[jboss-dev-forums] [Design of JBoss Portal] - PortletContext and StateEvent design

[chris.laprun@jboss.com]

I think that we could simplify the current StateEvent/PortletContext handling in the context of state management of portlets. The current design, while based on subclasses, does not lend itself to polymorphism. 

For example, in FederatedInstanceContext:
if (event instanceof PortletClonedEvent)
  | {
  |    PortletClonedEvent pce = (PortletClonedEvent)event;
  |    PortletContext clonedContext = pce.getClonedContext();
  |    ctx.onStateEvent(new PortletClonedEvent(reference(clonedContext)));
  | }
  | else if (event instanceof PortletModifiedEvent)
  | {
  |    PortletModifiedEvent pce = (PortletModifiedEvent)event;
  |    PortletContext modifiedContext = pce.getModifiedContext();
  |    ctx.onStateEvent(new PortletModifiedEvent(reference(modifiedContext)));
  | }

I don't see the benefit of having such a split between different kinds of events. The above code could be simplified if StateEvent was taking on more responsibilities:
PortletContext portletContext = event.getPortletContext();
  | ctx.onStateEvent(new StateEvent(reference(portletContext)), event.getType());

In this new design, StateEvent would not be subclassed but contain a type field for these cases where the exact nature of the event needs to be known.

This would only work with a rework of PortletContext. I think that PortletContext should add a getState method. It's perfectly fine for a PortletContext to have an optional state (this is how WSRP works after all). We could keep the subclass to optimize memory usage and avoid to carry a byte[] on all PortletContexts even these which don't have a state. getState would return null if there is no state, StatefulPortletContext would override getState to return the state.

I think that these modifications would make dealing with state events easier and simplify our code.

What do people think?

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