long Polling webservice

Question

I have a webpage what asks through jQuery json data from webservice after every 1 second. If there is no data then webservice returns null.

The problem is that if client is on site over 24 hours then the browser will collect too much data and will crash. So I decided to set timeout to 60000 in jQuery ajax so it will wait for data and on server side I am trying to to somthing like this:

while(true)
{
  if(thereIsData){
     System.Web.Script.Serialization.JavaScriptSerializer oSerializer =
     new System.Web.Script.Serialization.JavaScriptSerializer();
     string sJSON = oSerializer.Serialize(ActionList);
     Context.Response.Output.Write(sJSON);
     return;
  }
 Thread.Sleep(1000);
}

But if I use Thread.Sleep then it will lock entire page. I have tried threading EventWaitHandle and same result entire page is locked until there is data. I also tried creating other webservice but same results. Is there any way that I can do this?

Answer 1

Why don't you just count up the number of times it has requested the data, and when it has requested more than 1000 items, for example, then return null after that point.

Or get the code making the webservice call to do something similar and only call it a maximum number of times before it stops trying.

Answer 2

It sounds similar to a "chat" like application. One of the algorithms for handling this would be to have a progressively "sliding scale" of polling such as:

1) If no updates have come back in n-minutes, bump polling rate up to three seconds 2) If no updates for another n-minutes, bump poll rate up to 5 seconds, then 10 etc 3) When you "have activity (non null return value), slide it back down to 1 second polls and repeat steps 1 and 2.....