C# Event & delegate

using System;
 
namespace ConsoleApp3
{
    class Program
    {
        static void Main(string[] args)
        {
            var video = new Video() { Title = "Video 1" };
            var videoEncoder = new VideoEncoder();  //Publisher
            var mailService = new MailService();    //Subscriber
            var messageService = new MessageService();  
 
            videoEncoder.VideoEncoded += mailService.OnVideoEncoded;
            videoEncoder.VideoEncoded += messageService.OnVideoEncoded;
 
            videoEncoder.Encode(video);
 
            Console.ReadLine();
        }
    }
}
 

using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;
 
namespace ConsoleApp3
{
    public class VideoEventArgs : EventArgs
    {
        public Video Video { get; set; }
    }
 
    public class VideoEncoder
    {
        // 1. 델리게이트 정의 
        // 2. 델리게이트기반의 이벤트 정의 
        // 3. 이벤트 실행 
        public delegate void VideoEncodedEventHandler(object source, VideoEventArgs arg);
 
        //public event VideoEncodedEventHandler VideoEncoded;
        public event EventHandler<VideoEventArgs> VideoEncoded;
        //public event EventHandler VideoEncoded;
 
        public void Encode(Video video) {
            Console.WriteLine("Encoding Video...");
            Thread.Sleep(3000);
 
            OnVideoEncoded(video);
        }
 
        protected virtual void OnVideoEncoded(Video video)
        {
            if (VideoEncoded != null)
            {
                VideoEncoded(this, new VideoEventArgs() {Video = video});
            }
        }
    }
}
 

using System;
using System.Collections.Generic;
using System.Text;
 
namespace ConsoleApp3
{
    public class Video
    {
        public string Title { get; set; }
    }
}
 

using System;
 
namespace ConsoleApp3
{
    public class MailService
    {
        public void OnVideoEncoded(object source, VideoEventArgs args) {
            Console.WriteLine("MailingService: Sending an email..." + args.Video.Title);
        }
    }
}

using System;
 
namespace ConsoleApp3
{
    public class MessageService
    {
        public void OnVideoEncoded(object source, VideoEventArgs args)
        {
            Console.WriteLine("MessageService: Sending a text message..." + args.Video.Title);
        }
    }
}