The "QoS query service" for improved quality-of-service decision making in CORBA

We present the quality-of-service query service (QQS) a CORBA service which provides quality-of-service-related "decisions" for the configuration and parameterization of CORBA applications. Applications and services query QQS for those QoS-related decisions, and input data into QQS, so that evaluators have the necessary information to execute their decision-making algorithms. QQS consists of a database, a registration, naming and dramatic-loading facility for evaluators, and a registration and dynamic-loading facility for data collectors. The data model underlying the database is a QoS-oriented data model specially designed for QQS, such that a maximum amount of relevant queries and evaluators fit into QQS. This paper describes the motivation, design, implementation and use of the QoS query service.