Introduction to Software Engineering

[jimin-kiim]

• properties of good software program; casually listing
• software life cycle
• goal of Software Engineering
• software properties

[jimin-kiim]

Properties of good software program; casually listing

• correctness_ correctly satisfying user requirement/specification
• efficiency(space, time)
• maintainability
  • readability
  • extensibility, scalability
  • reusability
  • portability(platform-independent)
  • easy to debug
  • easy to test
  • easy to modify
• stability
• reliability
• usability
• conciseness
• security
• completeness
• consistency
• well documented
• well structured

<->

• unmanageable
• difficult to maintain
• over-budget&time
• poor quality
• do not meet requirements sufficiently => cause complexity

Software Crisis

• rapid increases in computer power and the complexity of the problems
• the difficulty of writing correct, understandable and verifiable computer programs

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Software Life Cycle

1. Analyzing Requirements

• problem specification

  2. Designing

• program structure
• module specification
• transform the description into SW layout
• design data structures in each component
• transform behavior description into algorithms

  3. Constructing(Implementation)

  • implementing components
• implement the desired activities in each component
• with unit testing, subsystems are validated individually
  • identify necessary conditions for correct functioning
  • test input values to verify SW component will perform correctly when presented with legal input values
  • integration of components
• components are slowly integrated into completed system, using stubs as yet unimplemented parts.
  • stubs
    • simple dummy routines with no behavior or with very limited behavior
    • can be temporary substitute for yet-to-be-developed code.
• errors discovered during integration cause reinvestigation of validation techniques performed at the subsystem level.

  4. Testing

• unit test
• integration test

  5. Maintaining

  Software Maintenance

  • activities subsequent to the delivery of the initial working version of SW system.
  • SW doesn't remain fixed after the first working version is released
  • good SW design recognizes the inevitability of changes and plans an accommodation for them from the very beginning

    90% of the costs of a typical system arise in the maintenance phase any successful piece of software will inevitably be maintained

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Software Engineering

📄 definition

• the establishment and use of a sound engineering principles in order to economically obtain the software that is reliable and works efficiently.
• the application of a systematic, disciplined, quantifiable approach to the development, operation and maintenance of software

🎯 goals

• to produce a correct, efficient and reliable software

• to minimize the cost of the software development and maintenance phase

• Maintainability the abiliity to easily make changes, enhancements or improvements

• Dependability the ability to rely on the software to function properly when needed

• Efficiency the ability to use computing resources effectively

• Usability the ability for the end user to easily and effectively use the software

[jimin-kiim]

Software Properties

• Modularity
• Encapsulation
• Localization
• Abstraction
• Uniformity
• Completeness
• Confirmability