Creating Portals

Due to the growing complexity of web sites, portals and portlets are experiencing serious growth. Portals help reduce complexity by allowing the dynamic aggregation and display of diverse content in a single web page. Portal components are pluggable parts called portlets. To be "pluggable" portlets and portals must satisfy standards. The authors of this book, all but one employees of IBM, created these standards: Java Portlet Specification JSR 168 and Web Services for Remote Portlets (WSRP).
Portals can serve an enterprise in a variety of ways. Read about key use cases and then learn more about then on Liferay's website. This article contains some realy usefull diagrams.
Usefull sources of information: 

• Portlet 2.0 API 2.0 API 
• Apache Portals Bridges
  Portlet Bridge Portlet is a web clipping proxy portlet that allows web application be hosted as portlets. The web clipping can be customized using XSLT.
  The Struts Bridge allows Struts and Struts Tiles applications to be run as JSR-168 compliant Portlets.PortletBridge Portlet project creates a JSR-168 Portlet that can proxy and rewrite content from a downstream web site.
  http://www.portletbridge.org/
• Portlets and Apache Portals explains how to develop JSR 168 and WSRP compliant portlets and how to test and deploy these portlets on Apache open source software. Richly illustrated with useful code examples. By the creators of WSRP and JSR 168 portlet standards. 
• Jetspeed-2 is an Open Portal Platform and Enterprise Information Portal, written entirely in open source under the Apache license in Java and XML and based on open standards. Jetspeed has been fully conformant to the Java Portlet 2.0 Standard since release 2.2.0 in May 2009. All releases prior, such as the 2.1.x releases, are conformant to the first Java Portlet Specification, the Java Portlet 1.0 Standard.
• Liferay Portal is an enterprise web platform for building business solutions that deliver immediate results and long-term value.
  Runs PHP, Ruby, Python, Grails and other lightweight scripting technologies within a robust Java framework.
  Content & Document Management with Microsoft Office® integration.
  You can download the open source version of Liferay Portal for free from Liferay’s
  web site.(See here...)
  Alternatively, Liferay sells an Enterprise Edition of Liferay Portal. This is a commercially
  available version of the product that comes with support and a hot-patching system
  for bug fixes and performance improvements.
  Standards JSR-286 (Portlet 2.0)
  Layout on Liferay
• Sample chapter of "Life Ray In action"
• This tutorial shows you how to create a basic JSR 168 Portlet with Websphere.
•  Install Liferay IDE on Eclipse Indigo
• Lutece is a portal engine which allows you to easily create your websites or intranets based upon HTML, XML... content.
  Lutece provides a user friendly interface for portal management and therefore no specific technical skills are required.
  This software is implemented in Java and based on widely used libraries and frameworks : Spring, Freemarker, Lucene, Ehcache, Jakarta-commons, PDFBox, ..Lutece is free and Open-Source : it is distributed under a BSD-like license.