Introduction to Software Engineering

1
Introduction to Software Engineering
2
Programming versus Software Engineering

• programming
• 1. The process of translating a problem from its
  physical environment into a language that a
  computer can understand and obey. (Websters New
  World Dictionary of Computer Terms)
• 2. The art of debugging a blank sheet of paper.
  
• 3. A pastime similar to banging one's head
  against a wall, but with fewer opportunities for
  rewards. (2 and 3 from The New Hackers
  Dictionary)
• software engineering (according to Fritz Bauer)
• The establishment and use of sound
  engineering principles in order to obtain
  economically software that is reliable and works
  efficiently on real machines.

3
Other Definitions of Software Engineering

• A systematic approach to the analysis, design,
  implementation and maintenance of software. (The
  Free On-Line Dictionary of Computing)
• The systematic application of tools and
  techniques in the development of computer-based
  applications. (Sue Conger in The New Software
  Engineering)
• Software Engineering is about designing and
  developing high-quality software. (Shari
  Lawrence Pfleeger in Software Engineering -- The
  Production of Quality Software)

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Software Engineering is Nothing New

• In 1945 George Polya Published a Book
• Called How to Solve It Outlining Four
• Steps in Problem Solving.
• 1. Understand the Problem (Requirements
• Analysis)
• 2. Devise a Plan (Software Design and
• Implementation Plan)
• 3. Carry out the Plan (Coding)
• 4. Look Back (Testing the Solution)

5
Development Costs

• Analysis by Capers Jones

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The Origin of Software Defects
7
Maintenance Costs
8
Development Schedules

• For Large Companies
• 30 of software projects are canceled before
  completion
• 62 experience significant cost /schedule
  overruns and/or offer fewer features than
  originally specified
• Less than 9 finish on time, within budget, and
  satisfy user needs
• The mode is to finish over a year late and cost
  almost twice original estimates