From the software engineering perspective, the notion of Service Oriented Architecture (SOA) has been receiving significant attention within the software design and development community. This attention has led to the proliferation of conflicting characterizations of SOA, resulting in an ambiguous understanding of SOA entities and relationships among them. To achieve a common understanding, OASIS and SeCSE propose reference models that introduce a comprehensive ontology for modeling software services around the well known service-oriented interaction pattern. However OASIS and SeCSE models abstract the actual interaction pattern runtime support, which is generally provided by a Service Oriented Middleware (SOM). In this paper we propose a reference model for architecting SOM solutions over next generation networking environment and evaluate it by designing a conforming lower-level model for the SOM developed for the PLASTIC project.