⁠Chapter 36. Portlet Dynamic Module

As explained previously, portlet dependencies (including JavaScript files) can be declared in the gatein-resources.xml file, which forces declaration of portlet dependencies at packaging time when the corresponding war file is created.
The JSR286 specification provides a mechanism for modifying portal headers, which can also be used to load dependency JavaScript files. Although this mechanism is portable, it has the following drawbacks:
  • A script can be loaded multiple times, specially if two portlets in two different war files load the same scripts since the only way to identify a script is by its URL.
  • Scripts have to be loaded by the head section of the portal, impacting front-end performance.
The portal combines both approaches by allowing to create dynamic dependencies of a portlet at runtime, during the render phase of the portlet: 
​
​public void render(RenderRequest req, RenderResponse resp) throws PortletException, IOException {
​  resp.setProperty("org.gatein.javascript.dependency", "base");
​  resp.addProperty("org.gatein.javascript.dependency", "common");
​}
The code above is equivalent to the following declaration in the gatein-resources.xml file: 
​
​<portlet>
​  <name>MyPortlet</name>
​  <module>
​  <depends>
​    <module>base</module>
​  </depends>
​  <depends>
​    <module>common</module>
​  </depends>
​  </module>
​</portlet>
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