The accelerated development of Internet and mobile devices has lead to new QoS-demanding distributed applications and new QoS-providing communication services, particularly at the transport level. The diversity of transport services and underlying networks environments asks for a novel design of the transport layer, able to provide in a transparent and autonomous way the most adapted service to the application. With this aim in mind, this paper presents a methodology based on a model-driven architecture (MDA) approach specialized using ontologies. It provides a QoS ontology model integrating standard and QoS-oriented transport services, protocols and mechanisms aimed at characterizing the entities, concepts and relationships composing this complex domain. This semantic model is intended to facilitate the integration of future mechanisms and protocols extensions. It offers the required properties to implement the knowledge base of an autonomic manager enabling transport service discovery, selection and composition based on application requirements and network constraints.