Is it possible to create asp.net web application like APE( Ajax Push Engine )?

Question

APE, It's the best idea for 2 ways connections between client & server. I think I can create ajax push engine based on Asp.net like the following code.

Server-side ( WCF or .Net Web Service )

public string SendRequest()
{
    string data = Request["data"];

    if(String.IsNullOrEmpty(data))
    {
        // still connect to client until server has new data for send to client.
        while(!HasNewData())
        {
            Thread.Sleep(100);
        }

        // send new data to client.
        JSONResponse.Send(GetNewData());
    }
    else
    {
        // Save data via Extension Method for easy to understand.
        data.Save();

        // Send response using default json template.
        return JSONResponse.Complete;
    }
}

But I have some problem about performance when server connect more than 100 client at the same time. Which is the best performance in server term?

• Client request server every few second.
• Client request server after server response last request.

Source : Ajax Push Engine - Real time data streaming

Thanks,