Recently, dynamic behaviors in embedded system for ubiquitous environment and service-oriented system have needed a dynamic coupling metric to evaluate the quality of the software system more accurately. The embedded systems are designed by a component-based system and the component-based system is designed by one object-oriented. Therefore, coupling between the classes in the object-oriented model are brought into relief more clearly. But, in spite of a great deal of study and effort, most coupling metrics between classes suggest metrics that measure the coupling based on a static dependency relationship. In this paper, we propose a dynamic coupling metric in order to measure the coupling accurately between classes allowing the dynamic property in the object level. In addition, we prove the theoretical soundness of the proposed metric by the axioms of Briand et at. and suggest the accuracy of the proposed metric through a comparison with conventional metrics.

Advances in network technology and computing power have inspired the emergence of high-performance cluster computing systems. While cluster management and hardware highavailability tools are readily available, practical and easily deployable fault-tolerant systems have not been successfully adopted commercially. We present a fault-tolerant system, Multiple fault-tolerant MPI over Myrinet (M3), that differs in notable respects from other proposed fault-tolerant systems in the literature. M3 is built on top of Myrinet since it is regarded as one of the best solutions for highperformance networks and is widely used in cluster computing systems because it can provide a high-speed switching network that is an inevitable ingredient in interconnecting clusters of workstations or PCs. M^3 is a user-transparent checkpointing system for multiple fault-tolerant MPI implementation that is primarily based on the coordinated checkpointing protocol. M3 supports three critical functionalities that are necessary for faulttolerance: a light-weight failure detection mechanism, dynamic process management that includes process migration, and a consistent checkpoint and recovery mechanism. The features of M are that it requires no modifications of application code and that it preserves much of the high performance characteristics of Myrinet. This paper describes the architecture of M3, its detailed design principles and comprehensive implementation issues. We also propose practical solutions for those involved in constructing highly available cluster systems for parallel programming systems. Experimental results substantiate our assertion that M3 can be a good candidate for practically deployable fault-tolerant systems in very-large and high-performance Myrinet clusters and that its protocol can be applied to a wide variety of parallel communication libraries without difficulty.