QoS-aware software components

The next generation of complex software systems will be highly distributed, component-based, and service-oriented. They will need to operate in unattended mode, possibly in hostile environments, and they'll be composed of many "replaceable" components discoverable at runtime. Moreover, they will have to run on a multitude of unknown and heterogeneous hardware and network platforms. Three major requirements for such systems are performance, availability, and security. Performance requirements imply that these systems must be adaptable and self-configurable to changes in workload intensity. Availability and security requirements suggest that these systems also must adapt and reconfigure themselves to withstand attacks and failures. This paper focuses specifically on QoS requirements for performance and describes the framework for QoS-aware distributed applications.