How are portlets rendered / ordered / layed out in Plone?

Question

I'm trying to change the global ordering of the portlets in my Plone site. I've searched the Plone source code but I can't find the code that actually iterates through and renders the portlets, for example the 'plone.rightcolumn' and 'plone.leftcolumn' content providers. Where is that code?

Answer 1

First check http://developer.plone.org/reference_manuals/old/portlets/rendered.html for technical details (imho this is still up-to-date)

The PortletRetriever (plone.portlets) collects and orders all portlet assignments.

The PortletManagerRenderer uses the informations of the retriever to render the column

Also have a look at the code of Solgema.PortletsManager they improved the PortletRetriever, this is exactly what you want to do.