EventBasedAsynchronousPattern_EAP created by kenanhancer - https://repl.it/@kenanhancer/EventBasedAsynchronousPatternEAP

EventBasedAsynchronousPattern_EAP.cs

using System;
using System.Net;
using System.Threading.Tasks;

class MainClass {
  public static void Main (string[] args) {
    CustomDnsWithEAP.GetHostEntryCompleted += CustomDnsWithEAP_GetHostEntryCompleted;

    CustomDnsWithEAP.GetHostEntryAsync("www.kenanhancer.com");

    CustomDnsWithEAP.GetHostEntryAsync("github.com");

    Console.ReadLine();
  }

  private static void CustomDnsWithEAP_GetHostEntryCompleted(object sender, CustomDnsEventArgs<IPHostEntry> e)
  {
    Console.WriteLine(e.Result.HostName);
  }
}

public class CustomDnsEventArgs<TResult> : EventArgs
{
    public TResult Result
    {
        get;
        private set;
    }

    public CustomDnsEventArgs(TResult result)
    {
        Result = result;
    }
}

public static class CustomDnsWithEAP
{
    public static event EventHandler<CustomDnsEventArgs<IPHostEntry>> GetHostEntryCompleted;

    private static void RaiseGetHostEntryCompleted(IPHostEntry result)
    {
        var handler = GetHostEntryCompleted;
        if (handler != null)
        {
            handler(null, new CustomDnsEventArgs<IPHostEntry>(result));
        }
    }

    public static void GetHostEntryAsync(string hostNameOrAddress)
    {
        Task.Run(() =>
        {
            IPHostEntry host = Dns.GetHostEntry(hostNameOrAddress);

            RaiseGetHostEntryCompleted(host);
        });
    }
}