Issue #26: Should we allow handleEvents() to return markup?

[Subbu Allamaraju <subbu@bea.com>]

I was tasked with starting a discussion on whether there is a need for 
handleEvents to return markup to the Consumer. Here it goes.

Regards

Subbu

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Use Case: Portlet P raises an event. Producer A handles this event for 
Portlet A, but does not return any events. Producer B handles this event 
and returns another event, which the Consumer dispatches to Portlet C on 
Producer C. Consumer then sends getMarkup requests to Producers A, B and 
C to get markup for portlets A, B, and C respectively.

Current Model: Consumer will have to make three extra network round 
trips to get the markup.

Proposed Model:

[UpdateResponse] = handleEvents (RegistrationContext, PortletContext,
                                  RuntimeContext, UserContext,
                                  navigationalState, portletStateChange,
                                  mode, windowState, events[]

The Consumer SHOULD discard the returned MarkupContext if it sends 
additional events to the same portlet.

Note that, if we decide to let handleEvents return MarkupContext, we can 
reuse the UpdateResponse structure.

With this change, Producer A and Producer B can return MarkupContext 
with handleEvents response, and the Consumer can to use this 
MarkupContext and avoid extra network round-trips.