Gang,
I have been thinking a lot about the QI-310, and I conclude that I am
not at all happy with current situation.
I often find myself with needing a "activation task", for instance to
connect (and maintain connectivity) to an MQ feed, and like that out
of the way of the actual service's purpose. But since such Mixin would
not have any public methods, nor private mixin methods, Qi4j will
simply not include such Mixin in the service. The work-around is to
have Activatable in the public composite interface, but we have
introduced special meaning to Activatable at Mixin level.
I would like to suggest a series of incompatible changes in this space;
1. Activatable is removed completely.
2. Introduce @Activation and @Passivation annotation, which can be
placed on any number of methods of any Mixin, as long as the method
has zero arguments, or Qi4j annotated arguments that can be resolved,
such as @Structure and @Service.
3. Add custom "Activators" as a concept, which can only be assigned
to a Service at bootstrap, and is not partOf the composite itself. For
instance;
module.addService( MyService.class).withActivators(
MqConnection.class, PubSubConnection.class );
and possibly also allow activators to be instantiated at assembly
module.addService( MyService.class).withActivators( new
MqConnection(host,port) );
The activator implements an interface which provides access to all
internal bits of the ServiceComposite, probably via a new interface
called ServiceContext;
public interface ServiceActivator<T> {
void activate( T instance, ServiceContext<T> context );
void passivate( T instance, ServiceContext<T> context );
}
I have not yet worked out what the ServiceContext is exactly, but it
should have methods for easy access to methods, annotations, service
configuation (incl, on-the-fly creation, validation and modification),
private mixins and more.
WDYAT?
Cheers
--
Niclas Hedhman, Software Developer
http://www.qi4j.org - New Energy for Java
I live here; http://tinyurl.com/3xugrbk
I work here; http://tinyurl.com/6a2pl4j
I relax here; http://tinyurl.com/2cgsug
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