Portlet coordination

We can use either the events mechanism or the public render parameters mechanism to coordinate portlets within a portal.

JSR 286 defines these two mechanisms as follows:

• Events: Loose-coupling of portlets during action phase.

• Public render parameters: Share of view state between portlets.

The WebSphere Application Server portlet container supports both concepts with one exception. The wiring of events on a portal level is not supported.

To make use of the public render parameters on a portal page defined with the aggregation tag library, you must explicitly declare the portal scope:

<%@ taglib uri="http://ibm.com/portlet/aggregation" prefix="portlet" %>
<%@ page isELIgnored ="false"%>

<!-- define portal scope for public render parameters -->
<portlet:scope>
  <portlet:portlet context="/simpleportlet" portletname="SimplePortlet1" windowId="id1"/
  <portlet:portlet context="/simpleportlet2" portletname="SimplePortlet2" windowId="id2"/>
</portlet:scope>

<portlet:init portletURLPrefix="/my-webapp-context/my-portal-jsp-url-pattern/">
<!-- insert the portlets here, wrapped with the html markup -->
...
   <portlet:insert url="simpleportlet/SimplePortlet1" windowId="id1" titleVar="portlettitle_1"/>
...
   <portlet:insert url="simpleportlet2/SimplePortlet2" windowId="id2" titleVar="portlettitle_1"/>
...
</portlet:init>

The public render parameters are only visible to the portlet windows mentioned within this defined scope. This condition assumes, as a prerequisite, that the corresponding portlets have also declared support for a given public render parameter in their portlet.xml file, according to the JSR 286 specification:

...
   <portlet>
      <portlet-name>portlet_name1</portlet-name>
       ...
       <supported-public-render-parameter>foo</supported-public-render-parameter>
   </portlet>
   <portlet>
      <portlet-name>portlet_name2</portlet-name>
       ...
       <supported-public-render-parameter>foo</supported-public-render-parameter>
   </portlet>
   <public-render-parameter>
       <identifier>foo</identifier>
       <qname xmlns:x="http://example.com/params">x:foo2</qname>
   </public-render-parameter>
...

Related concepts

Portlet container

Portlet aggregation using JSP

Portlet URL security

Supported optional features of the JSR-286 Portlet Specification

Related tasks

Task overview: Managing portlets

Configure portlet fragment caching

Portlet container settings

Aggregation tag library attributes

Related information:

JSR 286 Portlet Specification
Exploiting the WAS V6.1 portlet container: Part 2: Going beyond the basics
What's new in the Java Portlet Specification V2.0 (JSR 286)?