TABLE OF CONTENTS We start this book with a short chapter on basic concepts. The idea is not to overwhelm the reader with explanations but only to provide as much information as is necessary to understand the content of the following chapters. The reader should check the literature for additional information on the individual topics (for example, see [10], [11], and [34]). We begin by first presenting some basic concepts related to distributed systems. This is followed by a description of an object model that is particularly suitable for modeling distributed applications. We then present a first overview of the structure and tasks of middleware. We conclude the chapter by presenting a simple sample application that is continued in the subsequent two chapters.
The theory behind distributed systems forms the basis for the middleware discussed in this book. This section explains some of the aspects of distributed systems that are necessary for understanding the material discussed in the chapters that follow. We can only provide an overview here of the theory behind distributed systems. The reader should refer to the literature for further information on this subject (for example, see [10] or [26]).
Characterization of a distributed system The literature presents various definitions of what a distributed system is. According to [3], a distributed system is characterized as follows:
A distributed system is an information-processing system that contains a number of independent computers that cooperate with one another over a communications network in order to achieve...
