It's time to get our hands dirty. Let us create a simple ASP.NET 5 application. Fire up Visual Studio and follow these steps:
- Create a project by selecting File | New Project in Visual Studio. The first option is for creating an earlier version of the ASP.NET Web application. The second option is for creating the ASP.NET Core application using the .NET Core framework. The third option is for creating the ASP.NET Core application using the .NET framework. The difference between the second and third option is that the .NET framework supports all the functionalities of existing .NET frameworks whereas .NET Core supports only the core functionalities. The advantage of using the .NET core library is that it can be deployed on any platform.
- Select the Empty template from the list of ASP.NET 5 templates. The second option is for creating the Web API application (for building the HTTP-based services) and the third option is for creating a web application containing some basic functionalities which you can run just from out of the box without you ever needing to write anything.
- Once you click OK in the window as shown in the preceding screenshot, (after selecting the Empty template option) a solution will be created as shown in the following screenshot:
- When you run the application (by pressing F5) without any changes, you'll get the simple Hello World! text on your screen as shown in the following screenshot:
We have not done any coding in this newly created application. So, have you thought about how it displays the text Hello World!?
The answer lies in the Startup.cs file, which contains a class by the name of Startup. This class contains the Main method, which acts as the entry point for the web application. If you have used any of the previous versions of ASP.NET MVC, or even ASP.NET Web Forms, this would not be the case.
ASP.NET 5 runtime calls the ConfigureServices and Configure methods. For example, if you want to configure any service, you can add it here. Any custom configuration for your application can be added to this Configure method:
public void ConfigureServices(IServiceCollection services) {
}
// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app) {
app.UseIISPlatformHandler();
app.Run(async (context) => {
await context.Response.WriteAsync("Hello World!");
});
}
There are only a couple of statements in the Configure method. The first statement tells the run-time to use the IISPlatformHandler for handling all the incoming HTTP requests. Let us leave aside async, await, and context for the moment in the second statement, which we will discuss later. In essence, the second statement tells the run-time to return Hello World! for all the incoming requests irrespective of the incoming URL.
When you type the URL http://localhost:50140/Hello in your browser, it will still return the same Hello World!.
This is the reason we got the Hello World! when we ran the application.
As we have chosen the Empty template while creating the ASP.NET 5 application, no component will have been installed. Even MVC wouldn't be installed by default when you select the Empty template as we did.
You can confirm it by opening the project.json file, where you can see no ASP.NET MVC is mentioned in the list of dependencies:
"dependencies": {
"Microsoft.AspNet.IISPlatformHandler": "1.0.0-rc1-final",
"Microsoft.AspNet.Server.Kestrel": "1.0.0-rc1-final"
},
So first, let us install the ASP.Net Core package for our application.