Applications play an important role in each eXo service, so it is necessary for you to further understand them. Portlets and gadgets are 2 main applications in eXo Platform, so 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. This section only focuses on how to develop a portlet and a gadget in the most basic manner. Also, you can refer to Portlet development and Gadget development to obtain the deeper knowledge.
This chapter includes the following main topics:
How to add an application (especially a portlet) to your site's pages.
Steps to create a gadget, create and apply resources in a gadget, and many methods of customizing a gadget.
Concept and mechanism of UI Extension framework which allows the customization and extensibility of eXo applications through simple plugins.