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Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
Acca 11(information systemsdevelopmentprocess)
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Acca 11(information systemsdevelopmentprocess)

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System development lifecycle …

System development lifecycle
The Waterfall Model
The Spiral Model
Systems development methodologies
Software support for the systems development process
User involvement

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  • 1. 1 Information Systems Development Process Lecture 11 Abdisalam Issa-Salwe Faculty of Professional Studies Thames Valley University
  • 2. Abdisalam Issa-Salwe, Thames Valley University 2 Topic list  System development lifecycle  The Waterfall Model  The Spiral Model  Systems development methodologies  Software support for the systems development process  User involvement
  • 3. Abdisalam Issa-Salwe, Thames Valley University 3 System development cycle  In early days of computing, systems were developed in fairly haphazard way resulting in poorly designed systems which were too expensive and were not suited to the user’s needs  In the 1960s, the National Computing Centre developed a more disciplined approach to systems development which was applicable almost everywhere
  • 4. Abdisalam Issa-Salwe, Thames Valley University 4 System development cycle (cont…) This approach was called the Systems Development Lifecycle and contained the following stages:  Feasibility Study  Systems Investigation  Systems Analysis  Systems Design  Implementation  Review and Maintenance
  • 5. Abdisalam Issa-Salwe, Thames Valley University 5 System development cycle (cont…)  System development life-cycle was developed to add discipline to many organisations’ approach to systems development.  Systems development lifecycle is the process of conceiving, designing and implementing an information system.
  • 6. Abdisalam Issa-Salwe, Thames Valley University 6 System development cycle (cont…)  The Systems Development Life Cycle (SDLC) is a framework for describing the phases involved in developing and maintaining information systems  Typical SDLC phases include planning, analysis, design, implementation, and support
  • 7. Abdisalam Issa-Salwe, Thames Valley University 7 Systems View  Systems approach emerged in 1950s  more analytical approach to management & problem solving  Three parts:  Systems philosophy: View things as systems, interacting components working within an environment to fulfill some purpose  Systems analysis: problem-solving approach  Systems management: Address business, technological & organizational issues before making changes to systems
  • 8. Abdisalam Issa-Salwe, Thames Valley University 8 Drawbacks of the systems development  Insufficient emphasis on information needs  Sequential, inflexible approach  Poor documentation  Dissatisfied users  Users’ requirements poorly defined
  • 9. Abdisalam Issa-Salwe, Thames Valley University 9 Drawbacks of the systems development (cont…)  As information systems grow in size and complexity, these problems may only get worse.  The best way to start approaching these problems is by studying them in more detail.  Legacy Systems  Increasing Systems Complexity  Organisational Issues
  • 10. Abdisalam Issa-Salwe, Thames Valley University 10  The IS function has a poor reputation.  Despite huge investments in information technology:  Systems development often takes more time and resources than planned  Information systems do not provide the information needed or in the needed form  Information systems break down too often Drawbacks of the systems development (cont…)
  • 11. Abdisalam Issa-Salwe, Thames Valley University 11 Drawbacks of the systems development (cont…)  Birrell and Ould [Birrell and Ould, 1985], describe the "b-Model“:  The b-Model recognises that the maintenance phase of the software life- cycle is seldom just fixing errors.  If a software product exists for any period of time, "maintenance" almost always involves enhancements.  After a while, the "maintenance phase" of a software product looks very much like the "development phase."
  • 12. Abdisalam Issa-Salwe, Thames Valley University 12 SSADM  SSADM (Structured Systems Analysis and Design) Originally designed for the UK Civil Service. Data driven – concentration on the data rather than processes. Highly structured with rules, guidelines and standards Documentation is crucial to all aspects of the system project development
  • 13. Abdisalam Issa-Salwe, Thames Valley University 13 SSADM states  Stage 0 – Feasibility Study  Stage 1 – Investigation of Current Environment  Stage 2 - Business Systems Options  Stage 3 – Definitions of requirements  Stage 4 – Technical Systems Options  Stage 5 – Logical Design  Stage 6 – Physical Design
  • 14. Abdisalam Issa-Salwe, Thames Valley University 14 Computer-Aided Software Engineering Tools (CASE)  Software tools providing automated support for systems development  Project dictionary/workbook: system description and specifications  Diagramming tools  Example products: Oracle Designer, Rational Rose
  • 15. Abdisalam Issa-Salwe, Thames Valley University 15 CASE Tools (cont…)  Select - Select  Visio 2000 – Microsoft  Visible Analyst - Visible Systems  ER/Studio - Embarcadero  ERWin - Computer Associates  Oracle Designer - Oracle  Power Designer - Sybase
  • 16. Abdisalam Issa-Salwe, Thames Valley University 16 CASE Features  Diagrams  Documentation  Data Dictionary  Team Coordination  Prototyping  Code Generation  Reverse Engineering
  • 17. Abdisalam Issa-Salwe, Thames Valley University 17 CASE Types  Full development - integrated  iCASE  Analysis & Design  upper CASE  Implementation & Maintenance  lower CASE
  • 18. Abdisalam Issa-Salwe, Thames Valley University 18 CASE Repository  Data dictionary - data element definitions and descriptions  Ensures consistency  Repository is much more  Database with linkages for all system development products and activities  Integration  Even across different CASE tools
  • 19. Abdisalam Issa-Salwe, Thames Valley University 19 System Development Methodologies  System Development Methodologies - Refer to tools and techniques used to complete tasks of various phases. We may use structured design technique to design computer programs; the technique would be a methodology where as system design is a phase of the life cycle
  • 20. Abdisalam Issa-Salwe, Thames Valley University 20 System Development Methodologies (cont…)  A system development methodology is a guidelines to follow for completing every activity in the SDLC, including specific models, tools and techniques.  Some methodologies are very formal, and contain direct instruction. Everything is defined, including the view of documentation and content of reports.  Other methodologies are much more informal – just general description of what should be done.
  • 21. Abdisalam Issa-Salwe, Thames Valley University 21 System Development Methodologies (cont…)  Different types of system development methodologies are used in designing information system.  Depending upon the actual requirement of the system, different approaches for data processing are adopted. However, some system groups recommends the Centralised data processing system while others may go in for distributed data processing system.
  • 22. Abdisalam Issa-Salwe, Thames Valley University 22 Model  A model is a representation of some aspect of the real world. A model may be:  physical (like a model of an airplane) or  abstract (e.g. in form of mathematical notation or in graphical form).  Most models, used in system development, are graphical (diagrams and charts). They include representations of inputs, outputs, processes, data, objects, object interactions, locations, networks, devices, or highlighting the tasks for the project
  • 23. Abdisalam Issa-Salwe, Thames Valley University 23 Tools  A tool is a software support that helps create models or other components required in the project. A list of tool types includes:  Project management application  Drawing/graphics application  Word processor/text editor  Computer-aided system engineering (CASE) tools  Integrated development environment (IDE)  Database management application  Reverse-engineering tool  Code generator tool
  • 24. Abdisalam Issa-Salwe, Thames Valley University 24 Technique  A technique is a collection of guidelines that help the analyst complete a system development activity or task.  It might be step-by-step instructions or more general advices.
  • 25. Abdisalam Issa-Salwe, Thames Valley University 25 Technique (cont…)  Strategic planning techniques  Project management techniques  User interviewing techniques  Data-modeling techniques  Relational database design techniques  Structured analysis technique  Structured programming technique  Software-testing techniques (e.g. usability testing)  Object-oriented analysis and design techniques
  • 26. Abdisalam Issa-Salwe, Thames Valley University 26
  • 27. Abdisalam Issa-Salwe, Thames Valley University 27 Computer Generation  First generation: machine language  Second generation: assembly language  Third generation: high-level programming languages, such as C, C+ +, and Java.  Fourth Generation  fifth generation: languages used for artificial intelligence and neural networks.
  • 28. Abdisalam Issa-Salwe, Thames Valley University 28
  • 29. Abdisalam Issa-Salwe, Thames Valley University 29 Machine language (1GLs) The lowest-level programming language (except for computers that utilise programmable microcode)  Machine languages are the only languages understood by computers.  While easily understood by computers, machine languages are almost impossible for humans to use because they consist entirely of numbers
  • 30. Abdisalam Issa-Salwe, Thames Valley University 30 Assembly language (2GLs)  A programming language that is once removed from a computer's machine language.  Machine languages consist entirely of numbers and are almost impossible for humans to read and write.  An assembly language contains the same instructions as a machine language, but the instructions and variables have names instead of being just numbers.
  • 31. Abdisalam Issa-Salwe, Thames Valley University 31 Fourth-Generation Languages (4GLs)  Often abbreviated 4GL, fourth- generation languages are programming languages closer to human languages than typical high- level programming languages. Most 4GLs are used to access databases. For example, a typical 4GL command is:  FIND ALL RECORDS WHERE NAME IS "SMITH"
  • 32. Abdisalam Issa-Salwe, Thames Valley University 32 5GLs  Fifth generation: languages used for artificial intelligence and neural networks.  the branch of computer science concerned with machine behave like humans. Example:  Game playing  Neutral network  Robotics,  Etc.
  • 33. Abdisalam Issa-Salwe, Thames Valley University 33 User involvement • User involvement focuses the needs and wishes of users, i.e. crucial information that must be incorporated into the design process to ensure user acceptance. •  To begins by classifying the users of a product into several distinct user groups. • Groups then examined using methods such as in-person interviews, group interviews.
  • 34. Abdisalam Issa-Salwe, Thames Valley University 34 User involvement   Walkthroughs: Walkthroughs investigate how a product is used in its actual usage environment and what are expectations and wishes of users concerning the product. In an unstructured walkthrough the user is allowed to freely demonstrate her way of using the product, while in a structured walkthrough the user is asked to perform specific tasks.

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