The need for Quality of Service support is significant in industrial and multimedia applications. However, it is often hard for software designers to deal with the low-level resources involved in the realization of QoS management. A wide range of technologies, programming languages and operating systems coexist, so it increases the difficulty for designers to build portable applications. Middleware architectures provide an abstract layer between applications and systems. They hide the technology heterogeneity and ease communications between distributed components. Following the Model Driven Architecture approach, but also using off-the-shelf libraries, the development process leading from the design to the implementation can be automated to take into account QoS requirements and to transpose them to a final piece of software. In this paper, we present a solution to model user-oriented QoS description, and the transformation steps that translate this information to low-level characteristics.