ASP.NET Core web application

ASP.NET Core is the new Web-development framework developed by Microsoft. The biggest advantages between the previous version of ASP.NET is that it is multi-platform out of the box and is fully open-source. I selected the new ASP.NET Core framework for the development of this sample application because of the multi-platform support. In this post I describe briefly how to create a new ASP.NET Core and the differences between the ASP.NET Framework.

Create a new ASP.NET Core project

There is already a large amount of information available on the web about how to get started with ASP.NET Core so I will not cover this in details again. I will reference to the documentation needed to get started. Click here to view the instruction to install .NET Core on your local machine.

To create a new ASP.NET Core project you can choose between Visual Studio or using yeoman and the command line.
This will create a basic project structure with the necessary configuration and files to start with a web project.

ASP.NET Core Core run-time and frameworks

The new ASP.NET Core framework runs on multiple operation systems out of the box. It leverages this multi-platform support by supporting multiple run-times:

• The CLR is the original Windows run-time developed by Microsoft. It is a non-open source environment but it prove it’s stability more as 14 years in production environments.
• Mono is a multi-platform run-time developed by the community. It is more compatible with the original CLR as CoreCLR. This means that it runs most libraries and frameworks without any problem.
• .NET Core (CoreCLR) is the new multi-platform run-time developed by Microsoft. It is open-source and supports Windows, Mac and Linux. It only supports a subset of the CLR so it is currently not compatible with most CLR libraries.

Each application can run on one or more run-times by specifying the framework(s) it supports. The frameworks are not very well documented for the moment. But at at least following frameworks are available:

• dnx451 is supported by CLR and Mono.
• dnx46 targets the .NET framework 4.6. Although mono support many C#6 features, this framework is currently not (yet) supported.
• dnxcore50 targets only .NET Core (CoreCLR).

Because several libraries I needed for the application does not support Core CLR yet I chose to build and deploy this application in the dnx451 framework. This frameworks is supported on both on the classic CLR as on the Mono run-time.

Project.json

Instead of using a more complicated MS Build file Microsoft decided to put the project definition in a project.json file. This is similar to the node.js packages.json file. This file contains basic project information, the dependencies (NuGet libraries) and the supported frameworks. It also contains one or more commands that can be executed from command line. In this case one command is defined ‘Web’ which starts Kestrel on port 3008. Kestrel is the ASP.NET Core cross platform development web server use to run the web-application.

Click here to view the project.json file specifications. And here for more specific ASP.NET Core project.json configuration

Tooling

One of the great decision they made is to leverage improved command line experience. I like this because this improves productivity and multi-platform support. Instead of running the application from your way-to-heavy Visual Studio you can now run your applications from command line with a single command.

To run dnx a command defined in your project.json you have to call dnx followed by the command you want to run:

.NET Core also supports a command-line .NET Version Manager (dnvm) and a package manager (dnu). Which is great for automating environment setup, builds and deployment.

What is different

Following list describes the main difference between ASP.NET and ASP.NET Core:

• Web Pages and apis are supported by a single model. Instead of using a different controller from serving Web (MVC) and Api (WebApi) requests there is only one base controller left named Controller. This controller used to implement both scenarios. Here you can see and example of an Api controller and here an example of a Web Page controller.
• Dependency Injection is now a first class citizen. This is very basic support but it is easy to plug-in your favorite container. Lucky there are already containers that support the new dnx framework like Autofac and StructureMap.
• All application configuration code is now grouped in a single StartUp.js and the Global.asax is not supported anymore. This class will take care of the container initialization and the web-application configuration. An example of the Startup.cs file can be viewed here.
• Multiple environments are supported out of the box. Application configuration settings can come now from different sources instead of from a single app.config file. This is a powerful way to differ the configuration for each environment.
  
  Configuration with different sources.

  private IConfigurationRoot SetupConfiguration(IHostingEnvironment env) { var builder = new ConfigurationBuilder() .AddJsonFile("appsettings.json") .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true) .AddJsonFile("appsettings.private.json", optional: true) .AddEnvironmentVariables(); return builder.Build(); }

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  private IConfigurationRoot SetupConfiguration(IHostingEnvironment env) {    var builder = new ConfigurationBuilder()       .AddJsonFile("appsettings.json")       .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)       .AddJsonFile("appsettings.private.json", optional: true)       .AddEnvironmentVariables();    return builder.Build(); }

Conclusion

Microsoft had a good look at the competing web-development frameworks when they designed the new ASP.NET Core version. This results in my opinion into a modern web-framework adapted to the need of today’s web projects.

Source code

The source code of the application can be found on github:

https://github.com/tim-cools/RealTimeWeb.NET

Warning!

The application is still work in progress and new features will be added in the next following weeks…

Some of the technologies and frameworks used in this application are pre-release and most likely to change. Currently it is based on RC1 of .NET Core. I try to update the code as soon as possible whenever the final version is released. Ping me on Twitter if you have questions or issues.

RealTimeWeb.NET Blog Posts

This post is part of a blog post series about RealTimeWeb.NET application.

1. RealTimeWeb.NET – A real time ASP.NET Core application
2. Getting started with RealTimeWeb.NET
3. RealTimeWeb.NET Front-end
1. Creating an ASP.NET Core web application
2. Single page application in React on ASP.NET Core
3. React Authentication on ASP.NET Core with OAuth and Identity
4. Real-time data pushed by web-sockets (SignalR) on ASP.NET Core
5. Server-side rendering
4. Real-time back-end
5. Operations
6. ...