Some thoughts on inter portlet communication through backing beans

[Marcio E Miranda <Ma...@fastsearch.com>]

Hi,

 

I'd like to share some thoughts we had while developing a JSR 168
portlet application using JSF, specifically regarding inter portlet
communication, and get some feedback from you.

 

The portlets we developed were highly coupled; an event in a portlet
would trigger actions in different portlets, which might in turn trigger
additional actions on additional portlets; so we needed some sort of
inter portlet communication. Each portal vendor implements its own
portlet event mechanism (at least most of them), but we didn't want to
be tied to any proprietary solution, so we had to think of something
else.

 

Our solution was to enable inter portlet communication through backing
beans. In our application, each portlet has a JSF view backed by a
backing bean. The backing bean is created by JSF (managed bean) and
stored in the session. An initializer class, implementing
HttpSessionListener, creates what we called an EventBroker and stores it
in the user session. Every backing bean interested in participating in
the event mechanism must extend an abstract class called
EventAwareBackingBean. This class implements HttpSessionBindingListener,
so when the bean is bound to the session (done by JSF), the valueBound
method will give it a reference to the Event broker and call the
createListeners method. The createListeners method is an abstract method
that should return a collection of Listeners that will be registered
with the Event broker (each Listener will call some method in the
backing bean).

 

When a backing bean wishes to fire an event, it should create an event
implementing an interface (passing in the argument the source backing
bean and a payload) and pass it to the Event broker. The broker will
check all registered listeners and notify those which accept that event.
When the listener is notified, it will call a method (defined in the
listener) on the backing bean which has registered it.

 

We have tested this implementation on Liferay with My Faces and it is
working fine. Do you see potential problems with this approach? Any
feedback is appreciated.  

 

______________________
Marcio Miranda