Chapter 6 Rapid Prototyping Methodology for Systems Design130.18.86.27/faculty/warkentin/secure/slides/Chap06.pdf · Formal vs. Informal Prototyping Informal Prototyping usually from

Chapter 6Rapid Prototyping Methodology for Systems Design

page 1Copyright 2005, Merrill Warkentin

Prototyping Methodology

Professor Merrill WarkentinMississippi State University

© Copyright, Merrill Warkentin, 20042

Major Topics

prototyping concepts

types of prototypes (approaches)

prototyping and the SDLC

prototype development guidelines

prototype evaluation

rapid application development (RAD)


Today’s Topics

four approaches

development

advantages

disadvantages

users’ role


Prototyping

information-gathering techniqueuseful in seeking user reactions

user suggestionsinnovationsrevision plans

alternative to SDLC


Kinds of Information Sought

user reactionsuser suggestionspossible innovationsrevision plansnext steps


System Prototypes

alternative to pre-specification

typically faster than traditional SDLC

“quick and dirty” system

best suited for user uncertainty

first look leads to exact specification

iterative, incremental approach




Prototyping Process

quickly develop working modelget users’ feedback and inputcan be tweaked and revised

incremental iterations, user involvementshortens systems development backlogcan increase risk of incompatibility and other unforeseen mishaps


Prototyping


Prototyping

Figure 15.13 When to prototype and when not to prototype


Prototyping Categories

“throw-away prototypes” (discovery prototypes)using rapid prototyping tools or VB or othersget initial feedback from user(s)then switch to actual development language

“version 0 prototypes” (reusable prototypes)get initial feedback from user(s)iterate (incrementally add new features)then get more feedback and revise again


Four Approaches

patched-upworking model of the systeminefficient

non-operationalnon working scale modeltest certainaspects ofdesign

first-of-a-seriesfirst full-scale modelpilot

selected featuresoperational modelIncludes certain features


Formal vs. Informal Prototyping

Informal Prototypingusually from user walk-throughpen and paper sketches/drawings/diagramsinput or output “mock-ups” (not working)

Formal Prototyping - electronicusing programming languages (VB, etc.)using 4GL tools for rapid app developmentusing CASE tools




Patched-up Prototype

working model with all the features

users can interact with the system

data storage & retrieval inefficient

workable but inefficient

may contain onlybasic features


Nonoperational Scale Models

not operational,except for certain featuresto be tested

prototype input andoutput


First Full-Scale Models

create a pilot systemoperation modeluseful when many installationsof the same IS are plannedexample: a system to be installed in one location, tested and modified as necessary, and later implemented in other locations


Selected Features Prototype

operational model that includes some, not all, final system featuresexcept these features, later essential features are addedsome menu items are availablesystem built in modulespart of the actual system


Alternative to SDLC?

Should prototyping be consideredas an alternative to the systems development life cycle (SDLC)


Complaints about SDLC

time requirements / costmany lengthy steps in life cycle

user requirements change

prototyping alternative?




Risk of prototyping over SDLC

premature shaping of system

lack of formal requirements analysisoverlook important features

system adequate forinvolved users butnot for overall needs


Integration

best bet is to integrate prototypinginto SDLC life cycle


Suitability of prototypeLess Suitable for

PrototypingMore Suitable for

Prototyping

Similar Design Experience few times beforemany times before

Environment uncertaincertain

Decision Making unstructuredstructured


Development Guidelines

work in manageable modules

build the prototype rapidly

modify in successive iterations

stress the user interface


Prototyping Advantages

saves moneygreater user involvement

designed for users needshelps train users early

early testing of performancesystem can be changed early

in its developmenteasy to scrapundesirable system


Prototyping Disadvantages

discourages careful documentation

adopting an incomplete system as complete

difficult to manage the project (rapid, iterative)

requires feedback




Practice Question - THINK

Prototyping is more appropriate when:

a. the environment is stable.b. the problem is semistructured.c. the problem is structured.d. the system is complex.


Users’ Role in Prototyping

honest involvement vital

types of involvementexperimentation with prototypeopen reactionsadditions/deletions suggestions


Rapid Application Development

also known as RAD

object-oriented approach tosystems development

includes method of development

includes software tools


RAD Phases

requirements planning

RAD design workshop

implementation


Requirements Planning Phase

users and analysts meet to identify objectives of the application or system

oriented toward solving business problems


RAD Design Workshop

design and refine phaseuse group decision support systemsto help users agree on designsprogrammers and analysts can build and show visual representations of thedesigns and workflow to usersusers respond to actual working prototypesanalysts refine designed modulesbased on user responses




Implementation Phase

as the systems are built and refined, the new systems or partial systems are tested and introduced to the organization

when creating new systems, there is no need to run old systems in parallel


RAD and the SDLC

RAD tools are used to generate screens and exhibit the overall flow of the application

users approve the design and sign offon the visual model

implementation is less stressful sinceusers helped to design the business aspects of the system


When to Use RAD

team includes programmers and analysts who are experienced with RAD

pressing reasons for speeding upapplication development

project involves a novel ecommerce application and needs quick results

users are sophisticated and highlyengaged with company goals


Disadvantages of RAD

may try and hurry the project too much

loosely documented

may not address pressingbusiness problems

potentially steep learning curve for programmers inexperienced with RAD tools


Extreme Programming (XP)

takes good systems development practices to the extreme four values of extreme programming are:

communicationsimplicityfeedbackcourage


Five XP Principles

providing rapid feedback

assuming simplicity

changing incrementally

embracing change

encouraging quality work




Five XP Principles


Four Basic Activities of XP

coding

testing

listening, to the programming partner and customer

designing


Four XP Resource Control Variables

time

cost

scope

quality


Four XP Core Practices

short releases, work with the most important features first

having a 40-hour work week

having an onsite customer

pair programming with another programmer


XP Relationships


XP Development Process

exploration

planning

iterations to the first release

productionizing

maintenance




XP Stories

XP stories are a spoken interaction between developers and users

not written communication

the goal is prevention of misunderstanding or misinterpretations of user requirements


XP Lessons

The six lessons that can be drawn from the XP development approach are:

short releases allow the system to evolve

pair programming enhances overall quality

onsite customers are mutually beneficial to the business and the XP team


XP Lessons

The six lessons that can be drawn from the XP development approach (continued)

the 40-hour work week improves worker effectiveness

balanced resources and activities support project goals

XP values are crucial to success


XP Lessons


Agile Modeling

similar to XP

in addition to the values of communication, simplicity feedback and courage, has a fifth value of humility


Agile Modeling (Continued)

listen to user stories

draw a logical workflow model

create new user stories based on the workflow

develop some prototypes

use feedback from the prototypes and logical workflow to create physical model




Scrum

an Agile approach that has an emphasis on teamwork

team success is of primary importance

individual success is secondary

the team works within a strict time frame

the project leader has some but not much influence on detail


Summary

four approachesdevelopmentadvantagesdisadvantagesusers’ roleRADXPAgile

Copyright NoticeThis document may not, in whole or part,

be copied, photocopied, reproduced, translated, transmitted,

or reduced to any electronic medium or machine readable form without explicit permission and written authorization

from Dr. Merrill Warkentin.

[email protected]

MISProfessor.com

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Chapter 6 Rapid Prototyping Methodology for Systems Design130.18.86.27/faculty/warkentin/secure/slides/Chap06.pdf · Formal vs. Informal Prototyping Informal Prototyping usually from