A number of research studies show that the operating system has a substantial influence on communication delay in distributed environments. Thus, in order to provide applications with end-to-end QoS guarantees, network resource management alone is not sufficient. To date, several approaches have been proposed, addressing QoS issues from the end-system point of view. However, while network QoS provisioning has achieved a good level of standardization, no standard proposals exist for the end-systems. We claim that a single architectural model, taking into account both end-system and network resource management is needed. In this paper we propose a QoS architecture, which extends the concept of service differentiation inside the end-system. A system prototype has been developed and tested on a Diffserv network scenario. The prototype incorporates a priority-based communication mechanism inside the end-point operating system and a local marker so to implement an appropriate mapping between...