Modelling QoS: Towards a UML Profile

In this paper, we present a conceptual object model for specifying Quality of Service (QoS) that forms a basis for a UML profile for QoS. The conceptual model is based on CQML, a lexical language for QoS specification. A QoS characteristic represents some aspect of the QoS of a system, service or resource that can be identified and quantified. A QoS statement expresses some QoS by constraining values of QoS characteristics. A QoS relation specifies the mutual obligation of an object and its environment with respect to QoS. These concepts are related to the UML meta-model in order to define a UML profile for QoS. An example from a Lecture on Demand (LoD) case study depicts how these concepts can be used during enterprise modelling and system design.