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PrinciplesofSo3wareConstruc9on: Objects,Design,andConcurrencySo3wareengineeringinprac9ceConfigura9onmanagementandversioncontrolsystemsJoshBlochCharlieGarrodDaryaMelicher

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Administrivia

•  Homework6duenextWednesday–  CheckpointdeadlineMondaynight

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KeyconceptsfromThanksgiving

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KeyconceptsfromlastTuesday

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Streamsdesigndiscussion

•  RecallthefundamentalAPIdesignprinciples…

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Majortopicsin17-313(Founda9onsofSE)

•  Processconsidera9onsforso3waredevelopment•  Requirementselicita9on,documenta9on,andevalua9on•  Designforqualitya[ributes•  Strategiesforqualityassurance•  Empiricalmethodsinso3wareengineering•  Timeandteammanagement•  Economicsofso3waredevelopment

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Test-drivendevelopment(TDD),informally

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Empiricalmethodsinso3wareengineering

•  Howdowestudytheeffec9venessoftest-drivendevelopmentcomparedtoothermethodologies?

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Thisweek:DevOps(Developmentopera9ons)

•  Introduc9ontodevops•  Configura9onmanagementandversioncontrol

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Consider:9melinesoftradi9onalso3waredevelopment

Source:ByPaulire-Ownwork,CCBY-SA4.0,h[ps://commons.wikimedia.org/w/index.php?curid=46634740

e.g.,theMicroso3*OSdevelopmenthistory

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ComparetotheUbuntureleasecycle

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ComparetotheFacebookreleasecycle

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DevOps:Development/Opera9ons

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DevOpstoolchain

•  Code:codedevelopmentandreview,sourcecodemanagementtools

•  Build:con9nuousintegra9ontools,buildstatus•  Test:con9nuoustes9ngtoolsprovidefeedback•  Package:ar9factrepository,applica9onpre-deploymentstaging

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DevOpsecosystems…

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Consider:Con9nuousintegra9on(CI)

•  AdvantagesanddisadvantagesofCI?

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Real-worldso3waredevelopmentchallenges

•  Imagine:Youdiscoverabuginversion8.2.4ofyourso3ware–  Youwanttodiscover,fix,anddeployupdatestooldversions–  Youwanttofixthebugfornewversionsinongoingdevelopment

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Configura9onmanagement(CM)

•  Defini9on(Pressman):Configura*onmanagement“isasetoftrackingandcontrolac*vi*esthatareini*atedwhenaso9wareengineeringprojectsbeginsandterminateswhenso9wareistakenoutofopera*on.”

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Reasonsforconfigura9onmanagement

•  So3wareevolu9on•  Separatedevelopment•  Audits(legal,regulatory)•  Productlines•  Marketvaria9on(e.g.,U.S.,Europe,Asia)•  Plaformvaria9on(e.g.,Android,iOS)

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Configura9onmanagementinthemodernworld

Version control

+ workflows

Build managers

Package managers

App markets

+ update

managers

Deployment managers

+ VMs/

containers

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Aside:Seman9cversioningforreleases

•  GivenaversionnumberMAJOR.MINOR.PATCH,incrementthe:–  MAJORversionwhenyoumakeincompa9bleAPIchanges,–  MINORversionwhenyouaddfunc9onalityinabackwards-compa9ble

manner,and–  PATCHversionwhenyoumakebackwards-compa9blebugfixes.

•  Addi9onallabelsforpre-releaseandbuildmetadataareavailableasextensionstotheMAJOR.MINOR.PATCHformat.

h[p://semver.org/

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Brancheswithinso3warerepositories

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Centralizedversioncontrol

•  Singleservercontainsalltheversionedfiles

•  Clientscheckout/infilesfromthatcentralplace

•  E.g.,CVS,SVN(Subversion),andPerforce

https://git-scm.com/book/en/v2/Getting-Started-About-Version-Control

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Distributedversioncontrol

•  Clientsfullymirrortherepository–  Everycloneisafullbackupof

allthedata

•  E.g.,Git,Mercurial,Bazaar

https://git-scm.com/book/en/v2/Getting-Started-About-Version-Control

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SVN(le3)vs.Git(right)

•  SVNstoreschangestoabaseversionofeachfile

•  Versionnumbers(1,2,3,…)areincreasedbyonea3ereachcommit

•  Gitstoreseachversionasasnapshot

•  Iffileshavenotchanged,onlyalinktothepreviousfileisstored

•  EachversionisreferredbytheSHA-1hashofthecontents

https://git-scm.com/book/en/v2/Getting-Started-About-Version-Control

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Aside:Gitfilestatus

© Scott Chacon “Pro Git”

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Aside:Gitinternals

© Scott Chacon “Pro Git”

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Aside:Gitobjectgraph

© Scott Chacon “Pro Git”

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Aside:Whichfilestomanage?

•  Allcodeandnoncodefiles–  Javacode–  Buildscripts–  Documenta9on

•  Exclude:generatedfiles(.class,…)–  Mostversioncontrolsystemshaveamechanismtoexcludefiles

(e.g.,.gi9gnore)

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Next9me…

•  Prac9calGit