The RelationFactory is a factory cacheing all Relations loaded by Vortex. All instances of Relation have to be instanciated through the RelationFactory. The factory keeps a cache of the Relation instances which will be returned. If no chache exists a new instance of Relation class is created, put into cache and returned.
Get a Relation from the factory
$relation = RelationFactory::getRelation( $idrelation );
Clear the factory cache (this you very seldom want to do)