1994 Reports

QuAL: Quality Assurance Language

Florissi, Patrícia Gomes Soares

Distributed multimedia applications are sensitive to the Quality of Services (QoS) provided by their computing and communication environment. For example, scheduling of processing activities or network queueing delays may cause excessive jitter in a speech stream, rendering it difficult to understand. It is thus important to establish effective technologies to ensure delivery of QoS required by distributed multimedia applications. This proposal presents a new language for the development of distributed multimedia applications: Quality Assurance Language (QuAL). QuAL abstractions allow the specification of QoS constraints expected from the underlying computing and communication environment. QuAL specifications are compiled into run time components that monitor the actual QoS delivered. Upon QoS violations, application provided exception handlers are signaled to act upon the faulty events. Language level abstractions of QoS shelter programs from the heterogeneity of underlying infrastructures. This simplifies the development and maintenance of multimedia applications and promotes their portability and reuse. QuAL generates Management Information Bases (MIBs) that contain QoS statistics per application. Such MIBs may be used to integrate application level QoS management into standard network management frameworks.