Recently, it is realized that in distributed applications, software engineers must also consider Quality of Service (QoS), which is a measure of the non-functional properties of services along multiple dimensions, such as reliability, security, scalability, performance (response time, for instance), etc. when designing component connections. In this talk we will introduce an operational model for reasoning about QoS properties of the exogenous channel-based coordination language Reo. We will investigate the quality aspects of Reo when the specification of channels and component interfaces can involve non-functional requirements. We introduce Quantified Constraint Automata (QCA) as an extension to ordinary constraint automata with QoS values added as additional labels to the individual transitions indicating their use of resources, costs, reliabilities, etc. when executed.