Asynchronous Webrequest best practices

Question

What is the best practice for getting a webrequest asynchronously?

I want to download a page from the internet (doesn't matter what) and avoid blocking a thread as much as possible.

Previously I believed that it was enough to just use the 'BeginGetResponse' and 'EndGetResponse' pair. But on closer inspection I also see that there is the option of using 'BeginGetRequestStream'

[UPDATE] GetRequestStream is used for POST operations

And then to add to the confusion, Should I be using stream.BeginRead and EndRead?

[UPDATE] this article suggests it is even better to process the HttpResponse.GetResponseStream asynchronously using Stream.BeginRead

What a mess!

Can someone point me in the right direction?

What is the Best Practice?

Answer 1

The following article appears to have a good tutorial on using HttpWebRequest asynchronously using threads:

http://www.developerfusion.com/code/4654/asynchronous-httpwebrequest/

Answer 2

1. You use Begin/EndGetResponse to asynchonously wait for the HTTP response. If you are doing a POST and need to send a lot of data asynchronously, use Begin/EndGetRequestStream.

2. This isn't unique to asynchronous communication - you can look up the synchronous versions to get additional info.

3. I'm not sure why you would be doing a Read on the request stream - most likely you'll be writing to it, and reading from the Response stream.

Finally, Jeffrey Richter's blog has an article about some of the subtleties of HttpWebRequest and streams.

Answer 3

Have you considered doing the web request in a new thread?

http://msdn.microsoft.com/en-us/library/ms173178.aspx

Answer 4

You could code this all yourself or you could just use WebClient which does a lot of the grunt work for you. For example, to download file as a string you would call DownloadStringAsync() which eventually will trigger the OnDowloadStringCompleted event. If the file is binary you might try using DownloadDataAsync() instead.