public Relation Relation( Project project, String leftName, Domain left, Cardinality leftCardinality, String rightName, Domain right, Cardinality rightCardinality, Expression join) { RelationPK pk = new RelationPK(project.getId(), getNewID()); Relation relation = new Relation( pk, left.getId(), leftCardinality, right.getId(), rightCardinality, leftName, rightName, join); RelationServiceBaseImpl.getInstance().store(ctx, relation); return relation; }