private async Task<NegotiationResponse> Negotiate(Uri url, HttpClient httpClient, ILogger logger)
{
try
{
// Get a connection ID from the server
logger.EstablishingConnection(url);
var urlBuilder = new UriBuilder(url);
if (!urlBuilder.Path.EndsWith("/"))
{
urlBuilder.Path += "/";
}
urlBuilder.Path += "negotiate";
using (var request = new HttpRequestMessage(HttpMethod.Post, urlBuilder.Uri))
{
SendUtils.PrepareHttpRequest(request, _httpOptions);
using (var response = await httpClient.SendAsync(request))
{
response.EnsureSuccessStatusCode();
return await ParseNegotiateResponse(response, logger);
}
}
}
catch (Exception ex)
{
logger.ErrorWithNegotiation(url, ex);
throw;
}
}
public Task StartAsync(Uri url, IDuplexPipe application, TransferFormat transferFormat, IConnection connection)
{
if (transferFormat != TransferFormat.Text)
{
throw new ArgumentException($"The '{transferFormat}' transfer format is not supported by this transport.", nameof(transferFormat));
}
_application = application;
Log.StartTransport(_logger, transferFormat);
var startTcs = new TaskCompletionSource <object>(TaskContinuationOptions.RunContinuationsAsynchronously);
var sendTask = SendUtils.SendMessages(url, _application, _httpClient, _httpOptions, _transportCts, _logger);
var receiveTask = OpenConnection(_application, url, startTcs, _transportCts.Token);
Running = Task.WhenAll(sendTask, receiveTask).ContinueWith(t =>
{
Log.TransportStopped(_logger, t.Exception?.InnerException);
_application.Output.Complete(t.Exception?.InnerException);
_application.Input.Complete();
return(t);
}).Unwrap();
return(startTcs.Task);
}
public Task StartAsync(Uri url, IDuplexPipe application, TransferMode requestedTransferMode, IConnection connection)
{
if (requestedTransferMode != TransferMode.Binary && requestedTransferMode != TransferMode.Text)
{
throw new ArgumentException("Invalid transfer mode.", nameof(requestedTransferMode));
}
connection.Features.Set <IConnectionInherentKeepAliveFeature>(new ConnectionInherentKeepAliveFeature(_httpClient.Timeout));
_application = application;
Mode = requestedTransferMode;
Log.StartTransport(_logger, Mode.Value);
// Start sending and polling (ask for binary if the server supports it)
_poller = Poll(url, _transportCts.Token);
_sender = SendUtils.SendMessages(url, _application, _httpClient, _httpOptions, _transportCts, _logger);
Running = Task.WhenAll(_sender, _poller).ContinueWith(t =>
{
Log.TransportStopped(_logger, t.Exception?.InnerException);
_application.Output.Complete(t.Exception?.InnerException);
_application.Input.Complete();
return(t);
}).Unwrap();
return(Task.CompletedTask);
}
public Task StartAsync(Uri url, Channel <byte[], SendMessage> application, TransferMode requestedTransferMode, string connectionId)
{
if (requestedTransferMode != TransferMode.Binary && requestedTransferMode != TransferMode.Text)
{
throw new ArgumentException("Invalid transfer mode.", nameof(requestedTransferMode));
}
_application = application;
Mode = requestedTransferMode;
_connectionId = connectionId;
_logger.StartTransport(_connectionId, Mode.Value);
// Start sending and polling (ask for binary if the server supports it)
_poller = Poll(url, _transportCts.Token);
_sender = SendUtils.SendMessages(url, _application, _httpClient, _transportCts, _logger, _connectionId);
Running = Task.WhenAll(_sender, _poller).ContinueWith(t =>
{
_logger.TransportStopped(_connectionId, t.Exception?.InnerException);
_application.Out.TryComplete(t.IsFaulted ? t.Exception.InnerException : null);
return(t);
}).Unwrap();
return(Task.CompletedTask);
}
private async Task <NegotiationResponse> Negotiate(Uri url, HttpClient httpClient, ILogger logger)
{
try
{
// Get a connection ID from the server
Log.EstablishingConnection(logger, url);
var urlBuilder = new UriBuilder(url);
if (!urlBuilder.Path.EndsWith("/"))
{
urlBuilder.Path += "/";
}
urlBuilder.Path += "negotiate";
using (var request = new HttpRequestMessage(HttpMethod.Post, urlBuilder.Uri))
{
// Corefx changed the default version and High Sierra curlhandler tries to upgrade request
request.Version = new Version(1, 1);
SendUtils.PrepareHttpRequest(request, _httpOptions);
using (var response = await httpClient.SendAsync(request))
{
response.EnsureSuccessStatusCode();
return(await ParseNegotiateResponse(response, logger));
}
}
}
catch (Exception ex)
{
Log.ErrorWithNegotiation(logger, url, ex);
throw;
}
}
public Task StartAsync(Uri url, Channel <byte[], SendMessage> application, TransferMode requestedTransferMode, IConnection connection)
{
if (requestedTransferMode != TransferMode.Binary && requestedTransferMode != TransferMode.Text)
{
throw new ArgumentException("Invalid transfer mode.", nameof(requestedTransferMode));
}
_application = application;
Mode = TransferMode.Text; // Server Sent Events is a text only transport
_logger.StartTransport(Mode.Value);
var sendTask = SendUtils.SendMessages(url, _application, _httpClient, _httpOptions, _transportCts, _logger);
var receiveTask = OpenConnection(_application, url, _transportCts.Token);
Running = Task.WhenAll(sendTask, receiveTask).ContinueWith(t =>
{
_logger.TransportStopped(t.Exception?.InnerException);
_application.Writer.TryComplete(t.IsFaulted ? t.Exception.InnerException : null);
return(t);
}).Unwrap();
return(Task.CompletedTask);
}
private async Task OpenConnection(IDuplexPipe application, Uri url, TaskCompletionSource <object> startTcs, CancellationToken cancellationToken)
{
Log.StartReceive(_logger);
var request = new HttpRequestMessage(HttpMethod.Get, url);
SendUtils.PrepareHttpRequest(request, _httpOptions);
request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("text/event-stream"));
HttpResponseMessage response;
try
{
response = await _httpClient.SendAsync(request, HttpCompletionOption.ResponseHeadersRead, cancellationToken);
response.EnsureSuccessStatusCode();
startTcs.TrySetResult(null);
}
catch (Exception ex)
{
Log.TransportStopping(_logger);
startTcs.TrySetException(ex);
return;
}
using (var stream = await response.Content.ReadAsStreamAsync())
{
var pipeOptions = new PipeOptions(pauseWriterThreshold: 0, resumeWriterThreshold: 0);
var pipelineReader = StreamPipeConnection.CreateReader(pipeOptions, stream);
var readCancellationRegistration = cancellationToken.Register(
reader => ((PipeReader)reader).CancelPendingRead(), pipelineReader);
try
{
while (true)
{
var result = await pipelineReader.ReadAsync();
var input = result.Buffer;
if (result.IsCanceled || (input.IsEmpty && result.IsCompleted))
{
Log.EventStreamEnded(_logger);
break;
}
var consumed = input.Start;
var examined = input.End;
try
{
Log.ParsingSSE(_logger, input.Length);
var parseResult = _parser.ParseMessage(input, out consumed, out examined, out var buffer);
switch (parseResult)
{
case ServerSentEventsMessageParser.ParseResult.Completed:
Log.MessageToApp(_logger, buffer.Length);
await _application.Output.WriteAsync(buffer);
_parser.Reset();
break;
case ServerSentEventsMessageParser.ParseResult.Incomplete:
if (result.IsCompleted)
{
throw new FormatException("Incomplete message.");
}
break;
}
}
finally
{
pipelineReader.AdvanceTo(consumed, examined);
}
}
}
catch (OperationCanceledException)
{
Log.ReceiveCanceled(_logger);
}
finally
{
readCancellationRegistration.Dispose();
_transportCts.Cancel();
Log.ReceiveStopped(_logger);
}
}
}
private async Task Poll(Uri pollUrl, CancellationToken cancellationToken)
{
Log.StartReceive(_logger);
try
{
while (!cancellationToken.IsCancellationRequested)
{
var request = new HttpRequestMessage(HttpMethod.Get, pollUrl);
SendUtils.PrepareHttpRequest(request, _httpOptions);
HttpResponseMessage response;
try
{
response = await _httpClient.SendAsync(request, cancellationToken);
}
catch (OperationCanceledException)
{
// SendAsync will throw the OperationCanceledException if the passed cancellationToken is canceled
// or if the http request times out due to HttpClient.Timeout expiring. In the latter case we
// just want to start a new poll.
continue;
}
response.EnsureSuccessStatusCode();
if (response.StatusCode == HttpStatusCode.NoContent || cancellationToken.IsCancellationRequested)
{
Log.ClosingConnection(_logger);
// Transport closed or polling stopped, we're done
break;
}
else
{
Log.ReceivedMessages(_logger);
var stream = new PipeWriterStream(_application.Output);
await response.Content.CopyToAsync(stream);
await _application.Output.FlushAsync();
}
}
}
catch (OperationCanceledException)
{
// transport is being closed
Log.ReceiveCanceled(_logger);
}
catch (Exception ex)
{
Log.ErrorPolling(_logger, pollUrl, ex);
throw;
}
finally
{
// Make sure the send loop is terminated
_transportCts.Cancel();
Log.ReceiveStopped(_logger);
}
}
private async Task OpenConnection(Channel <byte[], SendMessage> application, Uri url, CancellationToken cancellationToken)
{
_logger.StartReceive();
var request = new HttpRequestMessage(HttpMethod.Get, url);
SendUtils.PrepareHttpRequest(request, _httpOptions);
request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("text/event-stream"));
var response = await _httpClient.SendAsync(request, HttpCompletionOption.ResponseHeadersRead, cancellationToken);
var stream = await response.Content.ReadAsStreamAsync();
var pipelineReader = StreamPipeConnection.CreateReader(new PipeOptions(_memoryPool), stream);
var readCancellationRegistration = cancellationToken.Register(
reader => ((IPipeReader)reader).CancelPendingRead(), pipelineReader);
try
{
while (true)
{
var result = await pipelineReader.ReadAsync();
var input = result.Buffer;
if (result.IsCancelled || (input.IsEmpty && result.IsCompleted))
{
_logger.EventStreamEnded();
break;
}
var consumed = input.Start;
var examined = input.End;
try
{
var parseResult = _parser.ParseMessage(input, out consumed, out examined, out var buffer);
switch (parseResult)
{
case ServerSentEventsMessageParser.ParseResult.Completed:
_application.Writer.TryWrite(buffer);
_parser.Reset();
break;
case ServerSentEventsMessageParser.ParseResult.Incomplete:
if (result.IsCompleted)
{
throw new FormatException("Incomplete message.");
}
break;
}
}
finally
{
pipelineReader.Advance(consumed, examined);
}
}
}
catch (OperationCanceledException)
{
_logger.ReceiveCanceled();
}
finally
{
readCancellationRegistration.Dispose();
_transportCts.Cancel();
stream.Dispose();
_logger.ReceiveStopped();
}
}
private async Task Poll(Uri pollUrl, CancellationToken cancellationToken)
{
_logger.StartReceive(_connectionId);
try
{
while (!cancellationToken.IsCancellationRequested)
{
var request = new HttpRequestMessage(HttpMethod.Get, pollUrl);
SendUtils.PrepareHttpRequest(request, _httpOptions);
HttpResponseMessage response;
try
{
response = await _httpClient.SendAsync(request, cancellationToken);
}
catch (OperationCanceledException)
{
// SendAsync will throw the OperationCanceledException if the passed cancellationToken is canceled
// or if the http request times out due to HttpClient.Timeout expiring. In the latter case we
// just want to start a new poll.
continue;
}
response.EnsureSuccessStatusCode();
if (response.StatusCode == HttpStatusCode.NoContent || cancellationToken.IsCancellationRequested)
{
_logger.ClosingConnection(_connectionId);
// Transport closed or polling stopped, we're done
break;
}
else
{
_logger.ReceivedMessages(_connectionId);
// Until Pipeline starts natively supporting BytesReader, this is the easiest way to do this.
var payload = await response.Content.ReadAsByteArrayAsync();
if (payload.Length > 0)
{
while (!_application.Writer.TryWrite(payload))
{
if (cancellationToken.IsCancellationRequested || !await _application.Writer.WaitToWriteAsync(cancellationToken))
{
return;
}
}
}
}
}
}
catch (OperationCanceledException)
{
// transport is being closed
_logger.ReceiveCanceled(_connectionId);
}
catch (Exception ex)
{
_logger.ErrorPolling(_connectionId, pollUrl, ex);
throw;
}
finally
{
// Make sure the send loop is terminated
_transportCts.Cancel();
_logger.ReceiveStopped(_connectionId);
}
}