Question

I have this code:

public static String Download(string address) {
    WebClient client = new WebClient();
    Uri uri = new Uri(address);

    // Specify a progress notification handler.
    client.DownloadProgressChanged += (_sender, _e) => {
        // 
    };

    // ToDo: DownloadStringCompleted event

    client.DownloadStringAsync(uri);
}

Instead of having the rest of my code execute in the DownloadStringCompleted event handler when the download is complete, can I somehow Join this Async request? It will be housed in another thread (doing it this way so I have access to the download progress). I know that DownloadStringAsync can take a second parameter; an object called userToken in the manual. Could this be of use? Thank you,

Answer 1

You could use a manual reset event:

class Program
{
    static ManualResetEvent _manualReset = new ManualResetEvent(false);

    static void Main()
    {
        WebClient client = new WebClient();
        Uri uri = new Uri("http://www.google.com");

        client.DownloadProgressChanged += (_sender, _e) =>
        {
            //
        };

        client.DownloadStringCompleted += (_sender, _e) => 
        {
            if (_e.Error == null)
            {
                // do something with the results
                Console.WriteLine(_e.Result);
            }
            // signal the event
            _manualReset.Set();
        };

        // start the asynchronous operation
        client.DownloadStringAsync(uri);

        // block the main thread until the event is signaled
        // or until 30 seconds have passed and then unblock
        if (!_manualReset.WaitOne(TimeSpan.FromSeconds(30)))
        {
            // timed out ...
        }
    }
}