In my earlier post, we had seen how we can create a console application using the new .Net core libraries. Moving further, we'll now see how we can use the same .Net core cross-platform libraries to develop and run a basic Hello World web application on Linux(I'll be using Ubuntu 14.04 in this example).

We had already installed Visual Studio Code and .Net core libraries in the earlier post. We need to now install the following...

• Node.js and npm

  • Follow the install instructions here

• Install Yeoman, bower, grunt and gulp using...
  sudo npm install -g yo bower grunt-cli gulp

• Next, install the ASP.Net generator using...
  sudo npm install -g generator-aspnet

With this, we are almost ready to create a new web application.

Let's create a new folder for our web application.

mkdir HelloWorldApp
cd HelloWorldApp

We'll now use Yeoman, to generate the basic structure of the web application.

yo aspnet

Output:

sundeep@sundeep-XPS-L501X:~/Documents/dev/HelloWorldApp$ yo aspnet

     _-----_
    |       |    .--------------------------.
    |--(o)--|    |      Welcome to the      |
   `---------´   |  marvellous ASP.NET Core |
    ( _´U`_ )    |      1.0 generator!      |
    /___A___\    '--------------------------'
     |  ~  |     
   __'.___.'__   
 ´   `  |° ´ Y ` 

? What type of application do you want to create? (Use arrow keys)
❯ Empty Web Application 
  Console Application 
  Web Application 
  Web Application Basic [without Membership and Authorization] 
  Web API Application 
  Nancy ASP.NET Application 
  Class Library 
  Unit test project (xUnit.net)

For the sake of our example here, we'll go ahead with the Empty Web Application option. It will ask us to name this application. Provide some name for the web application and press enter.

Listing contents of this directory will show the following files...

sundeep@sundeep-XPS-L501X:~/Documents/dev/HelloWorldApp/HelloWorldApp$ ls
Dockerfile  Program.cs  project.json  Properties  README.md  Startup.cs  web.config  wwwroot

Just like the earlier post example of console application, the Program.cs file has the main method which serves as the entry point for this web application. Contents of Program.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Hosting;

namespace HelloWorldApp
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var host = new WebHostBuilder()
                .UseKestrel()
                .UseContentRoot(Directory.GetCurrentDirectory())
                .UseIISIntegration()
                .UseStartup<Startup>()
                .Build();

            host.Run();
        }
    }
}

The Startup class, which is part of Startup.cs class is invoked by this main method. This class by default returns Hello World as part of the response. Contents of Startup.cs file.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;

namespace HelloWorldApp
{
    public class Startup
    {
        // This method gets called by the runtime. Use this method to add services to the container.
        // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
        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.Run(async (context) =>
            {
                await context.Response.WriteAsync("Hello World!");
            });
        }
    }
}

The project.json file is the configuration file for the web application, the contents of which are as follows...

{
  "dependencies": {
    "Microsoft.NETCore.App": {
      "version": "1.0.0-rc2-3002702",
      "type": "platform"
    },
    "Microsoft.AspNetCore.Server.IISIntegration": "1.0.0-rc2-final",
    "Microsoft.AspNetCore.Server.Kestrel": "1.0.0-rc2-final"
  },

  "tools": {
    "Microsoft.AspNetCore.Server.IISIntegration.Tools": {
      "version": "1.0.0-preview1-final",
      "imports": "portable-net45+win8+dnxcore50"
    }
  },

  "frameworks": {
    "netcoreapp1.0": {
      "imports": [
        "dotnet5.6",
        "dnxcore50",
        "portable-net45+win8"
      ]
    }
  },

  "buildOptions": {
    "emitEntryPoint": true,
    "preserveCompilationContext": true
  },

  "runtimeOptions": {
    "gcServer": true
  },

  "publishOptions": {
    "include": [
      "wwwroot",
      "web.config"
    ]
  },

  "scripts": {
    "postpublish": [ "dotnet publish-iis --publish-folder %publish:OutputPath% --framework %publish:FullTargetFramework%" ]
  },

  "tooling": {
    "defaultNamespace": "HelloWorldApp"
  }
}

Just like the console application covered in the earlier post, this file has all details related to the .Net core libraries version being used, the Nuget package dependencies, the tooling used etc. We need to use the dotnet command line tools to restore these packages.

dotnet restore

Output:

sundeep@sundeep-XPS-L501X:~/Documents/dev/HelloWorldApp/HelloWorldApp$ dotnet restore
log  : Restoring packages for /home/sundeep/Documents/dev/HelloWorldApp/HelloWorldApp/project.json...
info :   CACHE https://api.nuget.org/v3-flatcontainer/microsoft.netcore.dotnethostresolver/index.json
info :   CACHE https://api.nuget.org/v3-flatcontainer/microsoft.netcore.dotnethost/index.json
log  : Restoring packages for tool 'Microsoft.AspNetCore.Server.IISIntegration.Tools' in /home/sundeep/Documents/dev/HelloWorldApp/HelloWorldApp/project.json...
info : Committing restore...
log  : Lock file has not changed. Skipping lock file write. Path: /home/sundeep/Documents/dev/HelloWorldApp/HelloWorldApp/project.lock.json
log  : /home/sundeep/Documents/dev/HelloWorldApp/HelloWorldApp/project.json
log  : Restore completed in 1587ms.

NuGet Config files used:
    /home/sundeep/.nuget/NuGet/NuGet.Config

Feeds used:
    https://api.nuget.org/v3/index.json
sundeep@sundeep-XPS-L501X:~/Documents/dev/HelloWorldApp/HelloWorldApp$

Next, we can build the web application using

dotnet build

Output:

sundeep@sundeep-XPS-L501X:~/Documents/dev/HelloWorldApp/HelloWorldApp$ dotnet build
Project HelloWorldApp (.NETCoreApp,Version=v1.0) will be compiled because expected outputs are missing
Compiling HelloWorldApp for .NETCoreApp,Version=v1.0

Compilation succeeded.
    0 Warning(s)
    0 Error(s)

Time elapsed 00:00:06.0706350

If this is successful, we can now run the asp.net application using

dotnet run

Output:

sundeep@sundeep-XPS-L501X:~/Documents/dev/HelloWorldApp/HelloWorldApp$ dotnet run
Project HelloWorldApp (.NETCoreApp,Version=v1.0) was previously compiled. Skipping compilation.
Hosting environment: Production
Content root path: /home/sundeep/Documents/dev/HelloWorldApp/HelloWorldApp
Now listening on: http://localhost:5000
Application started. Press Ctrl+C to shut down.

This uses the cross-platform kestrel web server to host the application. You can now open a browser of your choice and enter the url http://localhost:5000 This will bring up Hello World on the browser output screen.

While there are a lot of concepts and details behind the steps that we have done above, this was supposed to be a quick start to just get you up and running the asp.net web application on Linux.

You may check out the official documentation of ASP.Net core here

Hope this was useful!