JBoss.orgCommunity Documentation
It is important to understand distinctions between gadgets and portlets. Portlets are user interface components that provide fragments of markup code from the server side, while gadgets generate dynamic web content on the client side. With Gadgets, small applications can be built quickly, and mashed up on the client side using the lightweight Web-Oriented Architecture (WOA) technologies, like REST or RSS.
For more information on how to develop gadgets and portlets, see the Portlet development and Gadget development sections.