public async Task StartServer(CancellationToken token = default(CancellationToken))
{
// Get any available handlers
var handlers = new List <HandlerRegistration>();
Type[] handlerTypes = _handlerFactory.GetAllHandlerTypes();
foreach (Type handlerType in handlerTypes)
{
// Try to get the IHandleMessage<T> interface from the handlerType
var handlerInterfaces = handlerType.IsMessageHandlerInterface()
? new Type[] { handlerType } // The handlerType itself is already IHandleMessage<T>
: handlerType.GetMessageHandlerInterfaces().ToArray(); // The handlerType should implement IHandleMessage<T> at least once
if (handlerInterfaces.Length == 0)
{
throw new InvalidOperationException($"The handler Type {handlerType.Name} is not a message handler");
}
// Get the message Type T from IHandleMessage<T> and create a handler registration by invoking the static factory method
// on HandlerRegistration with the appropriate type arguments
foreach (Type handlerInterface in handlerInterfaces)
{
Type messageType = handlerInterface.GenericTypeArguments.Single();
var handler =
(HandlerRegistration)HandlerRegistrationFactoryMethod.MakeGenericMethod(handlerType, messageType).Invoke(this, null);
handlers.Add(handler);
}
}
// Nothing to do if no handlers
if (handlers.Count == 0)
{
return;
}
// Get the unique message FullNames amongst the handlers and use those as the topic name to subscribe to
Dictionary <string, List <HandlerRegistration> > handlersByTopic = handlers.GroupBy(h => h.MessageDescriptor.FullName)
.ToDictionary(g => g.Key, g => g.ToList());
// Subscribe to all topics
Subscription[] subscriptions = await Task.WhenAll(handlersByTopic.Select(kvp => Subscribe(kvp.Key, kvp.Value, token)))
.ConfigureAwait(false);
// Kick off a background task to pull messages off the transport for each subscription and dispatch the messages
_runningServer = Task.Run(() => RunServer(subscriptions, _cancelRunningServer.Token), _cancelRunningServer.Token);
}