In an EGL portlet application, the EGL logic parts control portlets. These parts allow you to put data in a Portal and get input from users. EGL portlet development follows the EGL web application programming model, and differs only in the ways noted in this section.
WebSphere® Portal Server is a content aggregator. It uses programs called portlet to process user requests and generate dynamic content. The portal acts as a container for the portlets, managing the lifecycle of, and providing various services to, the portlets and combining their output into a single web page.
Each page of a portal is divided into "windows" that display the dynamic content generated by a single portlet. Portlet windows have two user modifiable properties, mode and window state.
A portlet mode is an indication of the function that the portlet will perform to produce specific content or perform a certain task. Common portlet modes are View, Edit, and Help.
All portlets are required to provide View mode support. In this mode, portlets generate their normal dynamic content. For example, you can have a portlet that displays the local weather in the portlet window.
Portlet can also be displayed in Edit mode. In our weather portlet example, if we had displayed the portlet in Edit mode, it would wait for the user to enter the local zip code in order to customize the weather display. Each user is able to provide this customization data, which means that the portlet will display different data depending on who is logged in. Edit mode support is optional.
Help mode causes the portlet to display information on the use of the portlet. The help can be a single screen displaying help for the entire portlet, or may be more context specific. Help mode support is optional.
The window state of a portlet is an indicator of the amount of page real estate that the portlet will occupy. Portlets can have three possible states: normal, maximized, and minimized.
The normal window state indicates that the portlet may be sharing the page with any either any number of other portlets. Because the portlet window might be small, the portlet author might want to limit the amount of page space that the portlet requires. For instance, in the example weather portlet, we can choose to limit its display to the temperature and a graphic that indicates the current weather conditions.
A maximized window state can show that the portlet will either be the only one that is portlet displayed or that it will be given more space than the other portlets on the page. If we designate the weather portlet as maximized then it could display a local forecast information for multiple days.
When minimized, the portlet should display little or no information. The container might choose not to render the portlet at all, which means that it is not likely a minimized portlet will display during page rendering.