Software taxonomies Patterns, styles, tactics,

Software ArchitectureS

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Software taxonomiesPatterns, styles, tactics,...

Jose E. Labra GayoCourse 2020/2021


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Building & MaintenanceConfiguration management

Modularity Decomposition at building time

Runtime Components and connectors

IntegrationAllocation

Packaging, distribution, deploymentBusiness and enterprise environment


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Software construction & maintenance

Jose E. Labra GayoCourse 2018/2019


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edo Software construction & maintenance

Configuration management


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edo Software: product or service

Software as a Product (SaaP): Software deliverable

Commercial model: software is sold to clientsSoftware distributed or downloaded

Example: Microsoft OfficeSoftware as a Service (SaaS):

Software deployedCommercial model: clients subscribe to itSoftware usually available at some URL

Example: Google docs


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edo Software configuration management

Managing the evolution of softwareManages all aspects of software constructionEspecially, how software evolves and changes

Aspects:Identifying baselines and configuration items

Baseline: A work product subject to managementIt contains configuration items: documents, code files, etc...

Configuration control & auditingVersion control systems

Building management and automationTeamworkDefect and issues tracking


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edo Software construction

Overview of methodologiesTraditional, iterative, agile

Construction toolsLanguages, tools, etc.


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Development by needCodification without following the architectureThrow-away softwareBudget constraints


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Software development life cycle (SDLC)Waterfall model identified as antipattern in 1970s

Waterfall

Requirements

Design

Implementation

Verification

Maintenance


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Requirements

Analysis

Design

ObjectDesign

UnitTesting

IntegrationTesting

SystemTesting

AceptanceTesting

Time

DetailLevel

Low

High Implementation

Project Definition

Project Test and

Integration


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edo Big Design Up Front

Anti-pattern of traditional modelsToo much documentation that nobody readsDocumentation different from developed system

Architecture degradationSoftware implemented but unused


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edo Iterative Models

Based on PrototypesRisk assessment after each iteration

InitialPlanning

Planning

Requirements Analysis & Design

Implementation

Deployment

TestingEvaluation


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edo Agile methodologies

Lots of variantsRAD (www.dsdm.org, 95)SCRUM (Sutherland & Schwaber, 95)XP - eXtreme Programming (Beck, 99)Feature driven development (DeLuca, 99)Adaptive software development (Highsmith, 00)Lean Development (Poppendieck, 03)Crystal Clear (Cockburn, 04)Agile Unified Process (Ambler, 05). . .


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edo Agile methods

Agile Manifesto (www.agilemanifesto.org)

Individuals and interactions

overProcesses and

Tools

Working Software

ComprehensiveDocumentation

over

CustomerCollaboration

over ContractNegotiation

Respondingto change

over Following aPlan


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edo Agile methods

FeedbackChanges of code are OK during development

Minimize riskSoftware in short intervalsIterations of daysEach iteration takes all the development cycle


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edo Some agile principles (XP)

1. Adapt to change2. Testing3. Pair programming4. Refactoring5. Simple design6. Collective code ownership7. Continuous integration8. On-site customer9. Small releases10.Sustainable pace11.Coding standards


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edo Adopt change

After each iteration, update plansRequirements through user stories

Short descriptions (size of a card)Goals ordered by usnig according to priorityRisk and resources estimated by developers

User stories = acceptance testingWelcome changing requirements

Original plan

Current plan


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Write a test before codingInitially, code will failGoal: pass the testResult:

Automated set of testsEasier refactoring


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edo Different types of testing

Unit testingCheck each unit separately

Integration testingSmoke testing

Acceptance testingCheck with user stories

Performance/capacity testing:Load testing

Regression testingCheck that new changes don’t introduce new bugs, or

regressions


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edo Types of testing

Functional Acceptance Testing

ShowcasesUsability testing

Exploratory testing

Nonfunctional Acceptance testing

(capacity, security,…)

Unit testingIntegration testing

System testing

Automated Manual

Automated Manual/ Automated

Supp

ort p

rogr

amm

ing C

ritique projectBusiness facing

Technology facing

Source: Continuous delivery, J Humble, D. Farley, 2010


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edo Acceptance testing

Behavior-driven development (BDD)Tests come from user storiesThey can be written collaboratively with the client

Tools: Cucumber, JBehave, Specs2,...Tests act as contractsCan also be used to measure progress

Feature: Buscar cursosPara mejorar el uso de los cursosLos estudiantes deberían ser capaces de buscar cursos

Scenario: Búsqueda por asuntoGiven hay 240 cursos que no tienen el asunto “Biología”And hay 2 cursos A001, B205 que tienen el asunto “Biología" When Yo busco el asunto “Biología"Then Yo debería ver los cursos:

| Código || A001 || B205 |


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edo Testing: FIRST Principles

F - FastExecution of (subsets of) tests must be quick

I - Independent: No tests depend on others

R - Repeatable: If tests are run N times, the result is the same

S - Self-checkingTest can automatically detect if passed

T - TimelyTests are written at the same time (or before) code


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edo Test doubles

Dummy objects: Objects that are passed but not used

Fake objects: Contain a partial implementation. Stubs: contain specific answers to some requestsSpies: stubs that record information for

debuggingMocks: mimic the behavior of the real object

Mocks may contain assertions about the order/number of times methods are called

Fixtures: Tools that support testsTesting databases, some files, etc.


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edo Environments

A staging environment is also used

Developmentenvironment

TestingEnvironments

ProductionEnvironment

TestingServer

IntegrationServer

VersionControl

ProductionServer

Server farm


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edo Pair programming & Code reviews

2 software engineers work togetherDriver manages keyboard and creates

implementationObserver identifies failures and gives ideas

Roles are exchanged after some timePull requests: Before accepting changes, code

can be reviewed


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edo Simplicity

Favor Simple designReaction to Big Design Up FrontObtain the simpler design that works

Automated documentationJavaDoc and similar tools


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Improve design without changing functionalitySimplify code (eliminate redundant code)Search new opportunities for abstraction

Regression testingBased on the test-suite


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edo Collective ownership of code

Code belongs to the project, not to some engineerEngineers must be able to browse and modify any

part of the codeEven if they didn't wrote itAvoid code fragments that only one person can

modify


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edo Continuous Integration

Frequently integrating one's new or changed code with the existing code repositoryRunning all unit and integration testsMerge all developer working copies

GoalsHelp Test Driven DevelopmentMaintain all programmers code up to dateAvoid integration hell


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Continuous IntegrationBest practices:

Maintain code repositoryAutomate the buildMake the build self testingEveryone commits to the baselineEvery commit should be builtKeep the build fastTest in a clone of the production environmentMake it easy to get the latest deliverablesEveryone can see the results of the latest buildAutomate deployment


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Continuous integration toolsHudson, Jenkins, Travis, Bamboo

ContinuousIntegration

WebInterface

Reports

checkout/commit

Central Coderepository

DevelopmentTeam


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edo On-place customer

Customer available to clarify user stories and help taking critical business decisions

AdvantagesDevelopers don't do guessesDevelopers don't have to wait for decisionsImproves communication


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edo Continous delivery

Small releasesSmall enough while offering value to the user

Obtain feedback soon from clientDelivery models

Try to release something every night/week...Continuous and automated delivery


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edo Sustainable pace

Avoid extra-work loads40h/week = 40h/week

Tired programmers write bad codeIt will slow the development at long time


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edo Clean code & code conventions

Facilitate code refactoring by other peopleUse good practices

Code styles and guidelinesAvoid code smells

software craftmanship manifestClean Code (Robert C. Martin)

Fuente: Clean Code. Robert Martin


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edo Some agile methods

VariantsScrum

Project/people managementDivide work in sprints

15' daily meetingsProduct Backlog

KanbanLean model

Just in Time DevelopmentLimit workloads


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edo Configuration Management

Different software versionsNew or different functionalitiesIssues and bugs managementNew execution environments

Configuration managementManage software evolutionSystem changes = team activitiesImply cost and effort


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edo Version control

Systems that manage different code versionsBe able to Access all the system versions

Easy to rollbackDifferences between versions

Collaborative developmentBranch managementMetadata

Author of a version, update date, who to blame, etc.


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edo Baseline

Baseline: Software which is the object of configuration management

Version1.0

Windows

Version1.5

Sun

Version1.5

Linux

Version2.0

Windows

Version2.5 desktop

Linux

Version2.5 desktop

Servidor


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edo Releases and versions

Version: instance of a system which has a different functionality to other instances

Release (deliverable): instance of a system which is distributed to external people outside to development team.It can be seen as a final product at some point


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Pre-alphaBefore testing

AlphaDuring testing

Beta (or prototype)Testing made by some users

Beta-tester: user that does the testingRelease-candidate

Beta version that could become final product


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Using some attributesDate, creator, language, client, state,...

Recognizable Names Ganimede, Galileo, Helios, Indigo, Juno,...Precise Pangolin, Quantal Quetzal,...

Semantic Versioning (http://semver.org)MAJOR.MINOR.PATCH (2.3.5)

MAJOR: changes incompatible with previous versionsMINOR: new functionality compatible with previous versionsPATCH: Bugfix compatible with previous versions

Version 0 (inestable)Pre-releases (names added at the end): 2.3.5-alpha


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A release implies functionality changesPlanning

Publishing a release has costsUsually, current users don't want new releasesExternal factors:

Marketing, clients, hardware, ...Agile model: frequent releases

Continuous integration minimizes risk


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A release is more than just softwareConfiguration filesSome needed data filesInstallation programsDocumentationPublicity and packaging


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edo Continuous delivery

Continuous deliveryFrequent releases to obtain feedback as soon as possible

TDD & continuous integrationDeployment pipeline

Advantages: Embrace changeMinimize integration risks

Wabi-sabi philosophyAccept imperfectionSoftware that is not finnished: Good enough


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edo DevOps

Merge development and operationsCultural change where the same team participates in:

Code: Development and code review, continuous integrationBuild: Version control, building and integrationTestPackage: Artifact managementRelease: version automationConfiguration and managementMonitorization: performance, user experience


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edo Construction languages

Configuration languages Resource definitions (Json, XML, Turtle)

Examples: .travis.yml, package.json, pom.xmlScripting languages

Shell/batch scriptsProgramming languages

Examples: Java, Javascript,...Visual languages

Examples: scratch, blender, ...Formal

Examples: B-trees, Z language, OCL, ...


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Program

Coding aspectsNaming conventions

Important for other programmers, maintainers...Classes, types, variables, named constants, ...Error handlingSource code organization

Packages, folders, ...Dependencies

Libraries importedCode documentation

Javadocs, jsdoc...

Programmer

Program

Computer

Other programmers& maintainers


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Unit testingIntegration testingLoad testingRegression testing. . .Best practice:

Separate testing code and dependencies from production code


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ParameterizationAdd parameters

Common error: magical numbers in codeConfiguration/resource files

Conditional compilationEncapsulation

Separate interface from implementationCommon error: internal parts public in libraries

PackagingCommon error: manual tasks for packaging

DocumentationAPI documentation


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Selection of reusable unitsExternally developed components (COTS, FOSS)

Handling dependencies<See later>

Handling updatesWhat happens when other libraries are updated?

Legal issuesCan I really use that library?

For commercial software?Be careful with GNU libraries

Is the library well maintained?


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edo Construction tools

Text editorsvi, emacs, Visual Studio Code, Sublime,....

Integrated Development Environments (IDEs)Examples: IntelliJ, Eclipse

Graphical User Interface (GUI) buildersAndroid Studio UI Editor, QtEditor,...

Quality assurance (QA) toolsTest, analysis, ...<See next slide>


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TestsxUnit, test frameworks (mocha)Assertion languages (chai)Test coverage tools

AssertionsPre-conditions asserted on methods

Inspections & code reviewsPull requests with code reviews

Code Analysis tools<See next slide>


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Static vs dynamic code analysisWithout running the code (or at runtime)Examples: PMD, SonarCube,... (Codacy)

DebuggersInteractive vs static, Tracers & logging

ProfilersInformation about resource usage

Memory, CPU, method calls, etc.Test coverage tools

Report which lines of code have been run during testsProgram slicing

Program fragment (slice) that has been run Examples: CodeSurfer, Indus-kaveri,...


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DefinitionsRepository: where changes are

storedBaseline: Initial versionDelta: changes from one version

to otherTrunk (master): Main branch in a

systemBranch: deviation from main

branchTag: Marks a line of versions

1

Baseline

4

Trunk

2

3Branchs

5

6

9

7

T1

T2

8

10

Tags merge


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DefinitionsCheckout: Working Local copy from a

given branchCommit: Introduce current changes in

the control version system.Merge: Combine two sets of changesBranching styles: by feature, by team,

by version

1

Baseline

4

Trunk

2

3Branchs

5

6

9

7

T1

T2

8

10

Tagsmerge


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2 typesCentralized

Centralized repository for all the codeCentralized administrationCVS, Subversion, ...

DistributedEach user has its own repositoryGit, Mercurial


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edo Git

Designed by Linus Torvalds (Linux), 2005Goals:

Applications with large number of source code filesEfficiency

Distributed workEach development has its own repository

Local copy of all the changes historyIt is possible to do commits even without internet connection

Support for non-lineal development (branching)

More information:http://rogerdudler.github.com/git-guide/


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3 local components:Local working directoryIndex (stage area). Also called cacheProject history: Stores versions or commitsHEAD (most recent version)

ProjectHistory

Commits

commitadd

rm

HEADLocal

workingdirectory

Indexstagearea


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Local workingdirectory

HistoryCommits

Indexstagearea

Remoterepositoryorigin

push

clonefetchpull

commitadd

rm

Local Machine

HEAD

Connect with remote repositoriesorigin = initial


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Git facilitates branch managementmaster = initial branch

Operations:Create branches (branch)Change branch (checkout)Combine (merge)Tag branches (tag)

1

Baseline

4

Trunk

2

3Branchs

5

6

9

7

T1

T2

8

10

Tagsmerge


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edo Branching patterns

Git-flowDevelop branch as mainline

Github-flowEverything in master is deployableNo hotfix branchPromotes pull-requests

Trunk-based developmentEverything in trunk (master)Short-lived feature branching

masterdevelop hotfix-1feature-1feature-2

0.1

1.0

0.2

tags

Branches

https://martinfowler.com/articles/branching-patterns.html

https://martinfowler.com/articles/branching-patterns.html


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edo Dependency management

Library: Collection of functionalities used by the system that is being developedSystem depends on that library

Library can depend on other librariesLibrary can evolve

Incompatible versions appearDependency graph

Mozilla Firefox dependency graphSource: The purely functional deployment model. E. Dolstra (PhdThesis, 2006)


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edo Dependency graph

Graph G = (V,E) whereV = Vertex (components/packages)E = Edges (u,v) that indicate that u depends on v

CCD metric (cumulative component dependency)

Sum of every component dependencyEach component depends on itself

A

B C

D E G

In the example:CCD=7+3+4+1+1+1+1=18

F


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edo Cyclic dependencies problem

The dependency graph should not have cyclesAdding a cycle can damage CCD

Example:

CCD = 7+7+7+1+7+1+1=31

A

B C

D E GF


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edo Dependency management

Different modelsLocal installation: libraries are installed for all the system

Example: Ruby GemsEmbed external libraries in the system (version control)

Ensures a correct versionExternal link

External repository that contains the librariesDepends on Internet and on library evolution


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edo Build automation

Tools that automate building and deploymentOrganize different tasks

Compile, package, install, deploy, etc.Dependencies between tasksMust check:

Run all prerequisitesRun them once

Initialize

Prepare Testdata

CompileSource

code

CompileTestcode

Runtests


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Automate building tasksSome quality attributes:

Correctness: Avoid mistakes (minimize "bad builds")Eliminate repetitive and redundant tasks

Simplicity: Handle complexityAutomation & releasability

Have history of builds and releasesContinuous integration

CostSave time & money


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On-demandA user running a script at the command line

ScheduledAutomatically run at certain hoursContinuous integration serverExample: nightly builds

TriggeredAt every commit to a version control systemContinuous integration server linked to version

control system


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edo Build Automation Tools

Makefile (C world)Ant (Java)Maven (Java)SBT (Scala, JVM languages)Gradle (Groovy, JVM languages)rake (Ruby)npm, grunt, gulp (Javascript)etc.


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make: Included in UnixProduct orientedDeclarative language based on rules

When the Project is complex, configuration files can be difficult to manage/debug

Several versions: BSD, GNU, MicrosoftVery popular in C, C++, etc.


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ant: Java PlatformTask orientedXML syntax (build.xml)


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maven: Java PlatformConvention over configurationManage project lifecycleDependency managementXML syntax (pom.xml)


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Embedded languagesDomain specific languages embedded in higher level

onesGreat versatilityExamples: gradle (Groovy)sbt (Scala)rake (Ruby)Buildr (Ruby)gulp (Javascript)…


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Pants (Foursquare, twitter)https://pantsbuild.github.io/

Bazel (Google)http://bazel.io/

Buck (Facebook)https://buckbuild.com/


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edo Maven

Build automation toolDescribes how software is builtDescribes software dependenciesPrinciple: Convention over configuration

Jason van ZylCreator of Maven


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Typical development phases:clean, compile, build, test, package, install, deploy

Module identification3 coordinates: Group, Artifact, VersionDependencies between modules

Configuration: XML file (Project Object Model)pom.xml


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Artifact repositoriesStore different types of artifacts

JAR, EAR, WAR, ZIP, plugins, etc.Every interaction is made through the repository

No relative pathsShare modules between development teams

Local ArtifactRepository

RemoteArtifact

Repository

<user>/.m2/repository Maven Central


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Public repository of projectsOver 1 mill GAV≈ 3000 new projects each month (GA)≈ 30000 new versions each month(GAV)*

http://search.maven.org/

* Source: http://takari.github.io/javaone2015/still-rocking-it-maven.html

Other repositories:https://bintray.com/


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XML syntaxDescribes a project

Name and versionArtifact type (jar, pom, ...)Source code localizationsDependenciesPluginsProfiles

Alternative build configurationsInheritance structureReference: https://maven.apache.org/pom.html


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Inheritance structureSuper POM

Maven's default POMAll POMs extend the Super POM unless explicitly said

parentDeclares the parent POMDependencies and properties are combined


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Project identificationGAV (Group, Artifact, Version)

Group: grouping identifierArtifact: Project nameVersion: Format {Major}.{Minor}.{Maintenance}

It is possible to add "-SNAPSHOT" (in development)<project xmlns="http://maven.apache.org/POM/4.0.0"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0

http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>es.uniovi.asw</groupId><artifactId>censusesN</artifactId><version>0.0.1</version><name>censusesN</name>...


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Folder structureMaven uses a conventional structure

src/mainsrc/main/javasrc/main/webappsrc/main/resourcessrc/test/src/test/javasrc/test/resources. . .

Output directory: target


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edo Maven Build life cycle

3 built-in lifecyclesdefault

Project deploymentclean

Project cleaningsite

Project's site documentationEach life cycle has some specific phases


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Clean compiled code and other stuff3 phases

pre-cleancleanpost-clean


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Compilation, testing and deployingSome phases validate

initializegenerate-sourcesgenerate-resourcescompiletest-compiletestpackageintegration-testverifyinstalldeploy


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Generates Project's site documentationPhases

pre-sitesitepost-sitesite-deploy


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Automatic dependency managementGAV identificationScopescompile testprovide

Typejar, pom, war,...

...<dependency><groupId>commons-cli</groupId><artifactId>commons-cli</artifactId><version>1.3</version></dependency>...


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Automatic dependency managementDependencies are downloadedStored in a local repositoryWe can create intermediate repositories (proxies)

Examples: common artifacts for some companyTransitivity

A depends on B B depends on C⇒ If a system depends on A

Both B and C are downloaded


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Big projects can be decomposed in subprojectsEach Project creates one artifact

Contains its own pom.xmlParent Project groups modules

<project>...<packaging>pom</packaging><modules>

<module>extract</module><module>game</module>

</modules></project>


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Maven architecture based on plugins2 types of plugins

buildreporting

List of plugins: https://maven.apache.org/plugins/index.html


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Other phases and pluginsarchetype:generate - Generates Project archetypeeclipse:eclipse - Generates eclipse projectsite - Generates Project web sitesite:run - Generates Project web site and starts serverjavadoc:javadoc - Generates documentationcobertura:cobertura - Reports code executed during testscheckstyle:checkstyle - Check coding stylespring-boot:run - Run a spring application


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edo npm

Node.js package managerInitially create by Isaac Schlueter

Later became Npm inc.Default package manager for NodeJs

Manages dependenciesAllows scripts for common tasks

Software registryPublic or paid packages

Configuration file: package.json


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Configuration file: package.jsonnpm init creates a simple skeleton

Fields: {"name": "...mandatory...","version": "...mandatory...","description": "...optional...","keywords": "...","repository": {... },"author": "...","license": "...","bugs": {...},"homepage": "http://. . .","main": "index.js","devDependencies": { ... },"dependencies": { ... }"scripts": { "test": " ... " },"bin": {...},

}

Note: Yeoman provides fully featured scaffolding


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Repository: http://npmjs.orgInstalling packages:

2 options:Localnpm install <packageName> --save (--save-dev)

Globalnpm install -g <packageName>

http://npmjs.org/


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Dependency managementLocal packages are cached at node_modules folderAccess to modules through: require('...')

Global packages (installed with --global option)Cached at: ~/.npm folder

Scoped packages marked by @


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Npm contains lots of commandsstart ≈ node server.jstest ≈ node server.jsls lists installed packages...

Custom scripts: run-script <name>

More complex tasks in NodeJsGulp, Grunt

https://docs.npmjs.com/cli-documentation/

https://docs.npmjs.com/cli-documentation/

Documents

Software taxonomies Patterns, styles, tactics,