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Asked: 2026-05-13T23:02:43+00:00

I am trying to use a COMET solution using ASP.NET . Trouble is I

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I am trying to use a COMET solution using ASP.NET .

Trouble is I want to implement sending and notification part in the same page.
On IE7, whenever I try to send a request, it just gets queued up.
After reading on internet and stackoverflow pages I found that I can only do 2 simultaneous asyn ajax requests per page.

So until I close my comet Ajax request, my 2nd request doesn’t get completed, doesn’t even go out from the browser. And when I checked with Firefox I just one Ajax comet request running all time..so doesn’t that leave me one more ajax request?

Also the solution uses IRequiressessionstate for Asynchronous HTTP Handler which I had removed. But it still creates problems on multiple instances of IE7.

I had one work around which is stated here http://support.microsoft.com/kb/282402
it means we can increase the request limit from registry by default is 2.
By changing “MaxConnectionsPer1_0Server” key
in hive “HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings”
we can increase the number of requests.

Basically I want to broadcast information to multiple clients connected to a server using Comet and the clients can also send messages to the Server.
Broadcasting works but the send request back to server doesn’t work.

I’m using IIS 6 and ASP.NET .

Are there any more workarounds or ways to send more requests?

References :

How many concurrent AJAX (XmlHttpRequest) requests are allowed in popular browsers?

AJAX, PHP Sessions and simultaneous requests

jquery .ajax request blocked by long running .ajax request

jQuery: Making simultaneous ajax requests, is it possible?

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1 Answer

  1. Editorial Team

    You are limited to 2 connections, but typically that’s all you need – 1 to send, 1 to receive, even in IE.

    That said, you can totally do this; we do it all the time in WebSync. The solution lies in subdomains.

    The thing to note is that IE (and other browsers, although they typically limit to 6 requests, not 2) limits requests per domain – but that limitation is for the entire domain excluding subdomains. So for example, you can have 2 requests open to “www.stackoverflow.com” and 2 more requests open to “static.stackoverflow.com”, all at the same time.

    Now, you’ve got to be somewhat careful with this approach, because if you make a request from the www subdomain to the static subdomain, that’s considered a cross-domain request, so you’re immediately limited to not using direct XHR calls, but at that point you have nevertheless bypassed the 2 connection limit; JSONP, HTML5, etc, are all your friend for bypassing the cross-domain limitations.

    Edit

    Managing with > 1 instance of IE comes back to the same problem. The limitation applies across all instances. So, if you have two browsers open, and they’re both using comet, you’re stuck with 2 long-polling connections open. If you’ve maximized your options, you’re going to be connecting those long-polling requests to something like “comet.mysite.com”, and your non-long-polling requests will go to “mysite.com”. That’s the best you’ll get without going into wildcard DNS.

    Check out some of our WebSync Demos; they work in 2 instances of IE without a problem. If you check out the source, you’ll see that the DNS for the streaming connection is different from the main page; we use JSONP to bypass the cross-domain limitation.

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