Event Aggregator DP example

eventAggregation.cs

    interface IMessageSource
    {
        event MessageHandler MessagePublished;
    }

    public delegate void MessageHandler(string message);

    class MessageAggregator
    {
        public event MessageHandler MessagePublished;

        public void Add(IMessageSource messageSource)
        {
            messageSource.MessagePublished += Publish;
        }

        public void Remove(IMessageSource messageSource)
        {
            messageSource.MessagePublished -= Publish;
        }

        private void Publish(string message)
        {
            try
            {
                MessagePublished?.Invoke(message);
            }
            catch (Exception) { }
        }
    }

    class Source : IMessageSource
    {
        private string _message;

        public event MessageHandler MessagePublished;

        public Source(string message)
        {
            _message = message;
        }

        public async Task Ponder()
        {
            var rnd = new Random();
            await Task.Run(async () =>
            {
                for (int i = 0; i < 10; i++)
                {
                    await Task.Delay(TimeSpan.FromMilliseconds(rnd.Next(2000)));
                    MessagePublished?.Invoke(i + ":" + _message);
                }
            });
        }

    }
    class MessageConsumer
    {
        static void Main(string[] args)
        {
            var aggregator = new MessageAggregator();
            aggregator.MessagePublished += Handle;

            var arnold = new Source("Hasta la vista baby");
            aggregator.Add(arnold);

            var robin = new Source("Holy cobwebs, Batman");
            aggregator.Add(robin);

            var djt = new Source("I want a wall and I want it now");
            aggregator.Add(djt);

            Task.WhenAll(arnold.Ponder(), robin.Ponder(), djt.Ponder())
                .GetAwaiter()
                .GetResult();

        }

        private static void Handle(string message)
        {
            Console.WriteLine("Message received: " + message);
        }
    }