Scope of software engineering

1. Scope of Software Engineering

2. Muhammad Naveed Zafar
Educational Background
BS in Computer Science
(Bahria University)
MS in Software Project
Management
(FAST University)*
Professional Experience
Project Manager
(NevTech)
Faculty Member
(Aptech MSG)
Project Coordinator
AMI
Software Engineer
GoSafe Systems

3. Agenda
What,WhyandAspectsofSoftwareEngineering?
HorrorSoftwareFailureStories
SoftwareEngineerLineofActions
SoftwareEngineeringStakeholders
EngineeringApproach
RolesandMembersofDevelopmentTeam
ProblemSolvingParadigms
SDLCModels
BestPracticestobeAdopt
ScrumMethodologies

4. What is software?
•Computerprogramsandassociateddocumentation
•Softwareproductsmaybedevelopedforaparticular
customerormaybedevelopedforageneralmarket
•Softwareproductsmaybe
–Generic/COTS-developedtobesoldtoarangeof
differentcustomers
–Custom-developedforacustomeraccordingtotheir
specification

5. What is Engineering?
•Engineeringis…
–Theapplicationofscientificprinciplesandmethodstothe
constructionofusefulstructures.
Examples:
–Mechanicalengineering
–Computerengineering
–Civilengineering
–Chemicalengineering
–Electricalengineering
–Nuclearengineering
–Aeronauticalengineering

6. What Actually “Software Engineering”?
•Adisciplinewhoseaimintheproductionofsoftwarethat
–meetstheclient‟sneeds
–fault-free
–deliveredontime
–deliveredwithinbudget
–easytomodify

7. Why the need for Software Engineering?
SoftwareCrisis:Unacceptablelowqualityofsoftware,
exceedsdeadlineandbudget.Canceled, 23%
Successful,
28%
*Completed with
Faults, 49%
*Completed late, over budget, and/or with features missing

8. Why Software Engineering ?
•Theproblemiscomplexity
•Manysources,butsizeisakey:
–Mozillacontains3Millionlinesofcode
–UNIXcontains4millionlinesofcode
–Windows2000contains10
8
linesofcode
•Secondisrolesdefine
•Thirdisuncertaintyof“inputs”andtheirtiming
•Fourthisthecontinuingchanging“environment”anddemands.
Software engineering is about managing all the sources of complexity to
produce effective software.

9. Software Engineering Aspects
•Historical Aspects:
– ,aNATOgroupcoinedtheterm“SoftwareEngineering”
– NATOSoftwareEngineeringConferenceconcurredthat
“Softwareproductionshouldbeanengineering-likeactivity”
–Usingphilosophiesandparadigmsofestablishedengineering
disciplinestosolveSoftwareCrisisthatthequalityofsoftwarewas
generallyunacceptablylowandthatdeadlinesandcostlimitswere
notbeingmet”

10. •Economic Aspects
–SoftwareEngineeringv.s.ComputerScience
•Thecomputerscientistinvestigatesseveralwaystoproduce
software,somegoodandsomebad
•But the software engineeris interested in only those techniques
that make sound economicsense.
For example:A coding technique that can execute very efficiently
but with higher maintenance cost may not be a good choice, since
maintenance occupies a lot of resources of the whole life cycle.
Software Engineering Aspects…

11. •Maintenance Aspects
–SoftwareLifeCycle/SoftwareProcess
•RequirementsPhase
•Specification(Analysis)Phase
•PlanningPhase
•DesignPhase
•ImplementationPhase
•IntegrationPhase
•MaintenancePhasehighestcostamongallthesephases)
•Retirement
Software Engineering Aspects…

12. Requirement 2%
Specification 4%
Planning 1%
Design 6%
Module Coding 5%
Module Testing 7%
Integration 8%
Maintenance
67% Maintenance Aspects
Maintenance
Approximate relative costs
ofthe phases of the software
life cycle.
Maintenanceissoimportantthatamajoraspectofsoftware
engineeringconsistsoftechniques,tools,andpracticesthatleadtoa
reductioninmaintenancecost

13. Horror Software Failure Stories
•Patientsdiedasaconsequenceofsevereoverdosesof
radiation.
•USTreasuryDepartmentmailedincorrectlyprintedSocial
SecurityChecks.
•Interestmiscalculatedonstudentloansresultinginhigher
monthlypayments.
•MarsClimateOrbiterspacecraftcrashesintothesurfaceof
Marsbecauseofmeasurementconversionerror.
Consequences of software failures range from inconvenienceto death!

14. Software Engineer Line of Actions
SoftwareEngineersshould
–adoptasystematicandorganisedapproachtoallaspects
ofsoftwaredevelopment.
–useappropriatetoolsandtechniquesdependingon
•theproblemtobesolved,
•thedevelopmentconstraintsand
•theresourcesavailable
–Understandandcommunicateprocessesforimproved
softwaredevelopmentwithintheirorganization
–Beeffectiveteammembersand/orleaders.
–Canbeverytechnicalormoremanagerialdependingon
organizationalneed.

15. Where Does the Software Engineer Fit In?
•Computer Science: focusing on computer
hardware,compilers,operatingsystems,andprogramming
languages
•SoftwareEngineering:adisciplinethatusescomputerand
softwaretechnologiesasaproblem-solvingtools

16. Where Does the SW Engineer Fit in?...
Relationship between Computer Science and Software Engineering

17. Qualities of Good Software?
•Goodsoftwareengineeringmustalwaysincludeastrategy
forproducingqualitysoftware
•Threewaysofconsideringquality
–Thequalityoftheproduct
–Thequalityoftheprocess
–Thequalityoftheproductinthecontextofthebusiness
environment

18. Who Does Software Engineering?
•Customer:thecompany,organization,orpersonwhopays
forthesoftwaresystem
•Developer:thecompany,organization,orpersonwhois
buildingthesoftwaresystem
•User:thepersonorpeoplewhowillactuallyusethesystem

19. Who Does Software Engineering? (continued)
Participants (stakeholders) in a software development project

20. Engineering Approach
Building a System
•Requirementanalysisanddefinition
•Systemdesign
•Programdesign
•Writingtheprograms
•Unittesting
•Integrationtesting
•Systemtesting
•Systemdelivery
•Maintenance

21. Members of the Development Team
•RequirementAnalysts:workwiththecustomerstoidentifyanddocumentthe
requirements
•Designers:generateasystem-leveldescriptionofwhatthesystemus
supposedtodo
•Programmers:writelinesofcodetoimplementthedesign
•Testers:catchfaults
•Trainers:showusershowtousethesystem
•MaintenanceTeam:fixfaultsthatshowuplater
•Librarians:prepareandstoredocumentssuchassoftwarerequirements
•ConfigurationManagementTeam:maintaincorrespondenceamongvarious
artefacts.

22. Members of the Development Team
(continued)
Typical roles played by the members of a development team

23. Secrets of Successful Projects

24. Problem Solving Paradigms
Severaltechniqueshavebeensuggestedtohelpsolvethesoftware
crisis
–~ - :StructuredParadigm
•StructuredSystemsAnalysis,Composite/StructuredDesign,Structured
Programming,StructuredTesting
•Leadtomajorimprovementsforsoftwareindustry
•Butonlygoodforsmallprograms(say,,-,linesofcodes)
•Notsogoodinsoftwaremaintenanceaspects,(forinstance,becauseofthe
separationofaction-orientedanddata-orientedinstructuredparadigm)
–Object-OrientedParadigm
•Anobjectisaunifiedsoftwarecomponentthatincorporatesbothdataand
actionsthatoperateofthosedata-->MorePromising!

25. Why use Object Oriented Paradigm?
•ClassicalStructuredParadigm
–Focusonfunctionsofsystem
•Object-OrientedParadigm
–Focusonobjects
–Implementationdetailsarelocaltotheobject
•Regressionfault(faultproducedbyseemingunrelatedchange)is
greatlyreduced.
–Encapsulation:well-designedindependentunits
–PotentialReuseofobjectsreducestimeandcost

26. The Software Process
•Astructuredsetofactivitiesrequiredtodevelopasoftwaresystem
–Specification;
–Design;
–Validation;
–Evolution.
•Asoftwareprocessmodelisanabstractrepresentationofaprocess.
•Itpresentsadescriptionofaprocessfromsomeparticularperspective.

27. Waterfall ModelSystem
Engineering
Analysis
Design
Code
Testing
Maintenance

28. Waterfall Model Characteristics
•Theclassiclifecycle-oldestandmostwidelyusedparadigm
•Activities„flow‟fromonephasetoanother
•Iftherearecorrections,returntoapreviousphaseand„flow‟from
thereagain
•Majoradvantages:Goodforplanningandwelldefined/repeatedprojects

29. Problems of Waterfall Model
•Realprojectsoftenfollowthesequence
•Allrequirementsmaynotbestatedexplicitlybycustomer
•Customeronlyseestheresultsaftersometime
•Developersareoftendelayedatcertainphases

30. Rapid Application Development (RAD)
Business
Modeling
Data
Modeling
Process
Modeling
Application
Generation
Testing &
Turnover
Team #1
Business
Modeling
Data
Modeling
Process
Modeling
Application
Generation
Testing &
Turnover
Team #2
Time period

31. RAD Characteristics
•“High-speed”versionofwaterfallmodel
•Primarilyforinformationsystemsapplications
•Requirementswell-understood,fullyfunctionalsystemproducedin
shorttime
•Theapplicationmodularized-majorfunctionscanbecompletedin3
months
•Separateteamscompletethefunctions,thenintegratedasawhole
•Requireshumanresourceandcommitment

32. Scrum Agile Methodologies

33. Importance of Continual Planning,
Testing, Documentation
•Aftercustomerhassignedoffonthespecifications,continuetomonitor
andadjustplan.
•Softwaremustbefault-freeaspossibleatalltimes.
•Atalltimes,documentationmustbecomplete,correctandup-to-date.
–personneloverturn
–incompleteimplementation
–inaccuratetesting
–impossibletomaintain

34. Conclusion
•TipstoSolveaproblem
–AnalyseProblems
–Synthesizeasolution
•Understandthatrequirementsmaychange
•Mustviewqualityfromseveraldifferentperspectives
•Usefundamentalsoftwareengineeringconcepts
•Keepsystemboundaryinmind

35. Thank you