Both the theory and practice of real-time systems have significantly evolved to the extent that 15 years in the development of a discipline looks like an era. This situation is reflected in this revised edition (the first edition was published in 1997 [1]). The book includes new chapters on simplicity, energy awareness, and the Internet, and, more importantly, some of the original chapters have been substantially revised.

The book was designed to be a textbook. Its audience includes graduate and senior-level undergraduate students in real-time systems courses, as well as practitioners. To use it efficiently, a background is needed in computer science or computer engineering. It is even organized into 14 chapters to support its use in a 14-week semester.

The first chapter introduces the main concepts of real-time systems--that is, their classification as well as a discussion of functional, temporal, and dependability requirements. The next chapter, “Simplicity,” which is in fact on complexity, is surprising in that it does not include enough technical material--something I would like to be able to offer to students. It may be good for initiating discussion in a graduate seminar, but its content does not justify a separate chapter; instead, it would nicely fit into the introductory chapter, as a section among those currently included on requirements. At any rate, in the current format it does not appear to contribute much to the book’s value.

The next three chapters--“Global Time,” “Real-Time Model,” and “Temporal Relations”--form the fundamental part of the book. Kopetz presents the nature of time when building real-time systems; the fundamental concepts related to the progression of time, the intricacies of measuring time, and other important parameters; and the concept of determinism, which is so crucial in real-time system design. The next two chapters, “Dependability” and “Real-Time Communication,” continue an interesting presentation of what used to be the author’s strongest research contribution: various aspects of fault-tolerant principles. A solid explanation of fault-tolerant concepts in a text on real-time systems is not that common, and I consider this part of the book just as valuable as the aforementioned section on real-time system models.

The next major part of the book (chapters 9 through 12) is also interesting; it covers various development and design aspects of real-time systems, with separate chapters on real-time operating systems, real-time scheduling, system design, and validation. Understandably, these chapters are much less detailed than books that specifically focus on real-time system design (for example, Bo Sandén’s book [2]), since this wasn’t the author’s objective. Nevertheless, the fact that it lacks some of the material is a bit annoying. For example, in the chapter on real-time operating systems, there does not seem to be any mention of the POSIX standard (real-time application programming interface (API)), an essential component of every commercial real-time kernel.

I took a closer look at some of the new chapters. Reading the chapter on power awareness (8), I came to the conclusion that it could be a part of a more comprehensive section on the hardware level of real-time systems, to include issues related to bus architectures in particular. This sort of material is missing from the current edition, and it would be good to include it later on, if the book is to keep its promise of presenting the material at an architectural level. Chapter 13, “Internet of Things,” is, in my opinion, not necessary; it contains very little technical information. Maybe renaming it “Conclusion” or “Final Remarks” would cause less confusion for the reader. The book ends with chapter 14, “The Time-Triggered Architecture.”

Overall, this is a very good book. Given the fact that it is extremely difficult to keep up with the pace of developments in the real-time systems field, Kopetz manages to present the most important principles for understanding and designing such systems, and even spices it up with some personal views on the subject. Personally, I would like to see a more extensive treatment of the author’s strongest topic, time-triggered systems, at the expense of some of the less critical topics mentioned above.