Question

I want to send a message from a server to all clients. There are 0-* clients. The server may or may not be running when a client is loaded. The functionality here works how I want it. I am trying to figure out if this can be done without Thread.Sleep()? Also note that the clients and the server are each in independant processes.

Server Portion

class NamedEventsServer
{
    internal static void Main()
    {
        const string ewhName = "StickyNoteEwh";

        EventWaitHandle ewh = null;
        bool doesNotExist = false;
        bool wasCreated;

        // Attempt to open the named event.
        try
        {
            ewh = EventWaitHandle.OpenExisting(ewhName);
        }
        catch (WaitHandleCannotBeOpenedException)
        {
            Console.WriteLine("Named event does not exist.");
            doesNotExist = true;
        }
        if (doesNotExist)
        {
            // The event does not exist, so create it.

            ewh = new EventWaitHandle(true,
                EventResetMode.ManualReset,
                ewhName,
                out wasCreated);

            if (wasCreated)
            {
                Console.WriteLine("Created the named event.");
            }
            else
            {
                Console.WriteLine("Unable to create the event.");
                return;
            }
        }
        ewh.Set();
        Thread.Sleep(1000);//wait one second...giving threads enough time to all respond.  Then stop triggering the event.
        ewh.Reset();

        //exit
    }
}

Client Portion

class NamedEventsClient
{
    internal static void Main()
    {
        const string ewhName = "StickyNoteEwh";

        while (true)
        {
            EventWaitHandle ewh = null;
            bool doesNotExist = false;
            bool wasCreated;
            // Attempt to open the named event.
            try
            {
                ewh = EventWaitHandle.OpenExisting(ewhName);
            }
            catch (WaitHandleCannotBeOpenedException)
            {
                Console.WriteLine("Named event does not exist.");
                doesNotExist = true;
            }
            if (doesNotExist)
            {
                // The event does not exist, so create it.

                ewh = new EventWaitHandle(false,
                    EventResetMode.ManualReset,
                    ewhName,
                    out wasCreated);

                if (wasCreated)
                {
                    Console.WriteLine("Created the named event.");
                }
                else
                {
                    Console.WriteLine("Unable to create the event.");
                    return;
                }
            }
            Console.WriteLine("Wait on the event.");
            ewh.WaitOne();
            Console.WriteLine("Event was signaled.");
            //Console.WriteLine("Press the Enter key exit.");
            Thread.Sleep(1000);
            //Console.ReadLine();
        }
    }
}

Answer 1

I guess it depends whether you’re certain all clients are going to get their time-slice within on second. It sounds reasonable, but under extreme stress some clients might miss it. How crucial is that?

Anyway, I think this is exactly the kind of thing you should use ZeroMQ for. It’s light-weight, and takes care of all the potential bugs for you.