Quality of Service Negotiation for Distributed, Dynamic Real-Time Systems

Dynamic, distributed, real-time systems control an environment that varies widely without any time-invariant statistical or deterministic characteristic, are spread across multiple loosely-coupled computers, and must control the environment in a timely manner. In order to ensure that such a system meets its timeliness guarantees, there must be a means to monitor and maintain the quality of service in the system. The QoS manager is a monitoring and diagnosis system for real-time paths, collections of time-constrained and precedence-constrained applications. These applications may be distributed across multiple, heterogeneous computers and networks. This paper addresses the QoS negotiation features of the QoS manager and its interaction with the middleware resource manager. The major contributions of the paper are the negotiation algorithms and protocol that minimize the impact on the other paths' QoS while maximizing the unhealthy path's QoS. The approach and algorithms for QoS negotiation are presented.