  The use of cloud technology can offer significant savings for the deployment
of services, provided that the service is able to make efficient use of the
available virtual resources to meet service-level requirements. To avoid
software designs that scale poorly, it is important to make deployment
decisions for the service at design time, early in the development of the
service itself. ABS offers a formal, model-based approach which integrates the
design of services with the modeling of deployment decisions. In this paper, we
illustrate the main concepts of this approach by modeling a scalable pool of
workers with an auto-scaling strategy and by using the model to compare
deployment decisions with respect to client traffic with peak loads.
