General framework for the description of QoS in UML

UML is useful for modeling object-oriented systems, their behavior and interaction. However, UML currently does not support the modeling of quality of service (QoS) criteria, such as the reliability and accuracy (i.e., quality). A QoS framework provides support to ensure consistency in modeling various qualities of service. It supports a general categorization of different kinds of QoS; including QoS that are fixed at design time as well as ones that are managed dynamically. And it supports the integration of different categories of QoS for the purpose of QoS modeling of system aspects. Frequently the behavior of a system component is functionally correct, but the result it generates is nevertheless unacceptable because the result does not meet some QoS criteria. One way to enhance the capability of the system to deliver results of acceptable quality is to use flexible components that adapt their behavior depending on the resources available and the QoS required.