Enabling two-phase rendering for a portlet

By default, two-phase rendering is turned off. To enable two-phase rendering for a portlet, you must update the portlet.xml deployment descriptor for the portlet.

Edit the portlet.xml file for the portlet. Add the following entry to the file:

<portlet>
    ...
    <container-runtime-option>
        <name>javax.portlet.renderHeaders</name>
        <value>true</value>
    </container-runtime-option>
</portlet>