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SYSTEMS ANALYSIS & DESIGN. PHASE 4 SYSTEMS IMPLEMENTATION Application Development. Chapter 10. Application Development. Introduction. During the systems implementation phase, the development team uses the system design specification as a blueprint for constructing the new system

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systems analysis design

SYSTEMS ANALYSIS & DESIGN

PHASE 4

SYSTEMS IMPLEMENTATION

Application Development

chapter 10
Chapter 10

Application Development

introduction
Introduction
  • During the systems implementation phase, the development team uses the system design specification as a blueprint for constructing the new system
  • Analysts and programmers have different roles during application development
  • An analyst's main task is to deliver clear, accurate specifications to a programmer
quality assurance
Quality Assurance
  • Quality assurance is vitally important in all business areas, including IS functions
  • The main objective of quality assurance is to detect and avoid problems as early as possible
  • Quality assurance can detect
    • Inaccurate requirements
    • Design or coding errors
    • Faulty documentation
    • Ineffective testing
quality assurance5
Quality Assurance
  • Software engineering
    • Stresses quality in software design
      • Solid design
      • Effective structure
      • Accurate documentation
      • Careful testing
quality assurance6
Quality Assurance
  • Software engineering
    • Stresses quality in software design
      • Solid design
      • Effective structure
      • Accurate documentation
      • Careful testing
    • Software Engineering Institute (SEI) http://www.sei.cmu.edu
      • Mission is to improve quality of software-based systems
      • Capability Maturity Model is designed to improve quality, reduce development time, and cut costs
application development
Application Development
  • Planning the overall design strategy
    • Use top-down (modular) approach and partition the system into subsystems and modules
  • Develop programs and modules
    • Design, code, test, and document
  • Test the system
    • Link test
    • System test
    • Complete all documentation
application development9
Application Development
  • Documentation review and application design
    • Program designs are based on
      • System design specification
      • Prior phase documentation
      • DFDs
      • Process descriptions
      • Screen layouts
      • Report layouts
      • Source documents
      • Data dictionary entries
application development10
Application Development
  • Documentation review and application design
    • Structure (hierarchy) charts
      • Show the organization of program modules and the functions they perform
    • Program flowcharts
      • Show the internal logic needed to perform program tasks and provide output
    • Pseudocode
      • Documents the program’s logical steps
application development11
Application Development
  • Programming the application
    • Process of turning program logic into specific instructions that can be executed by the computer system
application development12
Application Development
  • Testing the application
    • Testing is necessary to ensure that all programs function correctly
    • First step is to detect syntax errors and obtain a clean compilation
    • Next step is to eliminate logic errors
      • Techniques include desk checking, structured walkthrough, and code review
    • Final step is testing
      • Unit, link, and systems testing
application development14
Application Development
  • Testing the application
    • Unit testing
      • Involves an individual program
      • Objective is to identify and eliminate execution errors and any remaining logic errors
      • Stub testing is a technique of using stubs to represent entry or exit points that will be linked later to another program or data file
application development15
Application Development
  • Testing the application
    • Link testing
      • Involves two or more programs that depend on each other
      • Also called string testing, series testing, or integration testing
      • Link testing ensures that the job streams are correct
      • Test data is necessary to simulate actual conditions and test the interface between programs
application development16
Application Development
  • Testing the application
    • System testing
      • Involves the entire information system and includes all typical processing situations
      • Requires users to verify all processing options and outputs
      • Uses live data
      • Involves a final test of all programs
      • Ensures that proper documentation is ready
      • Verifies that all system components work correctly
      • Confirms that the system can handle predicted data volumes in a timely and efficient manner
tradeoff
TRADEOFF
  • How far should you go with system testing?
  • Tradeoff: pressure for the new system from users and managersvs. the need to avoid major errors
  • Typical issues to consider
    • What is the judgment of analysts, programmers, IS management, and the project manager?
    • Do potential problems exist that might affect the integrity or accuracy of data?
    • Can minor changes be treated as future maintenance items?
documentation
Documentation
  • Explains the system and helps peopleinteract with it
  • Types of documentation
    • Program documentation
    • System documentation
    • Operations documentation
    • User documentation
documentation19
Documentation
  • Program documentation
    • Begins in the systems analysis phase and continues during systems implementation
    • Includes process descriptions and report layouts
    • Programmers provide documentation with comments that make it easier to understand and maintain the program
    • An analyst must verify that program documentation is accurate and complete
documentation20
Documentation
  • System documentation
    • System documentation describes the system’s functions and how they are implemented
    • Most system documentation is prepared during the systems analysis and systems design phases
    • Documentation consists of
      • Data dictionary entries
      • Data flow diagrams
      • Screen layouts
      • Source documents
      • Initial systems request
documentation21
Documentation
  • Operations documentation
    • Typically used in a minicomputer or mainframe environment with centralized processing and batch job scheduling
    • Documentation tells the IS operations group how and when to run programs
    • Common example is a program run sheet, which contains information needed for processing and distributing output
documentation22
Documentation
  • User documentation
    • Typically includes the following items
      • System overview
      • Source document description, with samples
      • Menu and data entry screens
      • Reports that are available, with samples
      • Security and audit trail information
      • Responsibility for input, output, processing
      • Procedures for handling changes/problems
      • Examples of exceptions and error situations
      • Frequently asked questions (FAQ)
      • Explanation of Help & updating the manual
documentation23
Documentation
  • User documentation
    • Written documentation material often is provided in a user manual
    • Analysts prepare the material and users review it and participate in developing the manual
documentation24
Documentation
  • User documentation
    • Written documentation material often is provided in a user manual
    • Analysts prepare the material and users review it and participate in developing the manual
    • Online documentation can empower users and reduce the need for direct IS support
      • Context-sensitive Help
      • Interactive tutorials
      • Hints and tips
      • Hypertext
      • On-screen demos
management approval
Management Approval
  • After system testing is complete, the results are presented to management
    • Test results
    • Status of all required documentation
    • Input from users who participated
    • Detailed time schedules, cost estimates, and staffing requirements
  • If approved, a schedule for system installation and evaluation will be established