Portal Layer
Within the portal layer, the user interfaces and processes are provided in a role-based manner using the Work Center and Control Center concepts.
The smallest visible unit in the portal is an iView (portlet), the basic element of a portal page. It is a small application that retrieves information, processes it, and displays it in the portal. You can use iViews to integrate your composite applications into the portal pages.
More information:
Integrating Applications
into the Portal