using System;

public class Program

{

    public static void Main()

    {

        ProcessBusinessLogic bl = new ProcessBusinessLogic();

        bl.ProcessCompleted += bl_ProcessCompleted; // register with an event

        bl.StartProcess();

    }

​

    // event handler

    public static void bl_ProcessCompleted(object sender, ProcessEventArgs e)

    {

        Console.WriteLine("Process " + (e.IsSuccessful? "Completed Successfully": "failed"));

        Console.WriteLine("Completion Time: " + e.CompletionTime.ToLongDateString());

    }

}

​

public class ProcessEventArgs : EventArgs

{

    public bool IsSuccessful { get; set; }

    public DateTime CompletionTime { get; set; }

​

}

​

public class ProcessBusinessLogic

{

    public event EventHandler<ProcessEventArgs> ProcessCompleted; // event

​

    public void StartProcess()

    {

        var data = new ProcessEventArgs();

        try

        {

            Console.WriteLine("Process Started!");

            //uncomment following to see the result

            //throw new NullReferenceException();

            // some process code here..

            data.IsSuccessful = true;

            data.CompletionTime = DateTime.Now;

            OnProcessCompleted(data);

        }

        catch(Exception ex)

        {

            data.IsSuccessful = false;

            data.CompletionTime = DateTime.Now;

            OnProcessCompleted(data);

        }

    }

​

​

    protected virtual void OnProcessCompleted(ProcessEventArgs e)

    {

        ProcessCompleted?.Invoke(this, e);

    }

}