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; 
using Microsoft.Extensions.Logging; 
namespace FirstAppDemo { 
 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 http://go.microsoft.com/fwlink/"Hello World!"); 
  }); 
 } 
 } 
}

{ 
 "message": "Hello, World! this message is from configuration file..." 
}

using Microsoft.AspNet.Builder; 
using Microsoft.AspNet.Hosting; 
using Microsoft.AspNet.Http; 
using Microsoft.Extensions.DependencyInjection; 
using Microsoft.Extensions.Configuration; 
namespace FirstAppDemo { 
 public class Startup { 
 public Startup() { 
  var builder = new ConfigurationBuilder() 
  .AddJsonFile("AppSettings.json"); 
  Configuration = builder.Build(); 
 } 
 public IConfiguration Configuration { get; set; } 
 
 // 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 http://go.microsoft.com/fwlink/"message"]; 
  await context.Response.WriteAsync(msg); 
  }); 
 } 
  
 // Entry point for the application. 
 public static void Main(string[] args) =7gt; WebApplication.Run<Startup>(args); 
 } 
}