1 / 29

Chapter 2 Information Systems Development

Chapter 2 Information Systems Development. Learning Objectives. Discuss the need for an information systems development methodology and the requirements of such a methodology. Define ISD methodology, technique and tool. IS Key Concepts.

whester
Télécharger la présentation

Chapter 2 Information Systems Development

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 2Information SystemsDevelopment

  2. Learning Objectives • Discuss the need for an information systems development methodology and the requirements of such a methodology. • Define ISD methodology, technique and tool

  3. IS Key Concepts The “system” part of “IS” represents the set of interacting components: • People • system analysts, business users, managers, … • Objects / technologies, structures • hw devices, UI, telecommunication networks, WWW, … • Procedures / tasks • business processes, ISD methodologies, business rules,… In other words, we are talking about socio-technical systems The “information” part of “IS” is the result of a processed data. In organizational development, socio-technical systems (or STS) is an approach to complex organizational work design that recognizes the interaction between people and technology in workplaces.

  4. Information System A system which assembles, stores, processes and delivers information relevant to an organisation (or to society), in such a way that the information is accessible and useful to those who wish to use it, including managers, staff, clients and citizens. An information system is a human activity (social) system which may or may not involve the use of computer systems (Buckingham et al., 1987b)

  5. Change in the IS (DeMichelis et al. 1998) The group collaboration facet is concerned with people working on a common process (e.g., handling a purchase order) or on an ad-hoc project (e.g., co-authoring a report). The organizational facet is concerned with managing work from a formal organizational perspective. This facet addresses global organizational concerns, including organizational objectives and business goals, policies, regulations, as well as resulting workflow or project plans. The systems facet accounts for systems developed through the application of information technology. Such systems generally deploy conventional technologies, such as programming languages, DBMSs, files, and workflow systems. Change-related issues for information systems arise from three areas of concern -- systems, group collaboration, and organization Source : http://www.sts.tu-harburg.de/papers/1998/DDJ+98.pdf

  6. Need for IS Development Methodology • There was a growing appreciation of that part of the development of the system that concerns analysis and design and therefore of the role of the systems analyst as well as that of the programmer. • There was a realization that as organizations were growing in size and complexity, it was desirable to move away from one-off solutions to a particular problem and towards a more integrated information system. • There was an appreciation of the desirability of an accepted methodology for the development of information systems.

  7. Information Systems Development Methodology A collection of procedures, techniques, tools, and documentation aids which will help the systems developers in their efforts to implement a new information system. A methodology will consist of phases, themselves consisting of sub-phases, which will guide the systems developers in their choice of the techniques that might be appropriate at each stage of the project and also help them plan, manage, control and evaluate information systems projects. (Avison & Fitzgerald)

  8. Continue… • ISDMs aim to make the process of developing information systems, whether manual or computerized, as straightforward and as simple as possible. • They provide a consistent set of procedures to follow, and tools and techniques to use, thus making the process of managing and developing information systems more efficient and effective. • ISDMs also represent a means for the systematic development of information systems, placing emphasis on the accurate identification of user requirements.

  9. Why not have just ONE methodology? • Differences in fundamental “philosophical views” • emphasis on human aspects, scientific vs. pragmatic approach, automation of development, … • e.g. a system that • makes the most use of computers • produces the most appropriate documentation • is the cheapest to run • is implemented earliest • the most adaptable • makes the best use of the techniques and tools available • is liked by the stakeholders is a good solution

  10. SDLC (System Development Life Cycle) SSADM (Structured Systems Analysis and Design Methodology ) STRADIS(Structured Analysis, Design and Implementation of Information Systems ) YSM (Yourdon Systems Method ) OO (Object Oriented) IE (Information Engineering) SSM (Soft System Methodology) ETHICS (Effective Technical and Human Implementation of Computer Based Systems) Multiview NIMSAD DESMET ISDM Examples

  11. Technique A set of steps and a set of rules which define how a representation of an IS is derived and handled using some conceptual structure and related notation (Smolander et al. 1990). A way of doing a particular activity in the information systems development process … and any particular methodology may recommend techniques to carry out many of these activities.

  12. Technique • By using a technique, system developers perceive, define and communicate on certain aspects of the current or desired object system. • These aspects are defined by the conceptual structure of the technique and represented by the notation.

  13. The role of methods in ISD (based on Lyytinen et al. 1989).

  14. Tools • Tools are usually automated, that is, computer tools normally software to help the development of an IS • Each technique may involve the use of one or more tools that represent some of the artefacts used in information systems development … tools are usually automated, that is, they are computer tools, normally software to help the development of an information system

  15. Significant Groupings of Tools 1. Project management tools 2. Database management systems 3. Data dictionary systems 4. Systems repositories 5. Drawing tools 6. CASE (computer aided software engineering) tools

  16. Examples of methods and tools in the phases and tasks of ISD. Source: http://www.cs.jyu.fi/~jpt/doc/thesis/ime.html

  17. Relationships Among Components of a Methodology

  18. Objectives of ISD Methodologies • To record accurately the requirements for an information system. • To provide a systematic method of development so that progress can be effectively monitored. • To provide an information system within an appropriate time limit and at an acceptable cost. • To produce a system which is well documented and easy to maintain. • To provide an indication of any changes which need to be made as early as possible in the development process. • To provide a system that is liked by those people affected by that system.

  19. Themes & Approaches The following seven themes have been identified by Avison and Fitzgerald, and provide a comprehensive grouping of current ISDMs • Systems Approach • Planning Approach • Participation • Prototyping Approach • Formal Methods • Data Analysis • Structured Approaches. Avison, D.E. and Fitzgerald, G., “Information Systems Development: Current Themes and Future Directions”, Information and Software Technology, Vol. 30, 1988, pp. 458-65.

  20. Systems Approach • Based on Bertalanffy’s general system theory (GST) • Advocates an holistic approach, which considers the system as a whole, instead of looking at the various functions, or parts, of the system in isolation. • E.g. SSM - is based on the hypothesis that the only way to develop an information system effectively is by interacting with the real problem situation, and by examining the whats” and “hows” of the problem, before any attempt is made at a solution

  21. Planning Approach • Involve senior management in the analysis and determination of the objectives and strategies of an organization, commonly referred to as strategic plans. • They ensure that all levels of management are involved in information systems planning, thus ensuring that the resultant information system fulfils its requirements. • E.g. Business information analysis and integration techniques (BIAIT). It provides a means of checking whether the objectives of the organization are being met, and is related to systems theory.

  22. Participation • Greater user involvement, together with clear job satisfaction objectives, should facilitate the successful development of an information system. • Four important value judgements: • Financial, human and technical factors in information systems development can and should be treated as compatible • Everyone affected by change in the information system can and should be considered in planning it • Employees at all levels can and should develop their own information system • the overall approach to systems development should be based on the principle of reducing uncertainty • ETHICS (Effective Technical and Human Implementation of Computer-based Systems), which is built around the principles.

  23. Prototyping Approach • High levels of user involvement, attempts to present the user with an early view of the proposed system. • Prototyping is good for use in dynamic contexts, and it could be used to develop one-off, very specialized systems. • The use of prototyping would allow users to try out the prototype in its different evolutions, suggesting ways in which it could be improved, or features that would be useful. • A prototyping methodology consists of the following seven phases: (1) determine feasibility study; (2) study present system; (3) define prototype; (4) build prototype; (5) exercise prototype (which consists of programming, testing, acceptance testing and user training); (6) conversion; (7) installation of the final information system.

  24. Formal Methods • Mathematical notation is used to describe the properties which an information system must have, without unduly constraining the way in which these properties are achieved. • Thus, mathematical expressions are used to explain what the system will do (i.e. the logical view), without actually saying how this will be done (i.e. the physical view). • E.g. Vienna Development Method (VDM) and “Z” Method.

  25. Data Analysis • Emphasis on a complete and thorough analysis of the data and their relationships. • It concentrates on understanding and documenting the data in a system, rather than on the processes involved. • Data represent the “fundamental building blocks of systems”. • Data analysis is used to build a data model of the information system that is independent of implementation. • Data analysis can be used to develop any type of system, whether computerized or manual, and is particularly suited to bridging the gap between an old manual system and the new computerized system which replaces it.

  26. Structured Approaches • Based on functional decomposition – that is, the breaking down of complex entities into manageable units in a disciplined manner. • Emphasis is placed on the systematic procedures of analysis and design, which are organized within a framework of steps and stages • E.g. YSM and SSADM

  27. End of Chapter 2 Thank You for Your Attention

More Related