Service Independence, Service Components and the Network Resource Model

This contribution which presents work done within EURESCOM Project P103 "Evolution of the Intelligent Network" addresses the question of service independence, defines the notion of Service Component and discusses the interaction between the two domains of a telecommunications system, indicated as "Service Domain" and "Network Domain", in terms of a shared knowledge, represented by the Network Resource Model. A service can be viewed as a set of elements, termed Service Components, and, optionally, some 'glue" logic that binds them together. Using concepts of set theory, we can say that a set intersection between services will yield the elements that are common to all services, to some services but not to all, or to only one specific service; this structures Service Components in a hierarchy of service independence. Service Components can be described in terms of Role Models, by OORAM language: this methodology also offers guidelines to extract Service Components from an overall high-level description of a service. An example of Service Component with a high degree of service independence is Connection Management. This component is of particular interest also because it lies at the "boundary" between the Service Domain, comprising all functionalities, concerned with the provision of an end-user service, and the Network Domain, compnising the functionalities related to the use of network resources: the "core" of the interface between these two domains is offered by Connection Management. The analysis of Connection Management shows that the interaction between Service Domain and Network Domain has to be based on a shared knowledge between the two, and that the most significant element of this knowledoe is the information model of network resources. This In Network Resource Model has to capture those aspects of the network that are relevant for services, hiding as much as possible of the underlying complexity. Some emerging resource modelling approaches are analysed.