This post demonstrates how to get a an OWIN/Katana sample app running on Heroku. It uses the Mono buildpack that I’ve already covered on the blog. As far as I can determine, Heroku is the only public platform where you can conveniently prototype and share OWIN apps running on Katana.

OWIN and Katana

OWIN is the Open Web Interface for .NET, a specification for how apps and frameworks should interact with servers that host them. It’s very much like Ruby Rack, only for .NET. By decoupling apps from web servers, it should become much easier to write portable middleware that can be reused between apps and  frameworks. There’ already a ton of good OWIN stuff on NuGet.

Katana is a set of components (including a web server) built by Microsoft and others that conforms to the OWIN spec. Here’s a great overview write-up about Katana. There are other OWIN compliant servers (like Kayak) and hopefully more will show up.

OWIN and Microsoft adopting OWIN is pretty exciting: It will make writing good .NET web apps easier and it’s going to free .NET web developers from their historical over-reliance on the IIS web server. With IIS out of the picture, hosting apps on Mono and on open platforms like Heroku will be much easier.

Getting started

The sample demoed here is an expanded version K. Scott Allen’s sample. Here’s how to get started:

1. Open Visual Studio and Create a C# Console Application and enable NuGet package restore. I used Visual Studio 2012 and named the app KatanaTest.
2. Install OWIN NuGet packages

   install-package Microsoft.Owin.Hosting -IncludePreRelease
   install-package Microsoft.Owin.Host.HttpListener –IncludePreRelease
   install-package Microsoft.Owin.Diagnostics –IncludePreRelease
   install-package Owin.Extensions -IncludePrerelease

3. Add a class that configures the app to just display the Katana sample page.
4. Add a Main entry point that listens for HTTP on a port specified as a command line argument and waits for ctrl+c to exit.
5. Add a Procfile that tells Heroku how to start the app, passing in the $PORT as an argument.
6. Fix casing bug and restore command to make project build on Heroku (these will hopefully soon be fixed in NuGet). (Fixed in latest buildpack version)
7. Deploy to Heroku:

       $ heroku create
       $ heroku config:add BUILDPACK_URL=https://github.com/friism/heroku-buildpack-mono/
       $ git push heroku master

Check out the sample running live on Heroku. The sample project is available on GitHub.