Getting to the .NET Core of Things


Microsoft’s tech stack (for various types of applications) has been .NET for over 15 years now. For the most part of those 15 years, Microsoft has exclusively focussed on proprietary, Windows-only software. In recent years Microsoft shifted to open source and cross platform solutions in many areas, including .NET. With that, the newest incarnation of .NET is .NET Core, which is completely open source and available across various platforms.

How .NET traditionally worked

Let’s first investigate how .NET in general works, with the pre-.NET Core context in mind.


The best way to start explaining about the “new” .NET situation is by building a glossary.

.NET Standard

The .NET Standard API specification for .NET Implementations has different versions. The code and documentation can be found on GitHub, which also shows which implementations conform to each version of .NET Standard. Here’s a trimmed down version of the current overview:

namespace System {+    public sealed class StackOverflowException : SystemException {+        public StackOverflowException();+        public StackOverflowException(string message);+        public StackOverflowException(string message, Exception innerException);+    }}

.NET Core

This is where things get cross-platform! You can download the SDK for Windows, various Linux distributions (e.g. RHEL, Ubuntu and Mint, SUSE), and Mac OSX. The SDK contains both the CoreCLR (runtime) to run applications, as well as the tools needed to create and build applications.

  1. Create a folder “hellow” and cd into it;
  2. Execute dotnet new console, which a scaffolded application;
  3. Execute dotnet run.
  • Visual Studio is still probably the best experience on a Windows machine.
  • VS Code is available on Windows, Mac, and Linux, offering a pretty light-weight IDE.
  • JetBrains Rider is an Intellij-like IDE for .NET development, available on Windows, Mac, and Linux.

Wrapping Up

Microsoft is changing up their game. Although the traditional .NET Framework is here to stay, the new .NET Core framework is the future. They are both .NET Implementations and yes: they have overlap (as defined by .NET Standard). But you can safely bet on the fact that .NET Core and .NET Standard are going to get focus forward.

Appendix A: Bonus Topics

There are plenty more in-depth and advanced topics. Here’s a quick list of particularly interesting ones you could further pursue:

  • Docker and .NET Core go very well together. The official docs on that should be a good starting point.
  • EF Core (Entity Framework Core) gets a lot of attention too. EF is Microsoft’s ORM framework, and it has its own dedicated (sub)site with more info.
  • UWP (Universal Windows Platform) for creating Windows Store apps that could be cross platform (including things like Xbox, Windows Phone, HoloLens, etc) will also likely conform to .NET Standard. Check the main UWP docs for further info.
  • Roslyn is the code name for the open-source compilers for .NET languages. The best starting point for more details is the Roslyn Github repo.
  • .NET Native will allow you to compile your .NET code not to IL (bytecode), but to platform-specific native code. Check the official docs for more info.

Appendix B: Obsolete Terminology

Here’s a short list of (currently) prominent terms that I consider to be obsolete, along with their definition (and the source of that definition, if applicable).

  • DNX (Dotnet Execution Runtime), DNVM (script for obtaining DNX) and DNU (Dotnet Developer Utility) were part of older Release Candidates of .NET Core. The features have mostly been moved to the .NET Core CLI. See the Microsoft docs for more info.
  • project.json was meant to be the new project system, but instead Microsoft decided to move back to csproj files with some new features. Read more on these Microsoft docs pages.
  • PCL (Portable Class Library) was an earlier attempt to help library authors create code that could be reused across various fameworks and platforms. The best reference I could find is these docs from Microsoft. In light of .NET Core you can easily forget about it though, unless you need to convert a PCL project to .NET Core.
  • vNext (which at some point was also called ASP.NET 5) can best be seen as a working title of the next .NET Framework version (the one for Windows only), but has been dropped entirely. About the only semi-sensible reference left is on Stack Overflow.
  • ASP Classic is not really an obsolete term, but rather obsolete technology. The latest stable release was from around the year 2000. It has nothing to do with .NET or the various ASP.NET application frameworks. Wikipedia has a quick history recap if you want it.




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