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Systems Development: A Survey

Chapter 11. Systems Development: A Survey. Overview. Systems development is the process of modifying or replacing a portion or all of an information system. This process requires a substantial commitment of time and resources and is an ongoing activity in many organizations.

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Systems Development: A Survey

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  1. Chapter 11 Systems Development:A Survey

  2. Overview • Systems development is the process of modifying or replacing a portion or all of an information system. • This process requires a substantial commitment of time and resources and is an ongoing activity in many organizations.

  3. Organizational Context of Systems Development • In information systems terminology, a user or end user is an organizational function other than the information system function that requires computer data processing. • The information system function is separate from user functions.

  4. Organizational Context of Systems Development Users Information Systems System Requirements Systems Analysis Systems Design Operations System Output

  5. Systems Analysis • Systems analysis is responsible for the development of the general design of system applications. • Systems analysis works with users to define their specific information requirements. • These requirements are then communicated to the systems design function.

  6. Systems Analysis • There are four general phases in systems analysis: • Survey the existing system. • Identify the information needs of users. • Identify the system requirements that are necessary to satisfy the information needs of users. • Prepare a systems analysis report.

  7. Systems Design • What is systems design? • There are three general phases in systems design. • What are these three phases? • Evaluate alternative designs for the proposed system. • Prepare detailed design specifications. • Prepare the systems design report.

  8. Operations • The operations subfunction of information systems actually operates the computer equipment. • Implementation occurs when newly developed systems are actually up and running on the computer equipment.

  9. Systems Development Life Cycle • Systems development projects normally are undertaken by a project team. • This team is composed of system analysts, programmers, accountants, and other people who are knowledgeable about or affected by the project. • Every systems development project goes through essentially the same life cycle.

  10. Systems Development Life Cycle Analysis Design Implementation

  11. Systems Development Life Cycle • The life-cycle concept implies that each systems development project should be factored into a number of distinct phases with formal management control points. • The basic control principle is that each phase should generate documentation to be formally reviewed and approved prior to entering the next phase of a project’s life cycle.

  12. Systems Development Life Cycle General Phases Detailed Phases Analysis Feasibility assessment Information analysis Design System design Program development Implementation Conversion Operation and maintenance Audit and review

  13. Problems with Systems Development Life Cycle Wild Enthusiasm Disillusionment Total Confusion

  14. Problems with Systems Development Life Cycle Search for the Guilty Punishment of the Innocent Promotion of Nonparticipants

  15. Problems with Systems Development Life Cycle As Proposed by User Manager As Approved by the Steering Committee As Structured by the Data Administrator

  16. Problems with Systems Development Life Cycle As Implemented by the Application Programmers As Designed by the Lead Analyst What the User Actually Wanted

  17. Business Reengineering • What is business reengineering? • What has stimulated interest in business reengineering? • total quality performance (TQP), or TQM • trends in information services

  18. Business Reengineering • Business reengineering concerns business reinvention (not improvement), enhancement, or modification. • Business reengineering is concerned with multiplicative rather than marginal improvements in performance.

  19. The Role of Information Technology • Information technology is a powerful enabler of process innovation. • There are nine categories of ways in which information technology can support process innovation: • Automational support • Informational support

  20. The Role of Information Technology • Sequential support • Tracking support • Analytical support • Geographical support • Integrative support • Intellectual support • Disintermediating support

  21. Documentation Standards • Documentation standards set forth explicit requirements for the documentation to be developed during a project. • The basic concept of system development standards is to define the phases in the systems development life cycle and to specify the documents that should be generated during each phase.

  22. Overview of Systems Development Documentation • feasibility study ? • Logical flow diagrams ? • data dictionary ? • user specification ? • conceptual design report ? • systems design report ? • program description ?

  23. Overview of Systems Development Documentation • run manual ? • Data entry procedures ? • What is a conversion plan? • testing plan ?

  24. Overview of Systems Development Documentation Time Old System New System Immediate Cutover Parallel Operation Old System New System Old System Phased Conversion Module A Module B Module C Time

  25. Maintenance of Systems Documentation Standards • Maintaining systems documentation standards and using them consistently in systems development are formidable tasks. • Documentation standards my be developed in-house or purchased from a vendor. • Documentation is frequently referred to as deliverables.

  26. Analyst/Programmer Productivity Control • The major portion of total systems development costs is the salaries of analysts and programmers. • The end product of an analyst is a system design for a program, which is not as concrete as an actual program.

  27. Analyst/Programmer Productivity Control • The use of structured analysis, design, and graphic techniques should increase the overall productivity of the analyst function. • Controls suggested for improving the productivity of programmers concern the way programs are designed and coded and the organization of programming personnel.

  28. Structured Programming • What is structuring programming? • The team approach establishes a team consisting of a lead or chief programmer, assistant programmers as needed, and a programming secretary.

  29. Structured Programming • Programmer productivity may also be increased through technical aids. • Special software packages, called preprocessors, and automated documentation systems also increase programmer productivity.

  30. Computer-Aided Software Engineering (CASE) • What is computer-aided softwareengineering? Diagramming Tools Syntax Verifiers Prototyping Repository Code Generation Project Management

  31. Prototyping • What is prototyping? • Object-oriented technology includes object-oriented programming (OOP) and object- oriented databases. • The goal of object-oriented programming is to make software easier to create, simpler to use, and more reliable through reusability.

  32. Object-Oriented Technology • An objet-oriented database stores both data and the procedures that operate on the data as a single unit, that is, an object. • With object-oriented programming, common functions are defined as objects and stored in a repository. • Parent objects contain code for common functions.

  33. Program-Change Control • Program-change controls concern the maintenance of application programs. • The objective of such controls is to prevent unauthorized and potentially fraudulent changes from being introduced into previously tested and accepted programs. • Control of program changes involves documentation and review.

  34. Database Administration • A major control activity of the DBA is to establish standards and documentation for the data elements in a database. • Database administration must deal with the issues of data security, integrity, data sharing, recovery/backup, and audit trails.

  35. Planning and Organizing a Systems Project • Project selection is usually the responsibility of a steering committee or other organizationwide unit to assure active user participation in the selection process. • One important task of management is to assemble a suitable project team.

  36. Project Team Organization Steering Committee Information Systems Department User Department Project Leader User Member Lead Analysts Technical Staff Analysts/ Programmers

  37. Project Leader Responsibilities Planning Scheduling Control Project Breakdown Allocation of Resources Progress and Time Reporting Status Reporting Activity Task/ Scheduling Task Assignment

  38. Factoring a Project into Phases and Tasks New System 1.0 2.0 3.0 Analysis Design Implementation 1.2 1.1 3.1 3.2 Application Study Vendor Selection Documen- tation Equipment Delivery 2.1 2.2 2.3 Output Design Form Design Program Design

  39. Work Measurement Techniques • The simplest approach to estimation is to guess. • More rigorous approaches to estimation are based on the concept of work measurement. • Identify the tasks to be estimated. • For each task, estimate the total size or volume of the task in some suitable manner.

  40. Work Measurement Techniques • Convert the size or volume estimate into a time estimate by multiplying the size or volume estimate by a standard or estimated processing rate. • Adjust the estimated processing rate to include circumstantial considerations such as idle time, task complexity, or task newness.

  41. Accuracy of Estimates • There is general agreement on several points related to the estimation process. • Estimates are only estimates. • Accuracy of estimation improves as a project proceeds through its course of activities. • Initial estimates are frequently made too low.

  42. Project Accounting • A project accounting system is a cost accounting system in which costs are assigned to individual projects. • Effective project control requires a project accounting system that can keep track of costs incurred to date on a project and provide a summary cost report at a project’s completion.

  43. Project Accounting System Computer Usage Summaries Progress Report Time Sheets Project Accounting System Cost to Date Overhead Rates Revised Cost Estimate

  44. Project Accounting System Project Accounting System Project File Number 91-045 Costs Actual Budget Materials XXX XXX Labor XXXX XXXX Overhead XXX XXX Project Schedule

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