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PrinciplesofSoftwareConstruction: Objects,Design,andConcurrencyPart1:IntroductionCourseoverviewandintroductiontosoftwaredesignJoshBloch CharlieGarrod

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Softwareiseverywhere

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Growthofcodeandcomplexityovertime

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Blackout of 2003 Normal night-time image

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PrinciplesofSoftwareConstruction: Objects,Design,andConcurrencyPart1:IntroductionCourseoverviewandintroductiontosoftwaredesignJoshBloch CharlieGarrod

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binary tree

graph search

sorting

primes

GCD

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Our goal: understanding both the building blocks and the design principles for construction of software systems

Fromprogramstosystems

Writingalgorithms,datastructuresfromscratch

Functionswithinputs

andoutputsSequentialandlocal

computation

Fullfunctionalspecifications

Reuseoflibraries,frameworks

Asynchronousandreactivedesigns

Parallelanddistributed

computationPartial,composable,

targetedmodels

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PrinciplesofSoftwareConstruction: Objects,Design,andConcurrencyPart1:IntroductionCourseoverviewandintroductiontosoftwaredesignJoshBloch CharlieGarrod

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Objectsintherealworld

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Object-orientedprogramming

•  Programmingbasedonstructuresthatcontainbothdataandmethods

publicclassBicycle{privatefinalWheelfrontWheel,rearWheel;privatefinalSeatseat;privateintspeed;…publicBicycle(…){…}publicvoidaccelerate(){speed++;}publicintspeed(){returnspeed;}}

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PrinciplesofSoftwareConstruction: Objects,Design,andConcurrencyPart1:IntroductionCourseoverviewandintroductiontosoftwaredesignJoshBloch CharlieGarrod

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Semesteroverview

•  IntroductiontoJavaandO-O•  Introductiontodesign

–  Designgoals,principles,patterns•  Designingclasses

–  Designforchange–  Designforreuse

•  Designing(sub)systems–  Designforrobustness–  Designforchange(cont.)

•  Designcasestudies•  Designforlarge-scalereuse•  Explicitconcurrency

•  Crosscuttingtopics:–  Moderndevelopmenttools:

IDEs,versioncontrol,buildautomation,continuousintegration,staticanalysis

–  Modelingandspecification,formalandinformal

–  Functionalcorrectness:Testing,staticanalysis,verification

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Sorting with a configurable order, version A

staticvoidsort(int[]list,booleanascending){…booleanmustSwap;if(ascending){mustSwap=list[i]>list[j];}else{mustSwap=list[i]<list[j];}…}

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Sorting with a configurable order, version B interfaceOrder{booleanlessThan(inti,intj);}classAscendingOrderimplementsOrder{publicbooleanlessThan(inti,intj){returni<j;}}classDescendingOrderimplementsOrder{publicbooleanlessThan(inti,intj){returni>j;}}staticvoidsort(int[]list,Orderorder){…booleanmustSwap=order.lessThan(list[j],list[i]);…}

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Sorting with a configurable order, version B'

interfaceOrder{booleanlessThan(inti,intj);}finalOrderASCENDING=(i,j)->i<j;finalOrderDESCENDING=(i,j)->i>j;staticvoidsort(int[]list,Orderorder){…booleanmustSwap=order.lessThan(list[j],list[i]);…}

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Which version is better?

staticvoidsort(int[]list,booleanascending){…booleanmustSwap;if(ascending){mustSwap=list[i]>list[j];}else{mustSwap=list[i]<list[j];}…}

interfaceOrder{booleanlessThan(inti,intj);}finalOrderASCENDING=(i,j)->i<j;finalOrderDESCENDING=(i,j)->i>j;staticvoidsort(int[]list,Orderorder){…booleanmustSwap=order.lessThan(list[j],list[i]);…}

Version A:

Version B':

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It depends?

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Software engineering is the branch of computer science that creates practical, cost-effective solutions to computing and information processing problems, preferably by applying scientific knowledge, developing software systems in the service of mankind.

Software Engineering for the 21st Century: A basis for rethinking the curriculum Manifesto, CMU-ISRI-05-108

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Software engineering is the branch of computer science that creates practical, cost-effective solutions to computing and information processing problems, preferably by applying scientific knowledge, developing software systems in the service of mankind. Software engineering entails making decisions under constraints of limited time, knowledge, and resources…

Engineering quality resides in engineering judgment… Quality of the software product depends on the engineer’s faithfulness to the engineered artifact… Engineering requires reconciling conflicting constraints… Engineering skills improve as a result of careful systematic reflection on experience… Costs and time constraints matter, not just capability…

Software Engineering for the 21st Century: A basis for rethinking the curriculum

Manifesto, CMU-ISRI-05-108

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Goalofsoftwaredesign

•  Foreachdesiredprogrambehaviorthereareinfinitelymanyprograms–  Whatarethedifferencesbetweenthevariants?–  Whichvariantshouldwechoose?–  Howcanwecreateavariantwithdesiredproperties?

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Metricsofsoftwarequality,i.e.,designgoals

Functionalcorrectness Adherenceofimplementationtothespecifications

Robustness Abilitytohandleanomalousevents

Flexibility Abilitytoaccommodatechangesinspecifications

Reusability Abilitytobereusedinanotherapplication

Efficiency Satisfactionofspeedandstoragerequirements

Scalability Abilitytoserveasthebasisofalargerversionoftheapplication

Security Levelofconsiderationofapplicationsecurity

Source: Braude, Bernstein, Software Engineering. Wiley 2011

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AtypicalIntroCSdesignprocess

1.  Discusssoftwarethatneedstobewritten2.  Writesomecode3.  Testthecodetoidentifythedefects4.  Debugtofindcausesofdefects5.  Fixthedefects6.  Ifnotdone,returntostep1

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Bettersoftwaredesign

•  Thinkbeforecoding:broadlyconsiderqualityattributes–  Maintainability,extensibility,performance,…

•  Propose,considerdesignalternatives–  Makeexplicitdesigndecisions

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Usingadesignprocess

•  Adesignprocessorganizesyourwork•  Adesignprocessstructuresyourunderstanding•  Adesignprocessfacilitatescommunication

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Preview:Designgoals,principles,andpatterns

•  Designgoalsenableevaluationofdesigns–  e.g.maintainability,reusability,scalability

•  Designprinciplesareheuristicsthatdescribebestpractices–  e.g.highcorrespondencetoreal-worldconcepts

•  Designpatternscodifyrepeatedexperiences,commonsolutions–  e.g.templatemethodpattern

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PrinciplesofSoftwareConstruction: Objects,Design,andConcurrencyPart1:IntroductionCourseoverviewandintroductiontosoftwaredesignJoshBloch CharlieGarrod

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Concurrency

•  Roughly:doingmorethanonethingatatime

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Summary:Coursethemes

•  Object-orientedprogramming•  Code-leveldesign•  Analysisandmodeling•  Concurrency

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SoftwareEngineering(SE)atCMU

•  17-214:Code-leveldesign–  Extensibility,reuse,concurrency,functionalcorrectness

•  17-313:Humanaspectsofsoftwaredevelopment–  Requirements,teamwork,scalability,security,scheduling,costs,risks,

businessmodels

•  17-413Practicum,17-415Seminar,Internship•  Variouscoursesonrequirements,architecture,software

analysis,SEforstartups,SEforML,APIdesign,etc.•  SEminorandSEconcentration:

–  https://isri.cmu.edu/education/undergrad

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COURSEORGANIZATION

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Thesearenotnormaltimes…

•  Hybridvs.in-personvs.remote•  Overallstudentexperience•  Waitlistissues•  Pre-semestersurvey:https://forms.gle/6okA6utwCsenxXcL8

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Preconditions

•  15-122orequivalent–  Twosemestersofprogramming–  KnowledgeofC-likelanguages

•  21-127or15-151orequivalent–  Familiaritywithbasicdiscretemathconcepts

•  Specifically:–  Basicprogrammingskills–  Basic(formal)reasoningaboutprograms

•  Pre/postconditions,invariants,formalverification–  Basicalgorithmsanddatastructures

•  Lists,graphs,sorting,binarysearch,etc.

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Learninggoals

•  Abilitytodesignandimplementmedium-scaleprograms•  UnderstandingOOprogrammingconcepts&designdecisions•  Proficiencywithbasicqualityassurancetechniquesfor

functionalcorrectness•  Fundamentalsofconcurrency•  Practicalskills

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Coursestaff

•  JoshBlochjbloch@gmail.comhttps://bit.ly/32J52av

•  CharlieGarrod

charlie@cs.cmu.eduhttps://bit.ly/3lviI1z

•  Teachingassistants:Alice,Ashley,Daniel,Jiasheng,Michelle,Nathaniel,

Olivia,Valentine,andSean

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Coursestaff

•  JoshBlochjbloch@gmail.comhttps://bit.ly/32J52av

•  CharlieGarrod

charlie@cs.cmu.eduhttps://bit.ly/3lviI1z

•  Teachingassistants:Alice,Ashley,Daniel,Jiasheng,Michelle,Nathaniel,

Olivia,Valentine,andSean

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Coursemeetings

•  Lectures:TuesdayandThursday,4:00–5:20pm•  Recitations:Wednesdays10:30am-…-8:30pm

–  Supplementarymaterial,hands-onpractice,feedback–  Bepreparedtoworkonpaperandwithalaptop

•  OfficehoursandZoomlinks:seecoursewebpage–  https://www.cs.cmu.edu/~charlie/courses/17-214/

Synchronous attendance is required unless you have permission for asynchronous attendance

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Infrastructure

•  Coursewebsite:http://www.cs.cmu.edu/~charlie/courses/17-214–  Schedule,officehourscalendar,lectureslides,policydocuments

•  Tools–  Git,Github:Assignmentdistribution,hand-in,andgrades–  Piazza:Discussionboard–  IntelliJorEclipse:Recommendedforcodedevelopment(otherIDEsarefine)–  Gradle,Travis-CI,Checkstyle,SpotBugs:Practicaldevelopmenttools

•  Firstrecitationistomorrow–  IntroductiontoJavaandthetoolsinthecourse–  InstallGit,Java,someIDE,Gradlebeforehand

•  Assignments–  Homework1availabletomorrow

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Textbooks

•  Requiredcoursetextbooks(electronicallyavailablethroughCMUlibrary):–  JoshuaBloch.EffectiveJava,ThirdEdition.

Addison-Wesley,ISBN978-0-13-468599-1.–  CraigLarman.ApplyingUMLandPatterns.3rd

Edition.PrenticeHall,ISBN978-0321356680.

•  Additionalreadingsondesign,Java,andconcurrencyonthecoursewebpage

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Approximategradingpolicy

•  50%assignments•  20%midtermexams(2x10%each)•  20%finalexam•  10%quizzesandparticipation

Thiscoursedoesnothaveafixedlettergradepolicy;i.e.,thefinallettergradeswillnotbeA=90-100%,B=80-90%,etc.

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Collaborationpolicy(alsoseethecoursesyllabus)

•  Weexpectyourworktobeyourown–  Youmustclearlyciteexternalresourcessothatwecanevaluateyourown

personalcontributions.

•  Donotreleaseyoursolutions(notevenafterendofsemester)•  Askifyouhaveanyquestions•  Ifyouarefeelingdesperate,pleasemail/call/talktous

–  Alwaysturninanyworkyou'vecompletedbeforethedeadline

•  Weusecheatingdetectiontools•  Youmustsignandreturnacopyofthecollaborationpolicy

beforewewillgradeyourwork:https://goo.gl/CBXKQK–  UploadsignedcollaborationpolicytoGradescope

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Latedaypolicy

•  Youmayturnineach*homeworkupto2dayslate•  Youhavefivefreelatedayspersemester

–  10%penaltyperdayafterfreelatedaysareused•  Wedon'tacceptwork3dayslate•  Seethesyllabusforadditionaldetails•  Gotextremecircumstances?Talktous

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10%quizzesandparticipation

•  Recitationparticipationcountstowardyourparticipationgrade•  Lecturehasin-classquizzes

–  Ifyouparticipateasynchronously,youmustcomplete"in-class"activitieswithin48hoursofclass

The key to your success in this course is your regular, synchronous engagement with course

activities, staff, and other students

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Summary

•  Softwareengineeringrequiresdecisions,judgment•  Gooddesignfollowsaprocess•  Youwillgetlotsofpracticein17-214!