An implementation of the IMessageHandlerFactory interface is used to obtain an implementation of the IMessageHandler for the given message. Once a message is received on the work queue and instance of the relevant IMessageHandler is required to process the message. The actual message instance is passed to the factory to obtain the relevant IMessageHandler instance.
There is a MessageHandlerFactory abstract class that takes care of the pooling. You may want to derive from this class when implementation a new message handler factory but it is entirely up to you.
The DefaultMessageHandlerFactory implementation of the IMessageHandlerFactory interface will locate all loaded types that derive from IMessageHandler<> and as long as the type has a default constructor the message handler type will be available for use.
If you are using a dependency injection container and you would like dependencies injected into your handler the you would need a IMessageHandlerFactory implementation that is aware of the DI container. The CastleMessageHandlerFactory may serve as an example of how to achieve this.
IMessageHandler GetHandler(object message);
The method will return a new or pooled MessageHandler for the message.
void ReleaseHandler(IMessageHandler handler);
The method will return the MessageHandler to the pool if the message doesn’t iomplement IReusable or the message handler’s IReusable.IsReusable returns true the message handler will be pooled and re-used upon release. ; else it should be disposed of as necessary.
IEnumerable<Type> MessageTypesHandled { get; }
Returns a list of the message types that will be handled by the factory.