NEW ISSUE: Need some notion of "callback" address in conjunctionwith eventing

[Eric Johnson <eric@tibco.com>]

Title: Need some notion of "callback" address in conjunction with eventing

Target: Assembly 1.2 WD 01

Description:
For some uses of eventing, the point of using an event driven system is 
to decouple a collection of asynchronous interactions.

For example component A sends a message to component B, and A directs B 
to send a response to component C.

JMS, for example, includes the JMSReplyTo property.  This allows for 
asynchronous communications, and allows for the sender to dictate where 
the response should go, eliminating any direct architectural coupling of 
the receiver with the sender.

For the purposes of eventing in SCA, it is desirable on the "producer" 
side to send a message with a "reply" address pointing to some other 
consumer (or channel) on the component, or in the composite.

Likewise, on the consumer side, it may be useful to tie that consumer to 
an "unwired" producer, where that producer never gets wired to anything 
but rather sends to the destination received by the consumer.

Abstract proposal:

In the case of a producer expecting a "reply", change the "producer" on 
a component so that it includes something like a "@replyTo" attribute.

In the case of a producer sending a "reply", change the producer to have 
a "inReplyTo" attribute that names a particular consumer on the same 
component (@target attribute & @replyTo attribute not allowed)

-Eric.