c# - How to detect a disconnection when using Server-sent events on ASP.NET? - Stack Overflow

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I have the following SSE handler in ASP.NET

Response.ContentType = "text/event-stream";
while (true)
{
    Response.Write(string.Format("data: {0}\n\n", DateTime.Now.ToString()));
    Response.Flush();
    System.Threading.Thread.Sleep(1000);
}

It runs indefinitely, even after I closed the client application. How to notify the server to stop the handler?

I tried on the client:

var source = new EventSource('Handler.aspx');
window.onunload = function() {
     source.close();
}

But I didn't succeed.

I have the following SSE handler in ASP.NET

Response.ContentType = "text/event-stream";
while (true)
{
    Response.Write(string.Format("data: {0}\n\n", DateTime.Now.ToString()));
    Response.Flush();
    System.Threading.Thread.Sleep(1000);
}

It runs indefinitely, even after I closed the client application. How to notify the server to stop the handler?

I tried on the client:

var source = new EventSource('Handler.aspx');
window.onunload = function() {
     source.close();
}

But I didn't succeed.

• c#
• javascript
• asp
• html
• server-sent-events

Share Improve this question Follow edited Mar 16, 2012 at 19:19 Dagg Nabbit 76.8k1919 gold badges114114 silver badges142142 bronze badges asked Mar 16, 2012 at 19:17 Jader DiasJader Dias 90.7k160160 gold badges435435 silver badges633633 bronze badges 11

• If this is just to show a live clock, you may want to look into a JavaScript equivalent that does the same thing. – AaronS Commented Mar 16, 2012 at 19:22
• 3 @AaronS I'm pretty sure using DateTime.Now is just OPs example. – Bala R Commented Mar 16, 2012 at 19:23
• @Bala R You're probably right, but doesn't hurt to check. – AaronS Commented Mar 16, 2012 at 19:24
• You'll need to make your while breakable and have the client send a message when it wants the server to break. – M.Babcock Commented Mar 16, 2012 at 19:26
• 1 I feel like the best way to do something like this would be a push style request ing from the client, which the server sits on until it's time to respond, responds to, and a new request is immediately opened. Then you never have hanging requests (longer than the timeout, anyway) – Chris Carew Commented Mar 16, 2012 at 19:53

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1 Answer 1

Sorted by: Reset to default 4

You could use the IsClientConnected property of the HttpResponse class to detect client diconnection.

Here is a small example:

Response.ContentType = "text/event-stream";
while (true)
{
  Response.Write(string.Format("data: {0}\n\n", DateTime.Now.ToString()));
  Response.Flush();

  if (Response.IsClientConnected == false)
  {
    break;
  }
  System.Threading.Thread.Sleep(1000);
}

So, using the IsClientConnected property you should be able to detect:

1. On the client side closing the source by using source.close().
2. Closing the connection by closing the browser window or navigating to another website.

I've tested my code using ASP.Net 4.0 and Google Chrome.

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