Book Image

The Complete Edition - Software Engineering for Real-Time Systems

By : Jim Cooling
Book Image

The Complete Edition - Software Engineering for Real-Time Systems

By: Jim Cooling

Overview of this book

From air traffic control systems to network multimedia systems, real-time systems are everywhere. The correctness of the real-time system depends on the physical instant and the logical results of the computations. This book provides an elaborate introduction to software engineering for real-time systems, including a range of activities and methods required to produce a great real-time system. The book kicks off by describing real-time systems, their applications, and their impact on software design. You will learn the concepts of software and program design, as well as the different types of programming, software errors, and software life cycles, and how a multitasking structure benefits a system design. Moving ahead, you will learn why diagrams and diagramming plays a critical role in the software development process. You will practice documenting code-related work using Unified Modeling Language (UML), and analyze and test source code in both host and target systems to understand why performance is a key design-driver in applications. Next, you will develop a design strategy to overcome critical and fault-tolerant systems, and learn the importance of documentation in system design. By the end of this book, you will have sound knowledge and skills for developing real-time embedded systems.
Table of Contents (16 chapters)
Preface
15
Glossary of terms

7.3 UML Diagrams for Object-Oriented Designs

7.3.1 Use Case Diagrams

A use case model, Figure 7.20, consists of actors, use cases, and use case descriptions:

Figure 7.20: The components of the use case model

Its purpose, in simple terms, is to show why systems are used and who uses them.

Each system has its own model, with actors depicting users (more correctly, roles performed by users). The reasons why these actors are using the system are shown as a set of use cases within the system boundary. Two simple examples are given in Figure 7.21. Each system is drawn as a rectangular box, with the relevant use cases shown as ellipses inside them (the box, representing the system boundary, is optional). Outside the system, the boundary is the actors, connected via lines to (associated with) the use cases. In (a), both the navigator actor and the pilot actor interact with the NAV/WAS system in the same way; they use it to find out what the navigation waypoints...