For those who asked for a leaner sample of Opereffa, the wiki has a simple tutorial, based on a class submitted into SVN.
It performs the very basic task of entering data using an archetype, saving it to DB, loading it back and printing values to console.
Pablo, and few others who asked for such an example will hopefully find this helpful.
http://www.openehr.org/wiki/display/projects/Simple+tutorial+for+saving+and+loading+data
Kind regards
Seref