1.1 The nature of software.ppt

models

1. THE NATURE OF SOFTWARE

2. INTRODUCTION
ComputerSoftware
Softwareistheproductorsetofinstructions.
Anythingthatcanbestoredelectronically.
SoftwareEngineering
Softwareengineeringencompassesaprocess,acollectionof
methods(practice)andanarrayoftoolsthatallowprofessionals
tobuildhighqualitycomputersoftware.

3. SOFTWARE EXAMPLES

4. Software’s Dual Role
Softwareisaproduct
Softwareisavehiclefordeliveringaproduct

5. DEFINITIONS
Softwareisdefinedas–
Instructions
Programsthatwhenexecutedprovidedesired
function
Datastructures
Enabletheprogramstomanipulateinformation
Descriptiveinformation(documents)
Describetheoperationanduseoftheprograms

6. Characteristics of Software
Softwareisdevelopedorengineered,itisnot
manufacturedintheclassicalsense.
Softwaredoesnotwearout.Howeveritdeteriorates
duetochange.
Althoughtheindustryismovingtowardscomponent
basedconstruction,mostsoftwarecontinuestobe
custombuilt.

7. FAILURE CURVE FOR HARDWARE
Time
“Infant
mortality”
“Wearout”
Failure rate

8. FAILURE CURVE FOR SOFTWARE

9. Software Application Domains
Systemsoftware
Collectionofprogramswrittentoserviceotherprograms
Applicationsoftware
Stand-aloneprogramsthatsolveaspecificbusinessneed
Engineering/scientificsoftware
Numbercrunchingalgorithm
Embeddedsoftware
Resideswithinaproductorsystemandusedtoimplementand
controlfeaturesandfunctionsfortheenduserandforthesystem
itself

10. Contd..
Product-linesoftware
Designedtoprovideaspecificcapabilityforusebymany
differentcustomers(eg.Wordprocessing,spreadsheet,
multimedia,DBmanagementsystem,etc)
Web-applications
Called“WebApps”,thisnetworkcentricsoftwarecategory
spansawidearrayofapplications
Artificialintelligencesoftware
Makesuseofnon-numericalalgorithmstosolvecomplex
problems

11. New Challenges
Open–worldcomputing
Wirelessnetworksanddistributedcomputing
Netsourcing
Webasacomputingengineandcontentprovider
Simplearchitectureacrosswww
Opensource
Freesourcecodesopentothecomputingcommunity

12. Legacy Software
Legacysoftwareareolderprogramsthataredevelopeddecades
agoandhavebeencontinuallymodifiedtomeetchangesin
businessrequirementsandcomputingplatforms
Thequalityoflegacysoftwareispoorbecauseithasinextensible
design,convolutedcode,poorandnonexistentdocumentation,test
casesandresultsthatarenotachieved

13. Legacy Software
Astimepasseslegacysystemsevolveduetofollowingreasons:
Thesoftwaremustbeadaptedtomeettheneedsofnewcomputing
environmentortechnology.
Thesoftwaremustbeenhancedtoimplementnewbusiness
requirements.
Thesoftwaremustbeextendedtomakeitinteroperablewithmore
modernsystemsordatabase
Thesoftwaremustbere-architectedtomakeitviablewithina
networkenvironment.

14. MINDMAP

15. SUMMARY
•Thenatureofsoftware
Characteristicsofsoftware
Softwareisdevelopedorengineered
Softwaredoesn'twear-out
Softwarecontinuestobecustombuilt
Softwareapplicationdomains
Systemsoftware
Applicationsoftware
Engineering/scientificsoftware
Embeddedsoftware
Product-linesoftware
Webapplications
ArtificialIntelligencesoftware
Newchallenges
Openworldcomputing
Netsourcing
Opensource
Legacysoftware

16. Stimulating Questions
Canyoudifferentiatecomputerprogramand
computersoftware?
Ans:
1)Programisasetofinstructionswhereass/wisa
setofprogramsi.e.,
2)Acomputerprogramispieceofprogramming
codewhichperformsawelldefinedtaskwhere
assoftwareincludesprogrammingcode,its
documentationanduserguide.

17. Contd..
Whenyouknowprogramming,whatistheneedto
learnsoftwareengineeringconcepts?
Ans:
•Apersonwhoknowshowtobuildawallmaynotbegoodat
buildinganentirehouse.Likewise,apersonwhocanwrite
programsmaynothaveknowledgeofotherconceptsof
SoftwareEngineering.Thesoftwareengineeringconcepts
guideprogrammersonhowtoassessrequirementsofend
user,designthealgorithmsbeforeactualcodingstarts,
createprogramsbycoding,testingthecodeandits
documentation.