Subscription

It'd be nice to allow a component to logically subscribe to the output of a component to support 1-many distribution - i.e. like JMS topics.

Right now a component can output a one-way and not really care where it goes - letting the NMR do the routing. So we should provide a 'service subscription' model on a component to be able to do 1-many routing.

e.g.

each component's ActivationSpec could have a collection of Subscription objects, each subscription object could be something like...

class Subscription {
  QName serviceName
  QName interfaceName
  QName operationName
  String endpoint

  Filter filter
}

Maybe we could include an SubscriptionBroadcaster interface so that you could implement both a parallel broadcaster and serial broadcaster.

And programatically maybe we should provide an interface to allow you to add a subscription from a JBI component/service.

This might be part of the ComponentContext, this might provide a simple method such as,

componentContext.registerSubscription(ServiceEndPoint serviceEndPoint)

A few questions:

• Are all subscriptions immutable?
• Do we provide the ability to add subscription query language like JMS subscription? An interesting question is mapping a JMS property to a NormalizedMessage property?
• Subscription persistence