Control theory provides solid foundations for developing reliable and scalable feedback control for software sys- tems. In particular, there exist well-established feedback controllers for common problems, however, the state- of-the-art approaches for designing self-adaptation for legacy software systems do not primarily support classical feedback control and its integration is usually engineered manually. In this paper, we revisit the Znn.com case study and we present a new implementation based on classical feedback controllers. We show how these controllers can be easily integrated into software systems through control theory centric architecture models and domain-specific modeling support. We also provide an assessment of the resulting properties, quality attributes and limitations.