Real-time system designers, those who write software with time constraints, will be happy to read this book, which demonstrates how to use unified modeling language (UML) to model real systems.

The value of this book is its accessible presentation of UML and real time, extracting the main concepts. A great feature is that each chapter has dozens of exercises, to provoke active reading. The success of this book is also measured by the fact that it has reached a third edition, which covers version 2.0 of UML.

The book presents examples using two products created by I-Logix (the company where the author is the chief scientist): a process called ROPES (rapid object-oriented process for embedded systems), and a modeling tool called Rhapsody. Many illustrations demonstrate the implementation of the concepts in Rhapsody. Sometimes, it is not clear whether a section describes a standard concept, or if it is only a ROPES/Rhapsody-specific feature.

The first chapter defines real-time systems as those where time, robustness, and performance are critical. This makes the design and testing of real-time systems much more difficult than the design and testing of regular software applications. A big part of this chapter addresses the scheduling of real-time systems.

UML’s general features are presented in chapter 2 (structural issues, like classes and relations) and chapter 3 (dynamic aspects, like state diagrams and sequence diagrams). While UML is often considered complex and hard to grasp, these two chapters explain the essential features. Many diagrams are presented, either as drawings or as screen shots from the Rhapsody tool.

Chapter 4 moves to the real-time world, presenting the UML profile for schedulability, performance, and time (SPT), a standard defined by the Object Management Group (OMG). A UML profile is an extension of UML to be used in a specific domain. This real-time UML profile is presented in detail. At the end of the chapter, the real-time common object request broker architecture (CORBA) subprofile is also briefly presented.

The next three chapters describe UML-based analysis of requirements, the object domain, and object behavior. Though very accurate, the presentation is done in plain language. Most of the presentation is UML-generic, though some parts are real-time specific. There are several pictures of UML diagrams, presenting various examples of analysis.

Chapters 8 through 10 address the three levels of system design: architectural (packages, tasks, and processors), mechanical (classes, objects, and design patterns), and detailed (data structures and algorithms). These chapters include both UML diagrams and code fragments in C++ and Java. I particularly liked the typographic presentation of those chapters, namely their use of headings, bullets, and fonts. The last chapter describes the US Department of Defense’s architectural framework, called C4ISR. A very useful appendix describes the UML notation summary.

I recommend this as a great book for learning UML in detail, understanding real-time systems, and learning how to model them with UML.