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1998 | Buch | 3. Auflage

Information Systems Development

An Introduction to Information Systems Engineering

verfasst von: Paul Beynon-Davies

Verlag: Macmillan Education UK

Buchreihe : Computer Science Series

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SUCHEN

Inhaltsverzeichnis

Frontmatter

Context

Frontmatter
1. Information

The concept of information and its exploitation in information systems has been somewhat taken for granted in the contemporary practice of development. Information has been treated in many respects as a mystical fluid that emanates as if by magic from the development of computerised information systems.

Paul Beynon-Davies
2. Information Systems

The term information system is used in a number of different contexts in the literature. This chapter attempts to build a workable definition of the term and in the process introduces a number of important distinctions which impinge on the material in further chapters.

Paul Beynon-Davies
3. Information Systems and Organisations

Information systems are used in the context of organisations. It has become very much of a truism to state that in modern Western economies the success of organisations is frequently very much dependent on the success of its information systems. In this chapter we discuss a number of models for organisations and how the concept of an information system and the development of such information systems fits within the framework of each model.

Paul Beynon-Davies
4. Information Society and Economy

In the previous chapter we discussed how the shape of an organisation is affected by its environment. In the normal sense of the term used within the Information Systems area, environment means the competitive marketplace. In this chapter we broaden the meaning of this term to include the way in which information and information systems are affecting societies and economies.

Paul Beynon-Davies
5. Information Technology

In chapter 2 we described three levels at which information systems may be addressed. In most modern-day organisations, the lowest level of information system, that of a technical information system or an information technology system, has become increasingly important. In this chapter we discuss at a reasonably high level the component parts of such systems.

Paul Beynon-Davies
6. Information Systems Services Function

Most medium to large scale organisations have people specifically employed in IS work. In this chapter we consider a number of important issues in relation to how this function is or should be organised. The name of such a function will vary amongst organisations. In some organisations it may be called the IT or IS department, perhaps even the DP (data processing) department. In this chapter we refer to it generically as the IS services function, to emphasise that in most organisations IS is a critical supporting or strategic service supplied to the organisation.

Paul Beynon-Davies
7. Information Systems Engineering

In chapter 1 and chapter 2 we introduced the context for information systems development in terms of preliminary definitions for the terms information and information system. In chapter 3 we discussed some of the consequences of information and information systems for organisations and in chapter 6 we described some of the features of the information service within organisations.

Paul Beynon-Davies

Tools

Frontmatter
8. Structured Programming Languages

Programming languages are used to describe algorithms, i.e. sequences of steps that lead to the solution of problems. Programming languages are broadly classified into two groups: low-level languages and high-level languages. Low-level languages are close to machine languages. They demonstrate a strong correspondence between the operations implemented by the language and the operations implemented by the underlying hardware. High-level languages in contrast are closer to human languages. Each statement in a high-level language will be equivalent to many statements of a low-level language. The key advantage offered by high-level languages is therefore abstraction. As the level of abstraction increases the programmer needs to be less and less concerned about the hardware on which a program runs and more and more concerned with the problems of the application. Hence, the trend has been to build more and more abstraction into programming languages.

Paul Beynon-Davies
9. Object-Oriented Programming Languages

The fundamental difference between conventional and object-oriented programming (OOP) relates to the way each approach treats data and process. In conventional programming (chapter 8) data and process are separate things. To create an information system we define our data structures and then we define routines to operate upon them.

Paul Beynon-Davies
10. Database Systems

When organisations first began to use the computer they naturally adopted a piecemeal approach to information systems development. One manual system at a time was analysed, redesigned and transferred onto the computer with little thought to its position within the organisation as a whole. This piecemeal approach was necessitated by the difficulties experienced in using a new and more powerful organisational tool.

Paul Beynon-Davies
11. Fourth Generation Environments

As with many terms in computing the concept of fourth generation languages (4GLs) and environments is an extremely hazy one. One way to distinguish between third generation and fourth generation tools is to express the ideal of a non-procedural development environment. It must be remembered however that few if any contemporary products satisfy this ideal.

Paul Beynon-Davies
12. Computer Aided Information Systems Engineering (CAISE)

In this chapter we shall discuss the growing number of automated tools for information systems development. Many people place such tools within the context of CASE — Computer Aided Software Engineering. The author prefers the term CAISE — Computer Aided Information Systems Engineering — in that CASE may be regarded as a subset of CAISE. Many CAISE tools are involved in the direct construction of software and are hence logically software engineering tools. Many others are not directly involved in the production of software but in other artefacts associated with the IS development process. Most database design tools, for example, have as their remit the production of structures for storing and manipulating data. Also, project management tools enable the production of documents associated with the management of IS projects rather than any application-specific detail.

Paul Beynon-Davies
13. Multimedia and Hypermedia Systems

Hypermedia is the approach to building information systems made up of nodes of various media (such as text, audio data, video data, etc.) connected together by a collection of associative links. A subset of this discipline known as hypertext concentrates on the construction of loosely connected textual systems. The term multimedia is frequently used as a synonym for hypermedia, although strictly multimedia refers to any system that handles multiple media. Hence, multimedia may be seen as superset of hypermedia.

Paul Beynon-Davies
14. Knowledge Based Systems

Knowledge based systems (KBS), sometimes referred to as intelligent knowledge based systems (IKBS), were much discussed in the literature during the 1980s. In the 1990s they have become an accepted tool in the information systems developer’s toolkit. This chapter attempts to explain exactly what is meant by a knowledge based system and makes some suggestions as to the place of knowledge based systems within information systems development.

Paul Beynon-Davies

Techniques

Frontmatter

Data Analysis

15. Normalisation

In his seminal paper on the relational data model, E.F. Codd formulated a number of design principles for a relational database (Codd, 1970). These principles were expressed in terms of three normal forms. The process of transforming a database design through these three normal forms is known as normalisation. By the mid-1970s third normal form was shown to have certain inadequacies and a stronger normal form, known as Boyce-Codd normal form was introduced (Codd, 1974). Subsequently, Fagin introduced fourth normal form and fifth normal form (Fagin 1977, 1979).

Paul Beynon-Davies
16. Entity-Relationship Diagramming

Database design is fundamentally a task in data modelling. A data model is an architecture for data (chapter 10). Brodie has made a distinction between three generations of data model (Brodie, 1984): 1.Primitive Data Models. In this approach objects are represented by record-structures grouped in file-structures. The main operations available are read and write operations over records.2.Classic Data Models. These are the hierarchical, network and relational data models. The hierarchical data model is an extension of the primitive data model discussed above. The network is an extension of the hierarchical approach. The relational data model is a fundamental departure from the hierarchical and network approaches.3.Semantic Data Models. The main problem with classic data models like the relational data model is that they maintain a fundamental record-orientation. In other words, the meaning of the information in the database, its semantics, is not readily apparent from the database itself. The user of databases using the classic approach must consciously apply semantic information. For this reason, a number of so-called semantic data models have been proposed (King and McLeod, 1985). Semantic data models (SDMs) attempt to provide a more expressive means of representing the meaning of information than is available in the classic models.

Paul Beynon-Davies

Process Analysis

17. Data Flow Diagramming

A data flow diagram (DFD) is a representation of a system or subsystem in terms of how data moves through the system.

Paul Beynon-Davies
18. Process Descriptions

According to the structured development tradition, information systems are generally described in terms of three major components: data flows, data structures and processes. Data flows are the subject of the chapters on DFDs (chapter 17) and data dictionaries (chapter 19). Data structures have been discussed using the techniques of normalisation (chapter 15) and E-R diagramming (chapter 16). The third component, processes, are the subject of the current chapter.

Paul Beynon-Davies
19. Data Dictionaries

A data dictionary is a means for recording the metadata of some organisation (Navathe and Kerschberg, 1986). That is, data about data. Data dictionaries have been used in three ways within information systems development: 1.Conceptual data dictionaries record meta-data/process at a very high level of abstraction.2.Logical data dictionaries are used to record process and data requirements independently of how these requirements are to be met. Logical meta-data is however at a slightly lower level of abstraction than conceptual meta-data.3.Physical data dictionaries are used to record design decisions. In terms of data, physical dictionaries store details relating to actual database or file structures. The system tables at the heart of a relational DBMS are a physical data dictionary. In terms of process, physical dictionaries may store details of programs and program libraries.

Paul Beynon-Davies
20. Entity Life Histories

The entity life history (ELH) technique was originally designed to extend the available database design techniques such as E-R diagramming (chapter 16) and normalisation (chapter 15) (Robinson, 1979). Such data analysis techniques concentrate almost exclusively on a static view of the information system being modelled. ELHs, in contrast, were developed as a technique for the explicit modelling of system dynamics (Rosenquist, 1982). In this sense, the ELH may be seen as a competitor to the DFD (chapter 17) and associated process specification techniques (chapter 18). However, the ELH is more closely linked to the logical modelling ideas underlying data analysis.

Paul Beynon-Davies

Other Techniques

21. Structured Program Design

In previous chapters we have concentrated on a range of techniques applicable to the analysis and design of information systems. In this chapter we begin to concentrate on implementation. We discuss a number of techniques applicable to the process of program design.

Paul Beynon-Davies
22. Object-Oriented Analysis and Design

Object-Oriented (OO) is definitely having an impact upon systems analysis, systems design, programming (chapter 8), and most recently database systems (chapter 10). The main aim of this chapter is to portray how conceptual modelling as applied to database systems can move relatively painlessly into the domain of OO (Beynon-Davies, 1992). We will discuss how OO analysis, an approach primarily directed at the building of applications in procedural or object-oriented languages, is equally relevant to the development of database systems.

Paul Beynon-Davies
23. User Interface Design

What is the user interface? In one sense we might define the user interface as everything concerning the human side of information systems, an area referred to as human factors or human-computer interaction (HCI) (Preece et al., 1995). Hence, all those topics related to the social dimension of information systems development might be seen as having a bearing on the user interface.

Paul Beynon-Davies
24. Prototyping

In chapter 7 we discussed the waterfall model of information systems development. This model is generally held to be an excellent vehicle for the production of large-scale information systems from well-defined environments. A well-defined environment is usually one in which there is either some manual system waiting to be computerised, or there is an existing computer system that has to be overhauled and perhaps extended.

Paul Beynon-Davies

Methods

Frontmatter

Business Analysis Methods

25. Business Process Re-engineering

In the early 1990s a new term started to appear amongst numerous IS publications — business process re-engineering (BPR). This was initially popularised by a number of influential articles published by Michael Hammer leading to a book of this title written by Hammer and Champy (1993). They define Business Process Re-engineering as: ‘The fundamental rethinking and radical redesign of business processes to achieve dramatic improvements in critical, contemporary measures of performance, such as cost, quality, service and speed.’ At about the same time another influential, if more conservative book by Davenport and Short (1990), defined BPR as: The analysis and design of work flows and processes within and between organisations. ‘

Paul Beynon-Davies
26. Soft Systems Methodology

As we have mentioned, there is no one agreed approach to conducting business analysis. Therefore, most of the discussion in this chapter draws upon the work of Peter Checkland and his associates at the University of Lancaster. Over the last couple of decades Checkland has been developing the framework of an approach known as soft systems methodology (SSM) (Checkland, 1987). This method has been adapted to the needs of government departments and renamed Business Analysis Technique (CCTA, 1990). Avison and Wood-Harper (1990) have demonstrated also how the techniques of soft systems methodology can lead into conventional ‘hard’ systems analysis.

Paul Beynon-Davies

Development Methods

27. Structured Methods

Part 3 was devoted to describing a number of techniques popular in contemporary systems analysis and design. Presenting the techniques as a relatively discrete set of components has hopefully emphasised that the individual systems developer can frequently select appropriate techniques as and when they are needed during the life-cycle of a particular project. This means that because of the large number of choices available, a large number of possible development approaches can be created.

Paul Beynon-Davies
28. Participatory Design

In recent years there has been something of a renaissance of interest in the idea of Participatory Design (PD) of information systems (IS). Participatory Design might be defined as any attempt to include significant stakeholders, particularly end-users in the process of developing an information system. Lytinnen and Hirschheim (1987) define stakeholders as being ‘all those claimants inside and outside the organisation who have a vested interest in the problem and its solution’. Friedman (1989) believes that this focus on user relations constitutes a distinct phase in the history of computing equivalent in stature to two previous phases focused on hardware and software constraints.

Paul Beynon-Davies
29. Rapid Applications Development

Rapid Applications Development (RAD) seems to be a term that is currently used in association with a whole range of tools, techniques, methods, and indeed even information systems management styles. In this chapter we describe some of the key features of RAD approaches.

Paul Beynon-Davies
30. Object-Oriented Methods

Graham (1994) discusses the various approaches to object-oriented analysis and design in terms of three dimensions: process, data, and dynamics or control. Methods fall into two basic types: ternary and unary. Ternary methods (such as Rumbaugh’s OMT and Martin and Odell’s Ptech) apply different techniques (frequently adaptations from the structured approaches) to each of these dimensions of information systems modelling. Unary methods (such as Coad and Yourdon and Wirfs-Brock) attempt to incorporate all three dimensions in one consistent O-O approach. Graham defines his own method, called SOMA, which he describes as a hybrid approach in that it attempts to utilise the strengths of various approaches.

Paul Beynon-Davies

Management

Frontmatter
31. Project Management

In this chapter we address the issues of managing information systems projects. We define a project here as being any concerted effort to develop an information system.

Paul Beynon-Davies
32. Information Systems Management

Planning is the process of determining what to do over a given time-period. Managing is the process of executing, evaluating and adapting plans in the face of contingencies. The issue of management and how it relates to IS development is a large one. In this chapter we limit ourselves to discussing the following issues: the perceived role of the IS services function, the importance of IS/IT to the organisation and the role of risk in managing the applications development portfolio.

Paul Beynon-Davies
33. Information Systems Planning

Information systems planning is the process of deciding upon the optimal information, information systems, and information technology architecture for some organisation.

Paul Beynon-Davies
34. Information Systems Evaluation

In recent years a number of questions have been frequently voiced by general management within organisations in relation to information systems and information technology: 1.Do we know how much is currently spent on IS?2.What value results from this spending?3.How should IS alternatives be justified/ prioritised/ financed?4.Why do IS budgets continue to rise while IT unit costs continue to fall?5.How can we regain our belief in IS returns?

Paul Beynon-Davies
35. Information Systems Outsourcing

Outsourcing might be defined as the use of external agents to perform one or more organisational activities. In the last decade or so there has been a trend, particularly among large-scale companies, to hand over either the whole or part of the IS function to external agents.

Paul Beynon-Davies
36. Quality Assurance

Quality assurance or software quality assurance has been defined as a planned and systematic pattern of all the actions necessary to provide adequate confidence that software conforms to established technical requirements (Chow, 1985). The key ideas of quality assurance are: 1.Comprehensiveness. Quality assurance is not restricted to the function of a software quality group or phase. It includes all the necessary activities that contribute to the quality of software throughout the entire life cycle of a project.2.Planning. The emphasis is on a systematic plan to achieve the objectives of software quality. The quality of a piece of software is not left to the efforts of individuals.3.Relativity. The notion of quality is relative to some requirements. There is no absolute sense of quality. The purpose of quality assurance is not to guarantee 100% reliability or zero defect software. It is rather to increase confidence that every reasonable effort has been made to ensure the quality of the end product. Quality therefore equals conformance to requirements, not excellence.4.Cost. When purchasing any product, the level of quality of a product is usually reflected in its price. Hence, software quality involves increased cost. Product quality is therefore wholly a matter of customer choice. It is essential at the requirements analysis stage for the analyst to identify appropriate customer quality needs.

Paul Beynon-Davies

The Discipline of Information Systems Development

Frontmatter
37. Information Systems Failure

Information Systems (IS) failure is a topic which has become extremely newsworthy both in the general and the computing press in recent years. As a consequence, there is some evidence of an increasing concern amongst organisations in the UK and elsewhere with the large amounts of money which appears to have been devoted to software projects with little apparent organisational benefit. Available literature suggests that failure is a ubiquitous feature of both the UK and International experience of IS engineering (Coopers and Lybrand, 1996).

Paul Beynon-Davies
38. Information Systems and Their Interaction with Organisations

In this chapter we shall use what Silver, Markus and Beath (1995) have referred to as an IT interaction model as a means of discussing the key focus of information systems as a discipline and, in particular, the place of IS development activities within organisations. We prefer to call it an IS/IT interaction model because we wish to include both IS and IT in our discussion. This model is useful in discussing the place of information systems in organisations. It is referred to as an interaction model because it is founded on the premise that the consequences of IS in organisations follow from the interaction of the technology with the organisation and its environment. The effects of an information system for an organisation emerge over time as the result of the interaction of the IS with its organisational context. Understanding the nature of this interaction is therefore central to obtaining the benefits of IT as well as avoiding the hazards that IT can hold for organisations (see figure 38.1).

Paul Beynon-Davies
39. The Professionalisation of IS Work

The ubiquity of modern information systems has caused a debate within the community involved in their development about the status of their work. Societies such as the British Computer Society (BCS) and the Institute of Electronic Engineers (IEE) have attempted to cast information systems work as a true profession in much the same guise as lawyers, accountants, architects and the medical profession (Beynon-Davies, 1993).

Paul Beynon-Davies
40. The Development of the Discipline of Information Systems

In this, the final chapter, we discuss the development of the discipline of information systems. First, we return to the issue of what constitutes the discipline. Second, we consider the place of information systems development within the discipline of information systems. Third, we discuss areas of much-needed research in information systems development. Fourth, we describe some possible strategies for ISD research.

Paul Beynon-Davies
Backmatter
Metadaten
Titel
Information Systems Development
verfasst von
Paul Beynon-Davies
Copyright-Jahr
1998
Verlag
Macmillan Education UK
Electronic ISBN
978-1-349-14931-5
Print ISBN
978-0-333-74481-9
DOI
https://doi.org/10.1007/978-1-349-14931-5