/// <summary>
/// Receives a single message from the service.
/// </summary>
/// <param name="webSocket">The connected WebSocket on which to listen for the message.</param>
/// <param name="requestId">The request ID associated with the message.</param>
/// <param name="token">A task cancellation token.</param>
/// <returns>
/// A Task representing the asynchronous operation whose result will contain the message
/// received from the service upon task completion.
/// </returns>
private async Task <SpeechServiceMessage> ReceiveMessageAsync(WebSocket webSocket, string requestId, CancellationToken token)
{
WebSocketReceiveResult result = null;
ArraySegment <byte> buffer = new ArraySegment <byte>(new byte[8192]);
using (var stream = new MemoryStream())
{
// Read incoming message into a MemoryStream (potentially in multiple chunks)
do
{
try
{
result = await webSocket.ReceiveAsync(buffer, token);
}
catch (OperationCanceledException)
{
continue;
}
stream.Write(buffer.Array, buffer.Offset, result.Count);
}while (result != null && !result.EndOfMessage);
token.ThrowIfCancellationRequested();
stream.Seek(0, SeekOrigin.Begin);
if (result.MessageType == WebSocketMessageType.Text)
{
using (var reader = new StreamReader(stream, Encoding.UTF8))
{
var message = reader.ReadToEnd();
var speechServiceMessage = SpeechServiceMessage.Deserialize(message);
if (speechServiceMessage.RequestId == requestId)
{
return(speechServiceMessage);
}
}
}
else if (result.MessageType == WebSocketMessageType.Close)
{
if (webSocket.CloseStatus.HasValue)
{
// Translate the close status to a ConversationError and raise it
this.RaiseTranslatedError(webSocket.CloseStatus.Value, webSocket.CloseStatusDescription);
}
return(null);
}
// No other message types are supported
throw new NotSupportedException();
}
}
/// <summary>
/// Sends a message to the service.
/// </summary>
/// <param name="message">The message to send.</param>
/// <param name="requestId">The request id associated with the message.</param>
/// <param name="token">A task cancellation token.</param>
/// <returns>A Task representing the asynchronous operation.</returns>
private async Task SendMessageAsync(SpeechServiceMessage message, string requestId, CancellationToken token)
{
message.Headers["X-Timestamp"] = DateTime.UtcNow.ToString("yyyy-MM-ddTHH:mm:ss.fffK");
message.Headers["X-RequestId"] = requestId;
await this.webSocket.SendAsync(
new ArraySegment <byte>(message.GetBytes()),
message is SpeechServiceBinaryMessage?WebSocketMessageType.Binary : WebSocketMessageType.Text,
true,
token);
}