How to write an asynchronous method? - windows-phone-7

Question

I have a method that performs Http POST, and since I'm using HttpWebRequest to perform it, the method relies on asynchronous calls. Since I need my method to return the response code of my Http POST, I want to make my method asynchronous. How do I do this?
I was thinking of using Dispatcher.
EDIT: So a basic outline of the structure of my code looks like this:
string response;
string httpPost(){
HttpWebRequest.BeginGetRequestStream(new AsyncCallback(requestCallback), httpWebRequest);
return response;
}
void requestCallback(IAsyncResult asyncResult){
HttpWebRequest.EndGetRequestStream(asyncResult);
HttpWebRequest.BeginGetResponse(new AsyncCallback(responseCallback), httpWebRequest);
}
void responseCallback(IAsyncResult asyncResult){
HttpWebResponse webResponse = (HttpWebResponse) HttpWebRequest.EndGetResponse(asyncResult);
response = webResponse.StatusCode.ToString();
}
I want to change httpPost() to an asynchronous method.
EDIT2:
public static void httpPost(Action<string> completed)
{
HttpWebRequest.BeginGetRequestStream(new AsyncCallback(requestCallback), httpWebRequest);
completed(HttpEngine.response);
}

Answer 1

On WP7, HTTPWebRequest will already be asynchronous - for an example of its use, see this code from http://www.rudigrobler.net/blog/wp7-webclient-vs-httpwebrequest
public void DoThePost(Action<string> onSuccess)
{
var request = (HttpWebRequest)WebRequest.Create(new Uri("http://www.sherdog.com/rss/news.xml"));
request.BeginGetResponse(r =>
{
var httpRequest = (HttpWebRequest)r.AsyncState;
var httpResponse = (HttpWebResponse)httpRequest.EndGetResponse(r);
using (var reader = new StreamReader(httpResponse.GetResponseStream()))
{
var response = reader.ReadToEnd();
Deployment.Current.Dispatcher.BeginInvoke(new Action(() =>
{
onSuccess(response);
}));
}
}, request);
}
Called with:
DoPost((responseText) => { responseTextBlock.Text = responseText;});