Portlet lifecycle

The portal, during the course of managing a portlet, passes the portlet through the following stages

1. Init
2. Process Action
3. Render
4. Destroy

There is one method in the Portlet interface for these stages. Right before a stage change occurs (e.g. when the portal is about to destroy a portlet), the portal notifies the portlet by invoking the appropriate method (the destroy() method for e.g.) on the Portlet Interface.

 

These are the possible state transitions

Init -> Process Action <-> Render -> Destroy

 

1. Init – Porlet is loaded and instantiated either on portlet container start or upon receipt of request for the portlet. Following this, the init() method on the portlet will be invoked. Portlets usually initialize expensive resources (connections for e.g.) at this time
2. Process Action & Render - Requests raised by portlets can from
1. Action URL: request fires processAction() method on portlet on which the URL resides and render() method on all the portlets. The portlet, in its processAction() method, updates its model. The render() method generates a view that indicates the current state of the model.
2. Render URL: request only fires render() method on all the portlets.
3. Destroy – Portal’s notice that the portlet is to be removed. Typically, a portlet will release all resources and persist any yet-to-be-persisted state/model.