Monitoring distributed real-time activities in DCOM

Abstract

Object-oriented frameworks have become a key element in the design of distribution systems. They make the existence of the physical and operating system level resources transparent to the designer and provide the abstract view of the distributed systems as a set of objects that interact by invoking well-defined interfaces of each other. Easy reuse of existing components, location transparency and implementation hiding are the main ingredients of such frameworks that simplify the task of designing distributed systems drastically. It is desirable to take advantage of these benefits when designing distributed real-time systems, too. However, this goal conflicts with the essential need to consider the allocation of system resources when real-time requirements must be met. Here, system level resource issues such as execution times on CPUs, thread switches, occurrence of interrupts, and message delays are of primary interest. Our approach to solve this dilemma is to allow and support the designer of distributed real-time object-oriented applications to become aware of system level resources. We present a monitoring tool JewelDC that allows monitoring of distribution activities (i.e. nested sequences of object invocations) in a distributed object-oriented framework. Distributed activities are visualized at the abstract object level while simultaneously revealing their use of system level resources. The tool has been implemented for DCOM on Microsoft Windows NT 4.0.