious)
  • "Dude, I don't want to maintain a list of files to build my app" (a js dev talking)
  • JSON is widely used in node.js/web techs, so let's use a format that sounds familiar to web devs
  • JSON felt more "data-oriented" than the freaking/bizarre msbuild model (some declaratives, some processes with an awful XML declarative language...etc.)

What went wrong with project.json?

The problem is that project.json quickly had to replicate many msbuild project behaviours https://github.com/aspnet/Home/wiki/Project.json-file (things like configurations, build targets, compilation flags, build commands...etc.) and well, you don't want to rebuild a build system, so at some point, everything had to go back to a well established build system (hint: msbuild) in order to build things efficiently (track file dependencies, don't compile things that are not necessary, add build conditions... etc.)

Things became worse and a bit more weird with xproj that acted as a bridge between the msbuild system and pseudo-build-system project.json, still project.json (and the underlying dnx ASP.NET vnext build system) was nowhere a build-system

So back to msbuild?

While not ideal, it is easier to adapt msbuild to cover the missing bits, mainly:

  • integrate the project.json dependencies part directly into a csproj is easy to do
  • automate cross-platform compilation
  • automate NuGet package creation

Incidentally, I wrote an article almost 2 years ago that talked a little bit about this in "Packages vNext: Power-up our .NET Builds".

So I could not be more happy to see project.json being phased out. Back to a unified model will be way more sane and simpler to manage!