Asynchronous Method Calls using Delegate

Asynchronous method call means main execution goes continue and method executed parallel, when method execution gets completed it notifies back to main execution program / caller (client).

Example

namespace AsyncCallBack

{

    class Program

    {

        public delegate string delTask();

        public static string results;

        static void Main(string[] args)

        {

            clsBigTask objclsTask = new clsBigTask();

            delTask del = objclsTask.BigTask;

          

            AsyncCallback asyncCall = new AsyncCallback(CallBackMethod);

            del.BeginInvoke(asyncCall, del);

          

            Console.WriteLine("Main task completed @" + DateTime.Now.ToString());

            Console.ReadLine();

        }

        public static void CallBackMethod(IAsyncResult result)

        {

            delTask mydel = (delTask)result.AsyncState;

            results = mydel.EndInvoke(result);

            Console.WriteLine(results);

        }

    }

    public class clsBigTask

    {

        public string BigTask()

        {

            Thread.Sleep(6000);

            return "Big Task completed";

        }

    }

}

Output