There are a lot of changes currently going on in the Microsoft development work in general and with .NET specifically, so I wanted to write some articles to look at one area in particular and that is ASP.NET. The changes going on with ASP.NET are pretty radical and exactly what is happening can be a little confusing. This is only made worse by a recent name change for the next version of ASP.NET.

Last year Microsoft announced a new vesion of ASP.NET that they called ASP.NET 5.0. Most updates to the .NET components are incremental updates that build on what came before. ASP.NET 5.0 on the other hand is a total re-engineering of ASP.NET from the ground up. To meet some of the design goals of the new version Microsoft has dropped, at least for now, some features from ASP.NET. For this reason Microsoft recently changed the name from ASP.NET 5.0 to ASP.NET Core 1.0. The new version is only at RC1 at the time this was written, but when it is released there will be two release version of ASP.NET, the full featured 4.6, and the new Core 1.0.

So what is different in ASP.NET Core 1.0. Here are some of the major bullet points.

Cross Platform Execution - The word “Core” in the new name is a reference to .NET Core which is a new version of the .NET Framework designed from the ground up to run on Windows, Mac and Linux. The new version of ASP.NET can run on either the existing 4.6 Framework, or on top of the new Core framework which allows it to be hosted on non-Windows servers. Since a lot of the things in the framework need to be updated to work cross platform, Core currently supports a lot fewer namespaces then the 4.6 framework.

Cross Platform Development - Besides running cross platform, .NET Core applications can be developed on Windows, Mac and Linux. Windows development can be done in Visual Studio as before, and all three environments can use command line tools and the new cross platform Visual Studio Code editor.

New Runtime - ASP.NET Core 1 uses a new run time called DNX. DNX is not only a key component of the cross platform support but also provides all the tools needed to build apps on each platform. DNX contains command line tools used to manage the installed frameworks, manage dependencies and execute .NET core applications.

Modular - Core 1.0 has been designed to be highly modular, you only bring in the features you need using NuGet.  A bare bones ASP.NET Core 1.0 application cannot do much beyond handing  HTTP requests and repsonses. If you want static file handling, there is a module for that, logging is another module, MVC yet another, etc.

Performance - The new version of ASP.NET has received a lot of performance optimizations. A lot of this performance comes from the modular nature. Since the HTTP pipeline only needs to contain what you absolutely need for your app you can have a much leaner and faster pipeline. Even with full MVC enabled Core 1.0 provides better request performance than the previous version.

Web Server - The previous versions of ASP.NET were closely tied to IIS, your application actually ran as a processes within IIS. To allow for cross platform support ASP.NET Core 1 breaks the dependancy and runs your application is a seperate process. On Windows IIS can still used, but is can serve as just a reverse proxy that passes requests back and forth to ASP.NET via the open source Kestrel web server of the more lightweight WebListener. Kestrel can also be used to run cross platform.

Open Source - ASP.NET Core 1 is open source, you can download the current source on https://github.com/aspnet. Besides being open source, the whole development process has been very open. You can watch the weekly update videos from the development team here, https://live.asp.net/.

In my next post we will take a look at some actual ASP.NET Core 1 code.