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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