// C#
BitmapImage bitmapImage = new BitmapImage();
bitmapImage.DownloadProgress += new EventHandler<downloadprogresseventargs>(bitmapImage_DownloadProgress);
bitmapImage.UriSource = new Uri(URL, UriKind.Absolute);
Image newImage = new Image() { Source = _bitmapImage };  

void bitmapImage_DownloadProgress(object sender, DownloadProgressEventArgs e)
{
    int progress = e.Progress; // 0 = 100  

    if (e.Progress == 100)
    {
        // finish
    }
}

The Drupal module provides the following features:

1. Check if user is signed in
2. Create User
3. Sign out user
4. Check the login Credentials In Silverlight

The code demonstrated the following:

1. Limited the selection of JPG and PNG files only
2. Only 1 file can be selected
3. Upload the file with the corresponding file name
4. How to get the file data inside PHP

OpenFileDialog dialog = new OpenFileDialog();
dialog.Filter = "Image Files (.jpg,.png)|*.JPG;*.jpg;*.PNG;*.png";
dialog.FilterIndex = 1;
bool? userClickedOK = _imageDialog.ShowDialog();

// Process input if the user clicked OK.
if (userClickedOK == true)
{
    UploadFile(dialog.File.Name, dialog.File.OpenRead());
}

private void UploadFile(string filename, Stream data)
{
    UriBuilder ub = new UriBuilder(UPLOAD_PATH);
    ub.Query = string.Format("filename={0}", filename);

    WebClient c = new WebClient();
    c.OpenWriteCompleted += (sender, e) =>
    {
        PushData(data, e.Result);
        e.Result.Close();
        data.Close();
    };
    c.OpenWriteAsync(ub.Uri, "Post");
}

private void PushData(Stream input, Stream output)
{
    byte[] buffer = new byte[4096];
    int bytesRead;

    while ((bytesRead = input.Read(buffer, 0, buffer.Length)) != 0)
    {
        output.Write(buffer, 0, bytesRead);
    }
}

$filepath = $_REQUEST['filename'];
$handle = fopen("php://input", "r");
$file = fopen($filepath,"w");

if($file != null && $handle != null)
{
        while ($data = fread($handle, 8192)) fwrite($file, $data);
        fclose($handle);
        fclose($file);
}

WebClient downloader = new WebClient();
downloader.OpenReadCompleted += new OpenReadCompletedEventHandler(onDownloadCompleted);
downloader.OpenReadAsync(new Uri(DLL_PATH, UriKind.Absolute));  

// Once the assembly is downloaded
private void onDownloadCompleted(object o, OpenReadCompletedEventArgs args)
{
    try
    {
        AssemblyPart ap = new AssemblyPart();
        Assembly assembly = ap.Load(args.Result);
        Object control = assembly.CreateInstance(CLASS_NAME);
    }
    catch (Exception e){}
}

If you are new to Silverlight networking,  remember to check out Network Security Access Restrictions in Silverlight.

// Create a request object
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(new Uri(POST_ADDRESS, UriKind.Absolute));
request.Method = "POST";
// don't miss out this
request.ContentType = "application/x-www-form-urlencoded";
request.BeginGetRequestStream(new AsyncCallback(RequestReady), request);  

// Sumbit the Post Data
void RequestReady(IAsyncResult asyncResult)
{
    HttpWebRequest request = asyncResult.AsyncState as HttpWebRequest;
    Stream stream = request.EndGetRequestStream(asyncResult);  

    // Hack for solving multi-threading problem
    this.Dispatcher.BeginInvoke(delegate()
    {
        // Send the post variables
        StreamWriter writer = new StreamWriter(stream);
        writer.WriteLine("key1=value1");
        writer.WriteLine("key2=value2");
        writer.Flush();
        writer.Close();  

        request.BeginGetResponse(new AsyncCallback(ResponseReady), request);
    });
}  

// Get the result  from the server
void ResponseReady(IAsyncResult asyncResult)
{
    HttpWebRequest request = asyncResult.AsyncState as HttpWebRequest;
    HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(asyncResult);  

    this.Dispatcher.BeginInvoke(delegate()
    {
        Stream responseStream = response.GetResponseStream();
        StreamReader reader = new StreamReader(responseStream);
        // get the result text
        string result = reader.ReadToEnd();
    });
}