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Über dieses Buch

This book presents a selection of subjects which the authors deem to be important for information systems engineers. The book is intended for introductory teaching. We have tried to write the book in such a way that students with only fragmented knowledge of computers are able to read the book without too many difficulties. Students who have had only an intro­ ductory course in computer programming should be able to read most of the book. We have tried to achieve simplicity without compromising on depth in our discussions of the various aspects of information systems engineering. So it is our hope that also those who have deeper knowledge in computing may find pleasure in reading parts of the book. The writing of a textbook is a major undertaking for its authors. One is quite often forced to reexamine truisms in the subject area, and must be prepared to reevaluate one's opinions and priorities as one learns more. In particular this is so in new fields, where formalisms have been scarcely used, and where consensus has not yet emerged either on what constitutes the subject area or on how practical problems within the field shall be approached. Contemporary practice in computer applications is confronted with an increasingly complex world, both in a technical sense and in the complexity of problems that are solved by computer.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract
A modern society is completely dependent on computers. They are found everywhere. They are used for supporting information processing tasks that range from the most mundane to the most complex tasks imaginable. The production and servicing of computers is one of the largest industries in the world.
Arne Sølvberg, David Chenho Kung

Chapter 2. Structured Analysis and Design

Abstract
The Structured Analysis and Design method is the currently most widespread and popular approach to information system development. It is a simple method. It is easy to understand, and it captures most of the relevant features of conventional, transaction-oriented data processing.
Arne Sølvberg, David Chenho Kung

Chapter 3. Software Design

Abstract
Data system design is the process of taking a logical model of an information system, together with objectives for that system, and producing the specification of a data processing system and its external interactions that will meet those objectives.
Arne Sølvberg, David Chenho Kung

Chapter 4. Database Design

Abstract
The overall objective of database design is to enable all users to obtain the data they require in an efficient and timely manner. This objective breaks down into two areas:
(1)
The database should be able to satisfy all of the data needs that have been specified, and it should be sufficiently flexible to meet those that will be required in the future.
 
(2)
The database must perform efficiently, i.e., allowing data to be accessed fast enough for application systems to meet their objectives while using a minimum of computer resources.
 
Arne Sølvberg, David Chenho Kung

Chapter 5. Rule Modeling

Abstract
In the analysis and design of information systems, we are frequently required to specify information system functions that evaluate complex combinations of conditions and perform appropriate actions. The specification of these functions depends on the logic of the problem that is under consideration. Since the functions are implemented by processes, the task of specifying these functions is by some authors [GANE78] called the specification of process logic. The task requires special treatment because there are a variety of problems that need to be considered. Some application problems need to perform a large number of actions, while others may perform only a few. On the other hand, there are applications that require evaluating many combinations of conditions to determine which of the actions are to be performed, while only a few combinations are possible in other applications. Therefore, we need different tools to solve different problems. Some of the most widely used tools will be studied in this chapter. These tools are commonly called structured tools, i.e., structured English, decision trees, and decision tables.
Arne Sølvberg, David Chenho Kung

Chapter 6. Information Systems Evolution: The Software Aspect

Abstract
Most information systems are in a continuous state of evolution. Contributing to this state of affairs is that systems objectives change over time, available implementation technologies change, the cost/performance ratios change for the available implementation technologies, the needs of the users of the systems change, the capabilities of the available human resources change, and so on. For computerized information systems, the consequence of system evolution is that of a pressure for software modifications, because many of the features that are being changed are usually implemented in software. Because software and persons often interact very closely, software changes frequently have associated with them modifications of the behavior of the persons who have to interact with the software. One should therefore always have the human component in mind when software changes are contemplated in an information system.
Arne Sølvberg, David Chenho Kung

Chapter 7. Managing Information Systems Development Projects

Abstract
Information systems have to be treated like other organizational resources. The systems have to be developed in an orderly manner, and they have to be maintained and kept operational just like any other company resource. Over the years the information systems resources of organizations have increased in economic importance. To use 3–6% of the turnover for information processing is quite normal in modern companies. This means that development, maintenance and operation of the information systems must be properly planned and managed.
Arne Sølvberg, David Chenho Kung

Chapter 8. Information System Support for Information System Development

Abstract
Information systems used to be built from scratch, because there were few, if any, components available to base the new systems upon. This is not the case any more. Information systems are increasingly built through the reuse, modification, integration and interfacing of commercially available software components. Programming, in the original meaning of writing commands for a computer to follow, is not as dominant an activity as it used to be only a few years ago.
Arne Sølvberg, David Chenho Kung

Chapter 9. Engineering Design Principles for Unsurveyable Systems

Abstract
The real challenge of systems engineering design is to provide operational solutions for systems that are so large and so complicated that no-one can survey every detail of the system and its behavior. This is a general problem in every engineering discipline. Engineers have learned to cope with the situation. They apply some common principles in their approach to design. These principles may be formulated differently in various branches of engineering. The first section of the chapter will explain the generally agreed approach to the engineering design process.
Arne Sølvberg, David Chenho Kung

Chapter 10. Information and Information Systems

Abstract
The purpose of an information system is to collect, store, process and distribute information. The concept of information is itself not well understood. It is in some sense a relative concept, rather than an absolute one. That is, a data object is assumed to contain information if the receiver of the data interprets it in such a way that the received data adds to the knowledge of the receiver. Even if the concepts of information, data, and knowledge are interrelated in some sense, the relationships are not fully understood. There is also, so far, no complete theory of information.
Arne Sølvberg, David Chenho Kung

Chapter 11. Three Domains of Information Systems Modeling — and the Object-Oriented Approach

Abstract
We may distinguish three domains in information systems modeling: the subject domain, the interaction domain and the implementation domain [WINO79].
Arne Sølvberg, David Chenho Kung

Chapter 12. Model Integration with Executable Specifications

Abstract
Most contemporary approaches to information systems development are based on the idea that a system is built through a succession of development phases. Separate issues are dealt with in different phases. Functional issues are central to the first phase, while issues of software and database design are treated in later phases. This is explained in some detail in previous chapters of this book.
Arne Sølvberg, David Chenho Kung

Chapter 13. An Example of Comparing Information Systems Analysis Approaches

Abstract
We shall compare two approaches to information systems analysis through an example. The example system is a one-bit window protocol for message transmission. One approach is oriented towards object descriptions. The other one is a stimulus-response approach (see Sect. 1.6).
Arne Sølvberg, David Chenho Kung

Chapter 14. Formal Modeling Approaches

Abstract
We shall round off this text with a chapter on modeling approaches which aim at a higher degree of formality than most of the methods that we have covered so far. We shall give examples of static modeling approaches and dynamic modeling approaches, and also give a short introductory discussion on temporal modeling approaches.
Arne Sølvberg, David Chenho Kung

Backmatter

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