The DDS specification provides fine-grained control over the real-time behaviour, dependability, and performance of DDS applications by means of a rich set of QoS Policies. The challenge for many DDS users is that the specifications explains very clearly how each QoS allows to control very specific aspects of data distribution yet it provides no hints on how different QoS should be composed to control complex properties such as the consistency model, or to impose end-to-end real-time scheduling decision.