using System;

using System.Threading;

public class Program

{

    public static void Main()

    {

        var videoEncoder = new VideoEncoder();

        var email = new EmailService();

        var message = new MessageService();

        videoEncoder.VideoEncoded += email.OnVideoEncoded;

        videoEncoder.VideoEncoded += message.OnVideoEncoded;

        videoEncoder.Encode("Test Video");

    }

}

​

class EmailService

{

    public void OnVideoEncoded(object sender, EventArgs e)

    {

        Console.WriteLine("Sent an email");

    }

}

​

class MessageService

{

    public void OnVideoEncoded(object sender, EventArgs e)

    {

        Console.WriteLine("Sent a message");

    }

}

​

​

class VideoEncoder

{

    public delegate void VideoEncodedEventHandler(object sender, EventArgs e);

    public event VideoEncodedEventHandler VideoEncoded;

    public void Encode(string video)

    {

        Console.WriteLine(string.Format("{0} Video encoding", video));

        Thread.Sleep(3000);

        Console.WriteLine("Video encoding completed");

        OnVideoEncoded();

    }

    public virtual void OnVideoEncoded()

    {

        if(VideoEncoded != null)

        {

            VideoEncoded(this, EventArgs.Empty);

        }

    }

}