Async HttpWebRequest with no wait from within a web application

In my web application (ASP.NET) I have a block of code that uses HttpWebRequest to make a call to a REST service and continue execution. Right now it’s taking longer than I would like to complete the full web request. The thing is that what the REST service returns isn’t useful. Ideally I would like to send an Async web request to the REST service and then NOT wait for a response. The problem is that I’ve tried it out using

Using an IHttpAsyncHandler to call a WebService Asynchronously

Here’s the basic setup. We have an ASP.Net WebForms application with a page that has a Flash application that needs to access an external Web Service. Due to (security I presume) limitations in Flash (don’t ask me, I’m not a Flash expert at all), we can’t connect to the Web Service directly from Flash. The work around is to create a proxy in ASP.Net that the Flash application will call, which will in turn call the WebService and forward the results back to the Flash application.