在ASP.NET上使用服务器发送的事件时如何检测断开连接？

Question

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.

Answer 1

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.