Prototyping-Software Requirement-Lecture Slides, Slides of Software Project Management

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PrototypingLecture # 21

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Prototyping

• It is the technique of constructing a

partial implementation of a system sothat customers, users, or developerscan learn more about a problem or asolution to that problem

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Prototype - 2

• In hardware systems, prototypes are

often developed to test and experimentwith system designs

• In software systems, prototypes are

more often used to help elicit andvalidate the system requirements.There are other uses also

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Prototype - 3

• It should be easy for a prototype to be

developed quickly, so that it can be usedduring the development process

• Prototypes are valuable for requirements

elicitation because users can experimentwith the system and point out its strengthsand weaknesses. They have somethingconcrete to criticize

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Throw-away Prototyping - 1

• Intended to help elicit and develop the

system requirements

• The requirements which should be

prototyped are those which cause mostdifficulties to customers and which arethe hardest to understand. Littledocumentation is needed

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Throw-away Prototyping - 2

• Determine the feasibility of a

requirement

• Validate that a particular function is

really necessary

• Uncover missing requirements• Determine the viability of a user

interface

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Throw-away Prototyping - 4

• Writing the real SRS• Developing the real product

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Evolutionary Prototyping - 1

• Intended to deliver a workable system

quickly to the customer

• The requirements which should be

supported by the initial versions of thisprototype are those which are well-understood and which can deliveruseful end-user functionality

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Evolutionary Prototyping - 3

• Evolutionary prototype may not be

built in a ‘dirty’ fashion. Theevolutionary prototype evolves into thefinal product, and thus it must exhibitall the quality attributes of the finalproduct

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Comparison of Prototyping - 1

Throwaway

Evolutionary

Developmentapproach

Quick anddirty. Norigor

No sloppiness.Rigorous

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Comparison of Prototyping - 3

Throwaway

Evolutionary

Design drivers Optimize

developmenttime

Optimizemodifiability

Ultimate goal

Throw it away Evolve it

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Prototyping Benefits - 1

• The prototype allows users to

experiment and discover what theyreally need to support their work

• Establishes feasibility and usefulness

before high development costs areincurred

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Prototyping Costs

• Training costs
  • Prototype development may require the

use of special purpose tools

• Development costs
  • Depend on the type of prototype being

developed

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Prototyping Problems - 1

• Extended development schedules
  • Developing a prototype may extend the

schedule although the prototyping timemay be recovered because rework isavoided