How can I send a notification message from server to all clients in WCF (broadcast you can say)? - wcf

Question

I want to send notification message every second from net tcp WCF service to all clients,
Broadcast you can say?
After the helpful answers
I wrote the following method that will send notifications (heartbeat) to all connected users
foreach (IHeartBeatCallback callback in subscribers)
{
ThreadPool.QueueUserWorkItem(delegate(object state)
{
ICommunicationObject communicationCallback = (ICommunicationObject)callback;
if (communicationCallback.State == CommunicationState.Opened)
{
try
{
callback.OnSendHeartBeat(_heartbeatInfo.message, _heartbeatInfo.marketstart,_heartbeatInfo.marketend, _heartbeatInfo.isrunning, DateTime.Now);
}
catch (CommunicationObjectAbortedException)
{
Logger.Log(LogType.Info, "BroadCast", "User aborted");
communicationCallback.Abort();
}
catch (TimeoutException)
{
Logger.Log(LogType.Info, "BroadCast", "User timeout");
communicationCallback.Abort();
}
catch (Exception ex)
{
Logger.Log(LogType.Error, "BroadCast", "Exception " + ex.Message + "\n" + ex.StackTrace);
communicationCallback.Abort();
}
}
else
{
DeletionList.Add(callback);
}
}
);
}
I am worried about calling the callback method as the client may close his application, but I handled it using the try catch, decrease the timeout, and send the broad cast in parallel, so is that sufficient?

Answer 1

You'll need to setup a callback service; I wrote a simple beginners guide a while back

Answer 2

In order to do that, you need to create and mantain a list of all connected clients (the general practice to fo this is creating LogIn and LogOut methods to create and manage a list of object representing your clients incuding their CallbackContext).
Then, with a System.Time.Timers, you can loop through the connected client list and send the notification.
Tip. this method could also act as a Keep-Alive or Hear-Beat method (if this isn't it's purpose by design) by adding the possiblity to remove clients from your list if the service cannot send the callback to them.