/// <summary>Uploads data in a string to the specified resource, asynchronously.</summary>
/// <param name="webClient">The WebClient.</param>
/// <param name="address">The URI to which the data should be uploaded.</param>
/// <param name="method">The HTTP method that should be used to upload the data.</param>
/// <param name="data">The data to upload.</param>
/// <returns>A Task containing the data in the response from the upload.</returns>
public static Task <string> UploadStringTask(this WebClient webClient, Uri address, string method, string data)
{
// Create the task to be returned
var tcs = new TaskCompletionSource <string>(address);
// Setup the callback event handler
UploadStringCompletedEventHandler handler = null;
handler = (sender, e) => EAPCommon.HandleCompletion(tcs, e, () => e.Result, () => webClient.UploadStringCompleted -= handler);
webClient.UploadStringCompleted += handler;
// Start the async work
try
{
webClient.UploadStringAsync(address, method, data, tcs);
}
catch (Exception exc)
{
// If something goes wrong kicking off the async work,
// unregister the callback and cancel the created task
webClient.UploadStringCompleted -= handler;
tcs.TrySetException(exc);
}
// Return the task that represents the async operation
return(tcs.Task);
}
/// <summary>Downloads the resource with the specified URI to a local file, asynchronously.</summary>
/// <param name="webClient">The WebClient.</param>
/// <param name="address">The URI from which to download data.</param>
/// <param name="fileName">The name of the local file that is to receive the data.</param>
/// <returns>A Task that contains the downloaded data.</returns>
public static Task DownloadFileTask(this WebClient webClient, Uri address, string fileName)
{
// Create the task to be returned
var tcs = new TaskCompletionSource <object>(address);
// Setup the callback event handler
AsyncCompletedEventHandler handler = null;
handler = (sender, e) => EAPCommon.HandleCompletion(tcs, e, () => null, () => webClient.DownloadFileCompleted -= handler);
webClient.DownloadFileCompleted += handler;
// Start the async work
try
{
webClient.DownloadFileAsync(address, fileName, tcs);
}
catch (Exception exc)
{
// If something goes wrong kicking off the async work,
// unregister the callback and cancel the created task
webClient.DownloadFileCompleted -= handler;
tcs.TrySetException(exc);
}
// Return the task that represents the async operation
return(tcs.Task);
}
/// <summary>The core implementation of SendTask.</summary>
/// <param name="smtpClient">The client.</param>
/// <param name="userToken">The user-supplied state.</param>
/// <param name="sendAsync">
/// A delegate that initiates the asynchronous send.
/// The provided TaskCompletionSource must be passed as the user-supplied state to the actual SmtpClient.SendAsync method.
/// </param>
/// <returns></returns>
private static Task SendTaskCore(SmtpClient smtpClient, object userToken, Action <TaskCompletionSource <object> > sendAsync)
{
// Validate we're being used with a real smtpClient. The rest of the arg validation
// will happen in the call to sendAsync.
if (smtpClient == null)
{
throw new ArgumentNullException("smtpClient");
}
// Create a TaskCompletionSource to represent the operation
var tcs = new TaskCompletionSource <object>(userToken);
// Register a handler that will transfer completion results to the TCS Task
SendCompletedEventHandler handler = null;
handler = (sender, e) => EAPCommon.HandleCompletion(tcs, e, () => null, () => smtpClient.SendCompleted -= handler);
smtpClient.SendCompleted += handler;
// Try to start the async operation. If starting it fails (due to parameter validation)
// unregister the handler before allowing the exception to propagate.
try
{
sendAsync(tcs);
}
catch (Exception exc)
{
smtpClient.SendCompleted -= handler;
tcs.TrySetException(exc);
}
// Return the task to represent the asynchronous operation
return(tcs.Task);
}
