C# How to create a Singleton that publishes events & Classes that subscribe?

Question

Goal: Have a singleton publish events and allow any class to subscribe/listen to those events

Problem: I cannot figure out how to do this. The code below is illegal but it purveys what I'm trying to do

TransmitManager Class - Publisher

    //Singleton
    public sealed class TransmitManager
    {

        delegate void TransmitManagerEventHandler(object sender);
        public static event TransmitManagerEventHandler OnTrafficSendingActive;
        public static event TransmitManagerEventHandler OnTrafficSendingInactive;

        private static TransmitManager instance = new TransmitManager();



        //Singleton
        private TransmitManager()
        {

        }

        public static TransmitManager getInstance()
        {
            return instance;
        }

        public void Send()
        {
           //Invoke Event
           if (OnTrafficSendingActive != null)
              OnTrafficSendingActive(this);

          //Code connects & sends data

          //Invoke idle event
          if (OnTrafficSendingInactive != null)
            OnTrafficSendingInactive(this);

       }
   }

Test Class - Event Subscriber

   public class Test
   {

     TrasnmitManager tm = TransmitManager.getInstance();

     public Test()
     {
        //I can't do this below. What should my access level be to able to do this??

        tm.OnTrafficSendingActive += new TransmitManagerEventHandler(sendActiveMethod);

     }

     public void sendActiveMethod(object sender)
     {

        //do stuff to notify Test class a "send" event happend
     }
  }

Answer 1

You shouldn't need to make the events static .

public event TransmitManagerEventHandler OnTrafficSendingActive;
public event TransmitManagerEventHandler OnTrafficSendingInactive;

Answer 2

Either your events have to be instance members or you have to address them as static.

TransmitManager.OnTrafficSendingActive +=...

OR

public event TransmitManagerEventHandler OnTrafficSendingActive;

...

TransmitManager.Instance.OnTrafficSendingActive+=...

Also: use EventHandler as your event delegate. Consider making a custom arguments class and pass the status to just one event instead of multiple events. This will let you pass status messages as well.