This is the pipeline doc entry point: http://portals.apache.org/jetspeed-2/guides/guide-pipeline.html I found useful informations about this also in this mailing list.
If it returns markup of portlet entity specified by id why that has to be one portlet on the page ? I don't know why but I think that this option opens interesting ways to assemble xml made by many portlet entities. If you need only one portlet entity markup then you can put only this portlet in your page. I used this feature to generate xml/rss markup of my portals from a single portlet. BTW .. If it is uneasy to use ajax and servlets with portlets in jetspeed2, can you point me the way how to periodically refresh portlet content to catch changes in database for an instance You can use: - AJAX - http page refresh meta tag (but this cause a whole page refresh) - a flash component that fetches periodically xml data from another source ROb