Wednesday, August 5, 2009

Software Engineering

Chapter 1

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Nature of Software System:

  • Ubiquitious – variety of application: business, engineering & scientific applications
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  • Simple to complex, internal to public, single function to enterprise wide, one location to distributed, batch or real-time, informational to mission critical.

Challenges in Large Projects:
lDeveloping large/complex software application is very challenging
  • Effort intensive
  • High cost
  • Long development time
  • Changing needs of users
  • High risk of failure, user acceptance, performance, maintainability
Quite different from one-time program where authors and users are the same


SUCCESSFUL SOFTWARE SYSTEM..
lS/ware development projects have not always been successful

lWhat is successful software applications?

  • Development completed
  • It is useful
  • It is usable and
  • It is used
  • Cost effectiveness and maintainability applied

REASONS FOR FAILURE
  • lSchedule slippage
  • Cost over-runs
  • Does not solve user’s problem
  • Poor quality of software
  • Poor maintainability
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Ad-hoc software development…


  • No planning (e.g. no milestones defined)
  • Deliverables to users not identified
  • Poor understanding of user requirements
  • No control or review
  • Technical or incompetence of developers
  • Poor understanding of cost and effort by both developer and user.
ENGINEERING..

  1. lRequires well-defined approach – repeatable, predictable
  2. Large projects require managing the project itself
  • Manage project, people, money (cost), equipment, schedule
  • Scale makes big difference .. Compare building hut, 2-storey house, large condominium/hotel
3. Quality extremely important: relates to failures, efficiency, usability ..
  • People are willing to pay for quality!
Large Projects…

l# Involve different types of people
  • Large building: architects, civil engineer, electrical engineer, workers (carpenters..etc)
l# Continuous supervision for quality assurance
  • On site supervisors (check cement/ steel quality.. Etc. )
l# Many deliverables: architecture plan, model, structure diagrams, electrical cabling layout etc.

l# Standards, regulations, conventions need to be followed.

l# Steps, milestones define and reviews are carried out, progress is visible





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