/// <summary>
/// Processes the hub's incoming method calls.
/// </summary>
protected override Task OnReceived(IRequest request, string connectionId, string data)
{
HubRequest hubRequest = _requestParser.Parse(data, _serializer);
// Create the hub
HubDescriptor descriptor = _manager.EnsureHub(hubRequest.Hub,
_counters.ErrorsHubInvocationTotal,
_counters.ErrorsHubInvocationPerSec,
_counters.ErrorsAllTotal,
_counters.ErrorsAllPerSec);
IJsonValue[] parameterValues = hubRequest.ParameterValues;
// Resolve the method
MethodDescriptor methodDescriptor = _manager.GetHubMethod(descriptor.Name, hubRequest.Method, parameterValues);
if (methodDescriptor == null)
{
// Empty (noop) method descriptor
// Use: Forces the hub pipeline module to throw an error. This error is encapsulated in the HubDispatcher.
// Encapsulating it in the HubDispatcher prevents the error from bubbling up to the transport level.
// Specifically this allows us to return a faulted task (call .fail on client) and to not cause the
// transport to unintentionally fail.
IEnumerable <MethodDescriptor> availableMethods = _manager.GetHubMethods(descriptor.Name, m => m.Name == hubRequest.Method);
methodDescriptor = new NullMethodDescriptor(descriptor, hubRequest.Method, availableMethods);
}
// Resolving the actual state object
var tracker = new StateChangeTracker(hubRequest.State);
var hub = CreateHub(request, descriptor, connectionId, tracker, throwIfFailedToCreate: true);
return(InvokeHubPipeline(hub, parameterValues, methodDescriptor, hubRequest, tracker)
.ContinueWithPreservedCulture(task => hub.Dispose(), TaskContinuationOptions.ExecuteSynchronously));
}
private Task InvokeHubPipeline(IHub hub,
IJsonValue[] parameterValues,
MethodDescriptor methodDescriptor,
HubRequest hubRequest,
StateChangeTracker tracker)
{
// TODO: Make adding parameters here pluggable? IValueProvider? ;)
HubInvocationProgress progress = GetProgressInstance(methodDescriptor, value => SendProgressUpdate(hub.Context.ConnectionId, tracker, value, hubRequest), Trace);
Task <object> piplineInvocation;
try
{
var args = _binder.ResolveMethodParameters(methodDescriptor, parameterValues);
// We need to add the IProgress<T> instance after resolving the method as the resolution
// itself looks for overload matches based on the incoming arg values
if (progress != null)
{
args = args.Concat(new[] { progress }).ToList();
}
var context = new HubInvokerContext(hub, tracker, methodDescriptor, args);
// Invoke the pipeline and save the task
piplineInvocation = _pipelineInvoker.Invoke(context);
}
catch (Exception ex)
{
piplineInvocation = TaskAsyncHelper.FromError <object>(ex);
}
// Determine if we have a faulted task or not and handle it appropriately.
return(piplineInvocation.ContinueWithPreservedCulture(task =>
{
if (progress != null)
{
// Stop ability to send any more progress updates
progress.SetComplete();
}
if (task.IsFaulted)
{
return ProcessResponse(tracker, result: null, request: hubRequest, error: task.Exception);
}
else if (task.IsCanceled)
{
return ProcessResponse(tracker, result: null, request: hubRequest, error: new OperationCanceledException());
}
else
{
return ProcessResponse(tracker, task.Result, hubRequest, error: null);
}
})
.FastUnwrap());
}
public HubRequest Parse(string data, JsonSerializer serializer)
{
var deserializedData = serializer.Parse <HubInvocation>(data);
var request = new HubRequest();
request.Hub = deserializedData.Hub;
request.Method = deserializedData.Method;
request.Id = deserializedData.Id;
request.State = GetState(deserializedData);
request.ParameterValues = (deserializedData.Args != null) ? deserializedData.Args.Select(value => new JRawValue(value)).ToArray() : _emptyArgs;
return(request);
}
private Task ProcessResponse(StateChangeTracker tracker, object result, HubRequest request, Exception error)
{
var hubResult = new HubResponse
{
State = tracker.GetChanges(),
Result = result,
Id = request.Id,
};
if (error != null)
{
_counters.ErrorsHubInvocationTotal.Increment();
_counters.ErrorsHubInvocationPerSec.Increment();
_counters.ErrorsAllTotal.Increment();
_counters.ErrorsAllPerSec.Increment();
var hubError = error.InnerException as HubException;
if (_enableDetailedErrors || hubError != null)
{
var exception = error.InnerException ?? error;
hubResult.StackTrace = _isDebuggingEnabled ? exception.StackTrace : null;
hubResult.Error = exception.Message;
if (hubError != null)
{
hubResult.IsHubException = true;
hubResult.ErrorData = hubError.ErrorData;
}
}
else
{
hubResult.Error = String.Format(CultureInfo.CurrentCulture, Resources.Error_HubInvocationFailed, request.Hub, request.Method);
}
}
Trace.TraceVerbose("Sending hub invocation result to connection {0} using transport {1}", Transport.ConnectionId, Transport.GetType().Name);
return(Transport.Send(hubResult));
}
private Task SendProgressUpdate(string connectionId, StateChangeTracker tracker, object value, HubRequest request)
{
var hubResult = new HubResponse
{
State = tracker.GetChanges(),
Progress = new { I = request.Id, D = value },
// We prefix the ID here to ensure old clients treat this as a hub response
// but fail to lookup a corresponding callback and thus no-op
Id = "P|" + request.Id,
};
return(Connection.Send(connectionId, hubResult));
}