Writing and debugging distributed programs can be difficult. When a program is working, it may be difficult to achieve reasonable execution performance. A cause of these difficulties is a lack of tools for the programmer.

Conventional programs have a single stream of execution. Distributed programs expand on this notion, having multiple streams of execution that interact with each other. This expansion increases the complexity of a program's behavior. Existing program monitors do not provide enough information to deal with all of the problems of a distributed computing environment. This paper is concerned with the development of a programming tool for Berkeley UNIX whose goal is to characterize the performance of distributed programs.

Fieldbus Technology (FT) is an enabling platform that is becoming the preferred choice for the next generation real-time automation and control solutions. This book incorporates a selection of research and development papers. Topics covered include: history and background, contemporary standards, underlying architecture, comparison between different Fieldbus systems, applications, latest innovations, new trends as well as issues such as compatibility, interoperability, and interchangeability.

Writing distributed programs is difficult for at least two reasons. The first reason is that distributed computing environments present new problems caused by asyn- chrony, independent time bases, and communications delays. The second reason is that there is a lack of tools available to help the programmer understand the program he/she has written. The tools we use for single machine environments do not easily generalize to a distributed environment. There has been only limited success with previous systems that have tried to help the programmer in developing, debugging, and measuring distributed pro- grams. To better understand distributed programs we have: specified a model for distributed computation, developed a measurement methodology from this model, constructed tools to implement the measurements, and developed data analysis techniques to obtain useful results from the measurements. The most important feature of the models, methodology, and tools is consistency between the programmer's view, the computation model, the measurement methodology, and the analysis. This consistency has resulted in several benefits. The first is a simplicity of structure throughout the measurement and analysis tools. The second benefit is the ease of obtaining useful information about a program's behavior. The model of distributed programs defines the two basic actions of a program to be computation and communication. Our research focuses on the communications performed by a program. the measurement model is based on the monitoring of communications between the parts of a program. Given out definition of a program, monitoring communications complete- ly encapsulates the behavior of a computation. From the measurement model, we have con- structed tools to measure distributed programs for two working operating systems, UNIX and DEMOS/MP. These measurement tools provide data on the interactions between the parts of a distributed program. We have developed a number of analysis techniques to provide information from the data collected . We can report communications statistics on message counts, queue lengths, and message waiting times. We can perform more complex analyses, such as measuring the amount of parallelism in the execution of a distributed program. The analyses also include detecting paths of causality through the parts of the distributed program. The measurement tools and analyses can be structured so that results can be fed back into the operating system to help with scheduling decisions.

Distributed real-time systems (DRTSs) are used in a wide range of applications, including command and control systems, flight control systems, robotics, patient monitoring systems, and many others. This volume provides an overview of various systematic approaches to the testing and debugging of DRTSs—tasks that typically consume 50% to 70% of a new system's development costs. Distributed Real-Time Systems covers both the theoretical and practical issues involved in monitoring, visualization, and analysis methodology for verifying and debugging DRTSs. It describes in detail how to overcome timing verification difficulties and improve system performance and reliability. Complete with many carefully worked-out examples, as well as dozens of illustrations, this timely and accessible work Explains real-world debugging approaches—proposed or tested—using static analysis or dynamic analysis with or without monitoring Features step-by-step instructions for design implementation in hardware and software, detecting timing errors and their causes, graphical debugging methods, and more Covers numerous analytical techniques, including timed Petri nets, temporal logic, timed state transition systems, timed process algebra, and synchronous programming languages Makes distributed systems analysis accessible through examples such as a distributed telephone switching system and a fault-tolerant distributed system Reviews many relevant professional papers and current research work The joint product of four leaders in the field, Distributed Real-Time Systems is an important text and reference for electrical and software engineers, graduate students, and anyone involved in computer and data processing technology.