/// <summary>
/// Starts the <see cref="Connection"/>.
/// </summary>
/// <param name="transport">The transport to use.</param>
/// <returns>A task that represents when the connection has started.</returns>
public Task Start(IClientTransport transport)
{
lock (_startLock)
{
_connectTask = TaskAsyncHelper.Empty;
_disconnectCts = new CancellationTokenSource();
if (!ChangeState(ConnectionState.Disconnected, ConnectionState.Connecting))
{
return(_connectTask);
}
_monitor = new HeartbeatMonitor(this, _stateLock);
_transport = transport;
_connectTask = Negotiate(transport);
}
return(_connectTask);
}
private Task Negotiate(IClientTransport transport)
{
_connectionData = OnSending();
return(transport.Negotiate(this, _connectionData)
.Then(negotiationResponse =>
{
VerifyProtocolVersion(negotiationResponse.ProtocolVersion);
ConnectionId = negotiationResponse.ConnectionId;
ConnectionToken = negotiationResponse.ConnectionToken;
_disconnectTimeout = TimeSpan.FromSeconds(negotiationResponse.DisconnectTimeout);
_totalTransportConnectTimeout = TransportConnectTimeout + TimeSpan.FromSeconds(negotiationResponse.TransportConnectTimeout);
// Default the beat interval to be 5 seconds in case keep alive is disabled.
var beatInterval = TimeSpan.FromSeconds(5);
// If we have a keep alive
if (negotiationResponse.KeepAliveTimeout != null)
{
_keepAliveData = new KeepAliveData(TimeSpan.FromSeconds(negotiationResponse.KeepAliveTimeout.Value));
_reconnectWindow = _disconnectTimeout + _keepAliveData.Timeout;
beatInterval = _keepAliveData.CheckInterval;
}
else
{
_reconnectWindow = _disconnectTimeout;
}
_monitor = new HeartbeatMonitor(this, _stateLock, beatInterval);
return StartTransport();
})
.ContinueWithNotComplete(() => Disconnect()));
}
private Task Negotiate(IClientTransport transport)
{
// Captured and used by StartNegotiation to track attempts
var negotiationAttempts = 0;
Task CompleteNegotiation(NegotiationResponse negotiationResponse)
{
ConnectionId = negotiationResponse.ConnectionId;
ConnectionToken = negotiationResponse.ConnectionToken;
_disconnectTimeout = TimeSpan.FromSeconds(negotiationResponse.DisconnectTimeout);
_totalTransportConnectTimeout = TransportConnectTimeout + TimeSpan.FromSeconds(negotiationResponse.TransportConnectTimeout);
// Default the beat interval to be 5 seconds in case keep alive is disabled.
var beatInterval = TimeSpan.FromSeconds(5);
// If we have a keep alive
if (negotiationResponse.KeepAliveTimeout != null)
{
_keepAliveData = new KeepAliveData(TimeSpan.FromSeconds(negotiationResponse.KeepAliveTimeout.Value));
_reconnectWindow = _disconnectTimeout + _keepAliveData.Timeout;
beatInterval = _keepAliveData.CheckInterval;
}
else
{
_reconnectWindow = _disconnectTimeout;
}
Monitor = new HeartbeatMonitor(this, _stateLock, beatInterval);
return(StartTransport());
}
Task StartNegotiation()
{
return(transport.Negotiate(this, _connectionData)
.Then(negotiationResponse =>
{
VerifyProtocolVersion(negotiationResponse.ProtocolVersion);
if (negotiationResponse.ProtocolVersion.Equals("2.0"))
{
if (!string.IsNullOrEmpty(negotiationResponse.Error))
{
throw new StartException(string.Format(Resources.Error_ErrorFromServer, negotiationResponse.Error));
}
if (!string.IsNullOrEmpty(negotiationResponse.RedirectUrl))
{
if (!negotiationResponse.RedirectUrl.EndsWith("/"))
{
negotiationResponse.RedirectUrl += "/";
}
// Update the URL based on the redirect response and restart the negotiation
Url = negotiationResponse.RedirectUrl;
if (!string.IsNullOrEmpty(negotiationResponse.AccessToken))
{
// This will stomp on the current Authorization header, but that's by design.
// If the server specified a token, that is expected to overrule the token the client is currently using.
Headers["Authorization"] = $"Bearer {negotiationResponse.AccessToken}";
}
negotiationAttempts += 1;
if (negotiationAttempts >= MaxRedirects)
{
throw new InvalidOperationException(Resources.Error_NegotiationLimitExceeded);
}
return StartNegotiation();
}
}
return CompleteNegotiation(negotiationResponse);
})
.ContinueWithNotComplete(() => Disconnect()));
}
_connectionData = OnSending();
return(StartNegotiation());
}
