| Abstract: | Network communication services that can be configured to customize functionality provide significant advantages over monolithic versions, but can be difficult to construct if the services must also provide real‐time guarantees on message delivery. This paper describes how practical issues related to the combination of configurability and real time have been addressed in real‐time dependable (RTD) channels, a communication abstraction that has been prototyped using the Cactus system. The architecture and implementation of RTD channels are described, including facilities for translating an application's quality of service requirements into configuration‐specific resource requirements, and an admission control architecture that uses system‐wide information to determine whether sufficient resources exist to create new channels. In addition, the results of experiments that demonstrate that the desired channel properties—including real‐time guarantees—are provided for various configurations are presented. Finally, practical problems and lessons learned from implementing RTD channels on the general‐purpose MK 7.3 Mach operating system are discussed. Copyright © 2001 John Wiley & Sons, Ltd. |
