Download - Clase 1 Ingenieria de Software
Goals of this courseIntroduce industrial-strength softwaredevelopment: formal processes/artifacts for planning, specifying, designing,
implementing, and verifying Individual and team-based development life-cycle issues and “umbrella” activities
Introduce key foundations underlying theseactivitiesE.g., requirements engineeringE.g., software modelingE.g., assurance
How “different” is this course?Quite!Not a “programming course”Exercises aim to facilitate problem understanding, solutions, tradeoffs, and sensitivity to challenges that affect industrial software developmentWritten and oral communication skills will be exercised, improved, and assessedThe work is individual and will be assessed
What is SoftwareEngineering ???
The study of systematic and effectiveprocesses and technologies for supportingsoftware development and maintenanceactivitiesImprove qualityReduce costs
Historical Perspective1940s: computers invented
1950s: assembly language, Fortran
1960s: COBOL, ALGOL, PL/1, operating systems
1969: First conference on Software Eng
1970s: multi-user systems, databases, structuredprogramming
Historical Perspective (cont.)1980s: networking, personal computing,embedded systems, parallel architectures1990s: information superhighway, distributedsystems, OO in widespread use.2000s: virtual reality, voice recognition, videoconferencing, global computing, pervasivecomputing...2010s: EMRs, autonomous vehicles, new securityawareness, ...2015s: ubiquitous computing
Why is software so expensive?Hardware has made great advances
But, software has made great advances ...
We do the least understood tasks in software.When task is simple & understood, encode it in hardwareWhy?
Demand more and more of softwareConsider your cell phone
Size of programs continues to grow
Trivial: 1 month, 1 programmer, 500 LOC, Intro programming assignments
Very small: 4 months, 1 programmer, 2000 LOC Course project
Small: 2 years, 3 programmers, 50K LOC Nuclear power plant, pace maker
Medium: 3 years, 10s of programmers, 100K LOC Optimizing compiler
New ScaleUltra-Large Scale SW-Intensive Systems
Healthcare Infrastructure
© 2007 Carnegie Mellon UniversityUltra-Large-Scale SystemsLinda Northrop, ICSE 2007
New ScaleIntelligent Transportation and Vehicle Systems
Ultra-Large-Scale Systems Linda Northrop, ICSE 2007© 2007 Carnegie Mellon University
The ULS EcosystemKey elements:Computing devicesBusiness and organizational policiesEnvironment (including people)
Forces:Competition for resourcesUnexpected environmental changesDecentralized controlDemand for assurance
Context: ‘’Sufficient’’ System HealthHigh-level Objective:How to design a safe adaptive system with incomplete information and
evolving environmental conditions
Execution environmentHow to model environmentHow to effectively monitor changing conditionsAdaptive monitoring
Decision-making for dynamic adaptationDecentralized controlAssurance guarantees (functional and non-functional constraints)
Adaptation mechanisms:Application levelMiddleware level
What’s the problem?Software cannot be built fast enough tokeep up withH/W advancesRising expectationsFeature explosion
Increasing need for high reliability software
What’s the problem?Software is difficult to maintain “aging software”
Difficult to estimate software costs and schedulesToo many projects failArianne MissileDenver Airport Baggage SystemTherac
Why is software engineering needed?
To predict time, effort, and costTo improve software qualityTo improve maintainabilityTo meet increasing demandsTo lower software costsTo successfully build large, complex softwaresystems
To facilitate group effort in developing software
Show’s model of engineeringevolution [Shaw-IEEE-Computer90]
Production
CommercialCraft
Science
Engineering
Characteristics: CraftVirtuosos and talented amateursIntuition and brute forceHaphazard progressCasual transmission of knowledgeExtravagant use of available materialsManufacture for use rather than sale
Examples: woodworking, artists, hobbies
Characteristics: Commercial productionSkilled craftsEstablished procedurePragmatic refinementTraining in specific domain (e.g., mechanics--automotive technicians, structures-- constructionworker, electricians)Economic concern for cost and supply of materialsManufacture for sale
Examples: automotive parts, chip manufacturing
Characteristics: Professional engineering
Educated professionalsAnalysis and theoryProgress relies on scienceEducated professional classNew applications enabled through analysisMarket segmentation by product variety
Examples: civil engineering (bridges, buildings), automotiveengineers (electronics, mechanical engineering)
Evolution of Civil Engineering
ProductionCommercial
Craft
ScienceEngineering
1st century:Romans
1750: MateriaL Properties 1850: Bridg Analysis
1700: Statics, strengthof materials
Civil EngineeringBasis in theory.Actually two theories:oStatics: composition of forces.oMaterial strength: bending of a beam.Theories preceded real CE by 150 years!
Underlying science emerged 1700 yearsafter commercial production evolved!
Software Engineering Evolution(circa 1990)
Science: algorithms, logic, databases, languages
Production
Craft
Commercial
Engineering
1980’s: DevelopmentMethodologies
1965-70: algorithms1980-85: ADTs
Isolated Examples (5ESS, Shuttle)
Science
Two “pillars” of SE educationBasis in:production processes and process frameworksrigorous theories addressing design problems thatattend to the various phases of these processes
This course:organized around first pillarstructured so that process issues will motivateintroduction of theoretical content
Software Engineering Phases
Definition: What?
Development: How?
Maintenance: Managing change
Umbrella Activities: Throughout lifecycle
DefinitionRequirements definition and analysisDeveloper must understand
oApplication domain
oRequired functionality
oRequired performance
oUser interface
Definition (cont.)
Project planningAllocate resourcesEstimate costsDefine work tasksDefine schedule
System analysisAllocate system resources to
o Hardwareo Softwareo Users
DevelopmentSoftware designUser interface designHigh-level designoDefine modular componentsoDefine major data structuresDetailed designoDefine algorithms and procedural detail
Development (cont.)
CodingDevelop codefor each module
Unit testing
IntegrationCombine modulesSystem testing
MaintenanceCorrection - Fix software defectsAdaptation - Accommodate changesNew hardwareNew company policiesPrevention - make more maintainableEnhancement - Add functionality
Umbrella Activities
Reviews - assure quality
Documentation - improvemaintainability
Version control - track changes
Configuration management - integrityof collection of components