Return response from HTTPWebRequest somehow? - windows-phone-7

Question

I'm trying to validate a user in my WP7 app by validating username/pass on a server.
In my "validate user" method I create a HTTPWebRequest with the stuff I need validated.
Then as far as I can see, the only option to execute is to use request.BeginGetResponse, with an async callback.
But I want to return the response from the request in the same method that I created the request in, how can I accomplish this?

Answer 1

I'm not sure why you would like to make it return in the calling method. I would just use the standard WebClient behavior like below:
public void ValidateUser()
{
WebClient webClient = new WebClient();
Uri uri = new Uri(url);
webClient.DownloadStringCompleted += new DownloadStringCompletedEventHandler(webClient_DownloadStringCompleted);
webClient.DownloadStringAsync(new Uri(url));
}
void webClient_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
//Validate result from response by using e.Result
}

Answer 2

BeginGetResponse returns an IAsyncResult which has a wait handle that is signalled when the request completes. All you have to do is wait on this handle: [ doesn't work on WP7 ]
UPDATE: use a ManualResetEvent
var mre = new ManualResetEvent( false );
var iar = myHttpWebRequest.BeginGetResponse( state => mre.Set(), null );
mre.WaitOne();
var response = myHttpWebRequest.EndGetResponse( iar );

Answer 3

The only real way to achieve what you need would be to create an event in your worker class, and fire that event when the async call completes, so (pseudocode)...
void StartDownload(object[] parameters)
{
var req = HttpWebRequest.Create("http://google.com");
req.BeginGetRequestStream(Completed_handler, req);
}
void Completed_handler(object sender, DownloadStringCompletedEventArgs e)
{
var request = (HttpWebRequest)result.AsyncState;
var response = request.EndGetResponse(result);
using (var stream = response.GetResponseStream())
using (var reader = new StreamReader(stream))
{
var contents = reader.ReadToEnd();
NotifyCallerOfContent(contents)
}
}
public event EventHandler<MyCustomEventArgsClass> DownloadHasFinished;
public NotifyCallerOfDownload(string content)
{
if(null != DownloadHasFinished)
{
DownloadHasFinished(this, new MyCustomEventArgsClass(content));
}
}
and then subscribe to the DownloadHasFinished event in your calling class.
As for calling out specifically by a HttpWebRequest, take a look at this question, where you will find some working samples.