Extensible Contract Broker for Performance Differentiation

We denote as self-properties the control a system exerts on itself autonomically to achieve and maintain quality-of service (QoS). Our focus is in external, non-intrusive approaches and in this paper we focus mainly timeliness objectives. The self-adaptation process must be guided by the specification of the desired qualities. In this paper we describe the design of a contract-broker (C-Broker) architecture for implementing quality-of-service features and Self- properties. We also show how basic QoS features were implemented in C-Broker. Our approach involved dynamic XML specifications for required parameters.