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Overview

This section presents all the concepts around Portlets:

 
Portlet life cycle

Each portlet in jPortlet exhibits the following portlet life cycle:

  1. When the Portal initializes, it initialized each Portlet by calling their init() method. Like Servlets, the only one instance of the Portlet is initianticiate and shared by all the users.
  2. The portal calls the service() method when the portlet is required to render it's content. During the life cycle of the portlet the service() method is typically called many times.
  3. When the portal is terminating, portlets are taken out of service, then destroyed with the destroy() method. Finally the portlet is garbage collected and finalized
In order to service users, each portlet is combine with a user session. When the user logs into the portal, the login() is called for each portlet, which allow each portlet to initialize the user portlet.
The portlet call the logout() method of each portlet to inform the the user's session is terminating.

 
Portlet modes

Portlet modes allow to display different user interfaces, depending of the task required. In jPortlet, there are 4 diplay modes which can be invoked by icons on the portlet title bar.
The following modes are supported by the Portlet API:

VIEW
This is the portlet's normal mode of operation.
HELP
If this mode is supported by a portlet, the portlet provides a help page for users to obtain more information about the portlet.
EDIT
If this mode is supported by a portlet, the portlet provides a page for users to customize the portlet for their own needs. For example, a portlet can provide a page for users to specify their location for obtaining local weather and events. Users must be logged into the portal to access edit mode.
CONFIGURE
If this mode is supported by a portlet, the portlet provides a page for portal administrators to configure a portlet for a user or group of users
The Portlet API provides methods for the portlet to determine the current or previous mode. All portlets must support the VIEW mode

 
Portlet states

Portlet states allow to change how the portlet window is displayed within the portal.
The following states are supported by the Portlet API:

NORMAL
The is when the portlet is arranged with other portlets
MAXIMIZED
When a portlet is maximized, it is displayed in the entire body of the portal, replacing the view of other portlets.
The Portlet API provides methods for the portlet to determine the current state.
By default, jPortlet always display the modes EDIT, CONFIGURE and HELP in MAXIMIZED state.

 
Portlet events

jPortlet supports 2 type of events:

Action events
When a user click a SUBMIT button in the HTML view of the portlet, this click is transformed to an ActionEvent that is generated and received by the Portlet's ActionListener
Message events
These event are generated when a portlet send a message to another portlet. Its a basic structure for inter-portlet communication. MessageEvent are received by the target Portlet's MessageListener

 
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