如何从Silverlight中的HttpWebRequest.BeginGetRequestStream中更新我的UI

private void UpdateUI()
{
    // 更新UI的代码
}

private void RequestCallback(IAsyncResult result)
{
    // 处理请求回调
    // ...

    // 更新UI
    Dispatcher.BeginInvoke(() => UpdateUI());
}

private void SendRequest()
{
    // 发送请求
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://example.com");
    request.BeginGetRequestStream(RequestCallback, null);
}

public static readonly DependencyProperty MyPropertyProperty =
    DependencyProperty.Register("MyProperty", typeof(string), typeof(MyControl), null);

public string MyProperty
{
    get { return (string)GetValue(MyPropertyProperty); }
    set { SetValue(MyPropertyProperty, value); }
}

private void RequestCallback(IAsyncResult result)
{
    // 处理请求回调
    // ...

    // 更新UI
    MyProperty = "新的值";
}

private void SendRequest()
{
    // 发送请求
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://example.com");
    request.BeginGetRequestStream(RequestCallback, null);
}