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Reviewer: Shrisha Rao

Distributed computing is an important field of study. Its relevance is easy to realize--the world of computing is increasingly distributed, with resources that are geographically spread, often with no central authority or assurances of performance. Tasks and services that a single person uses are increasingly likely to depend upon invocations of resources that are distributed. The safety of persons or property may also depend upon the proper functioning and coordination of diverse, uncorrelated computing elements. At present, there is a significant dichotomy in the study and practice of distributed computing. On the one hand, academics study it as a theoretical subject, a pure science almost, and derive theorems and protocols regarding distributed systems. On the other, practitioners who do not care much for theory attempt to create distributed systems that have to deliver real-world results. The two groups often do not speak the same language, and members of one often have little interest in what the other is doing. Until very recently, researchers in distributed computing have had to face other problems as well: the field is extensively researched but has little by way of tutorial or textbook resources, hence a newcomer or a practitioner wishing to learn was often obliged to weave through a maze of research papers in hopes of obtaining his end. Although distributed computing has been, and remains as, one of the areas of research where even relatively new graduate students can conduct useful research (provided they have been diligent in doing their homework in the first course or two they took), this problem has made it difficult for researchers to communicate the relevance and significance of their work to the larger community of computer scientists. It has also meant that a researcher presenting a paper on distributed computing to an audience of non-specialists is obliged to spend a good chunk of his allotted time in first explaining the very rudiments of the subject before moving on to his specialized topic. Part of the problem has been the lack of attention paid to distributed computing in traditional undergraduate computer science curricula (it continues to remain largely outside the pale of core subjects even in graduate studies), but then this in turn is also attributable to the lack of tutorial material. The present book by Attiya and Welch is thus a welcome addition to the literature on distributed computing, as it lays out important theoretical results in the field in a fashion that a newcomer (or a practitioner) can grasp with ease, and as it also makes a significant beginning in bridging the gap between theory and practice. As the title suggests, the book is divided into three major parts, dealing respectively with fundamentals, simulations, and advanced topics. These are in turn further subdivided into six, seven, and five chapters respectively. A course on distributed computing can be variably designed, depending on the instructor's priorities, using the first part and selected portions from the next two. The first part of the book covers the very basic ideas such as message-passing, mutual exclusion, shared memory, consensus, and logical time. The second part, which in the opinion of this reviewer is what makes the book most worthwhile, deals with abstractions for describing and designing systems to solve, or simulate, real problems such as broadcast and multicast. The discussion on read/write registers and the like is crucial to the field and has attracted extensive interest, but has not previously been covered outside the research literature. The last part of the book deals with some advanced questions which an interested student may refer to en route to his plunge into the current research literature. The student exercises and `Chapter Notes' given at the end of each chapter are useful instructional resources; the publisher also has solutions to selected exercises available upon request to instructors. The book has a small number of mostly self-correcting typographical errors; the author Attiya has a list of errata on her Web site.