This ebook is the first authorized digital version of Kernighan and Ritchie's 1988 classic, The C Programming Language (2nd Ed.). One of the best-selling programming books published in the last fifty years, "K&R" has been called everything from the "bible" to "a landmark in computer science" and it has influenced generations of programmers. Available now for all leading ebook platforms, this concise and beautifully written text is a "must-have" reference for every serious programmers digital library.

As modestly described by the authors in the Preface to the First Edition, this "is not an introductory programming manual; it assumes some familiarity with basic programming concepts like variables, assignment statements, loops, and functions. Nonetheless, a novice programmer should be able to read along and pick up the language, although access to a more knowledgeable colleague will help."

The C programming language

Mobile ad hoc networks (MANETs) represent complex distributed systems that comprise wireless mobile nodes that can freely and dynamically self-organize into arbitrary and temporary, ‘‘ad-hoc’’ network topologies, allowing people and devices to seamlessly internetwork in areas with no pre-existing communication infrastructure, e.g., disaster recovery environments. Ad hoc networking concept is not a new one, having been around in various forms for over 20 years. Traditionally, tactical networks have been the only communication networking application that followed the ad hoc paradigm. Recently, the introduction of new technologies such as the Bluetooth, IEEE 802.11 and Hyperlan are helping enable eventual commercial MANET deployments outside the military domain. These recent evolutions have been generating a renewed and growing interest in the research and development of MANET. This paper attempts to provide a comprehensive overview of this dynamic field. It first explains the important role that mobile ad hoc networks play in the evolution of future wireless technologies. Then, it reviews the latest research activities in these areas, including a summary of MANETs characteristics, capabilities, applications, and design constraints. The paper concludes by presenting a set of challenges and problems requiring further research in the future. � 2003 Elsevier B.V. All rights reserved.

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Mobile ad hoc networking: imperatives and challenges

Originating from basic research conducted in the 1970's and 1980's, the parallel and distributed simulation field has matured over the last few decades. Today, operational systems have been fielded for applications such as military training, analysis of communication networks, and air traffic control systems, to mention a few. The article gives an overview of technologies to distribute the execution of simulation programs over multiple computer systems. Particular emphasis is placed on synchronization (also called time management) algorithms as well as data distribution techniques.

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Parallel and Distributed Simulation Systems

1. Introduction 2. Background 3. Performance evaluation process algebra 4. Modelling study: multi-server multi-queue systems 5. Notions of equivalence 6. Isomorphism and weak isomorphism 7. Strong bisimilarity 8. Strong equivalence 9. Conclusions Bibliography Index.

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A Compositional Approach to Performance Modelling

Over the last decade, a lot of research has been directed toward integrating performance analysis into the software development process. Traditional software development methods focus on software correctness, introducing performance issues later in the development process. This approach does not take into account the fact that performance problems may require considerable changes in design, for example, at the software architecture level, or even worse at the requirement analysis level. Several approaches were proposed in order to address early software performance analysis. Although some of them have been successfully applied, we are still far from seeing performance analysis integrated into ordinary software development. In this paper, we present a comprehensive review of recent research in the field of model-based performance prediction at software development time in order to assess the maturity of the field and point out promising research directions.

Model-based performance prediction in software development: a survey

Software components can give rise to several kinds of architectural mismatches when assembled together in order to form a software system. A formal description of the architecture of the resulting component-based software system may help to detect such architectural mismatches and to single out the components that cause the mismatches. In this article, we concentrate on deadlock-related architectural mismatches arising from three different causes that we identify: incompatibility between two components due to a single interaction, incompatibility between two components due to the combination of several interactions, and lack of interoperability among a set of components forming a cyclic topology. We develop a process algebra-based architectural description language called PADL, which deals with all three causes through an architectural compatibility check and an architectural interoperability check relying on standard observational equivalences. The adequacy of the architectural compatibility check is assessed on a compressing proxy system, while the adequacy of the architectural interoperability check is assessed on a cruise control system. We then address the issue of scaling the architectural compatibility and interoperability checks to architectural styles through an extension of PADL. The formalization of an architectural style is complicated by the presence of two degrees of freedom within the set of instances of the style: variability of the internal behavior of the components and variability of the topology formed by the components. As a first step towards the solution of the problem, we propose an intermediate abstraction called architectural type, whose instances differ only for the internal behavior of their components. We define an efficient architectural conformity check based on a standard observational equivalence to verify whether an architecture is an instance of an architectural type. We show that all the architectures conforming to the same architectural type possess the same compatibility and interoperability properties.

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Architecting families of software systems with process algebras

Today's concomitant needs for higher computing power and reliability has increased the relevance of multiple-processor fault-tolerant systems. Multiple functional units improve the raw performance (throughput, response time, etc.) of the system, and, as units fail, the system may continue to function albeit with degraded performance. Such systems and other fault-tolerant systems are not adequately characterized by separate performance and reliability measures. A composite measure for the performance and reliability of a fault-tolerant system observed over a finite mission time is analyzed. A Markov chain model is used for system state-space representation, and transient analysis is performed to obtain closed-form solutions for the density and moments of the composite measure. Only failures that cannot be repaired until the end of the mission are modeled. The time spent in a specific system configuration is assumed to be large enough to permit the use of a hierarchical model and static measures to quantify the performance of the system in individual configurations. For a multiple-processor system, where performance measures are usually associated with and aggregated over many jobs, this is tantamount to assuming that the time to process a job is much smaller than the time between failures. An extension of the results to general acyclic Markov chain models is included.

Analysis of a composite performance reliability measure for fault-tolerant systems

Fault-tolerant computer systems may be evaluated by calculating their cumulative performance (e.g., number of processes jobs) over a finite mission time. A method for calculating the cumulative performance distribution assuming that the system fault-repair behavior can be modeled by a homogeneous Markov process is described. The method proposed for calculating the probability distribution of the accumulated reward over a finite mission is applicable to models of repairable and nonrepairable systems. The related solution algorithm shows a low polynomial computational complexity. The mathematical model is introduced, and the results already presented in the literature are surveyed. A comprehensive analysis of the time and space complexity of the proposed solution algorithm is presented. A numerical example is given. >

On evaluating the cumulative performance distribution of fault-tolerant computer systems

Systems of heterogeneous parallel processing are studied such as arising in parallel programs executed on distributed systems. A lower and an upper bound model are suggested to obtain secure lower and upper bounds on the performance of these systems. The bounding models are solved by using a matrix-geometric algorithmic approach. Formal proofs of the bounds are provided along with error bounds on the accuracy of the bounds. These error bounds in turn are reduced to simple computational expressions. Numerical results are included. The results are of interest for application to arbitrary fork-join models with parallel heterogeneous processors and synchronization.

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Bound performance models of heterogeneous parallel processing systems

This paper focuses on the design and performance evaluation of a new mechanism, named Distributed Contention Control (DCC), for the adaptive contention reduction in LAN networks that utilize random access MAC protocols. The proposed mechanism could be executed on the top of a preexistent access protocol, with no additional overhead introduced. Specifically, we consider the IEEE 802.11 wireless LAN (WLAN). The DCC mechanism requires a simple and rough estimate of the contention level, and this can be achieved by estimating any parameter, directly connected with the amount of contention on the shared channel. The main characteristics of the proposed mechanism are represented by its simplicity, integration with the Standard, complete distribution, absence of overheads, and prompt reaction to changes in the network congestion. The protocol automatically adapts to the network congestion by monitoring the channel contention level through the estimation of the contention parameter. In this paper we show that the information needed for the contention estimation is already available to a 802.11 station, with no additional costs. Simulation experiments to evaluate the performance of an IEEE 802.11 WLAN, with and without the DCC mechanism, have been carried out. Results confirmed the effectiveness of the DCC mechanism in improving the performance, stability, and congestion reaction of the IEEE 802.11 access scheme. The DCC mechanism also provides a simple way to implement a distributed priority mechanism.

Lorenzo Donatiello

Papers

Architecting families of software systems with process algebras

Analysis of a composite performance reliability measure for fault-tolerant systems

On evaluating the cumulative performance distribution of fault-tolerant computer systems

Bound performance models of heterogeneous parallel processing systems

Design and performance evaluation of a distributed contention control(DCC) mechanism for IEEE 802.11 wireless local area networks