A portlet mode indicates the function a portlet is performing. Normally, portlets perform
different tasks and create different content depending on the function they are currently
performing. A portlet mode advises the portlet what task it should perform and what
content it should generate. When invoking a portlet, the portlet container provides the
current portlet mode to the portlet. Portlets can programmatically change their portlet
mode when processing an action request.
The Portlet Specification defines three portlet modes, VIEW, EDIT, and HELP.
A design tip can be put all business logic related to VIEW mode in a method called doView(), and business logic related to the configuration of the application in a doEdit() method, and help-related logic in a doHelp()