state diagrams & file system

8/8/2019 State Diagrams & File System

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Terms and ConceptsTerms and Concepts


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AdvancedAdvanced StatesStates andand TransitionsTransitions HistoryHistory StatesStates -- AllowsAllows anan objectobject toto rememberremember whichwhich

substatesubstate waswas lastlast activeactive whenwhen thethe containingcontaining statestatewaswas exitedexited..

UponUpon rere--entryentry toto thethe containingcontaining state,state, thethe substatesubstate thatthatwaswas lastlast activeactive willwill bebe rere--enteredentered directlydirectly..


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History State ExampleHistory State Example


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History State RestrictionsHistory State Restrictions TransitionsTransitions maymay onlyonly enterenter aa historyhistory statestate fromfrom

outsideoutside thethe compositecomposite statestate

IndicatesIndicates thethe defaultdefault reenteredreentered statestate ifif thethecompositecomposite statestate hashas notnot yetyet beenbeen enteredentered

HistoryHistory statesstates maymay notnot havehave internalinternaltransitions,transitions, nestednested compartments,compartments, etcetc..


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AdvancedAdvanced StatesStates andand TransitionsTransitions

ConcurrentConcurrent SubstatesSubstates -- UsedUsed whenwhen twotwo orormoremore statestate diagramsdiagrams areare executingexecutingconcurrentlyconcurrently withinwithin aa singlesingle objectobject..

AllowsAllows anan objectobject toto bebe inin multiplemultiple statesstatessimultaneouslysimultaneously..

TheThe concurrentconcurrent statestate diagramsdiagrams withinwithin aacontainingcontaining statestate mustmust beginbegin andand endend executionexecution

simultaneouslysimultaneously..

IfIf oneone concurrentconcurrent statestate diagramdiagram finishesfinishes first,first, ititmustmust waitwait forfor thethe othersothers toto completecomplete beforebefore exitingexitingthethe containingcontaining statestate..


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Concurrent Composite StatesConcurrent Composite States

TheThe regionsregions inin aa concurrentconcurrent compositecomposite statestatenestednested statestate compartmentcompartment containcontain statestatediagramsdiagrams thatthat executeexecute inin parallelparallel..

OneOne statestate inin eacheach regionregion isis enteredentered whenwhen thetheconcurrentconcurrent compositecomposite statestate isis enteredentered..

OneOne statestate fromfrom eacheach regionregion isis alwaysalways amongamongthethe jointjoint concurrentconcurrent statesstates untiluntil thethe concurrentconcurrentcompositecomposite statestate isis exitedexited..

EventsEvents causecause transitionstransitions inin eacheach concurrentconcurrentregionregion toto occuroccur simultaneouslysimultaneously..


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Concurrent Composite State ExampleConcurrent Composite State Example


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Entering Concurrent Composite StatesEntering Concurrent Composite States

MakeMake aa transitiontransition toto thethe concurrentconcurrent compositecomposite statestateboundaryboundary

TheThe initialinitial statestate inin eacheach regionregion becomesbecomes thethe currentcurrent statestate MakeMake aa transitiontransition toto individualindividual statesstates inin differentdifferent

regionsregions MainMain transitiontransition goesgoes toto aa forkfork barbar

TransitionsTransitions toto individualindividual statestate comecome fromfrom thethe forkfork barbar AA regionregion withoutwithout aa statestate targetedtargeted byby aa transitiontransition beginsbegins

inin itsits initialinitial statestate


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Entering Selected Concurrent StatesEntering Selected Concurrent States


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Leaving Concurrent Composite StatesLeaving Concurrent Composite States

MakeMake aa transitiontransition fromfrom thethe concurrentconcurrent compositecompositestatestate boundaryboundary

ForFor aa nonnon--completioncompletion transition,transition, a

llall

concurrentconcurrent subsub--statesstates areare exitedexited immediatelyimmediately

ForFor aa completioncompletion transition,transition, thethe currentcurrent statestate mustmust bebeaa finalfinal statestate inin everyevery concurrentconcurrent regionregion

M

akeM

ake aa transitiontransition fromfrom oneone oror moremore concurrentconcurrentsubsub--statesstates

CoordinatedCoordinated transitionstransitions cancan gogo toto aa joinjoin barbar

AllAll otherother subsub--statesstates areare exitedexited immediatelyimmediately


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Leaving Selected Concurrent StatesLeaving Selected Concurrent States


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ConcurrentConcurrent

StateStateDiagramsDiagrams

Using OMTUsing OMT

NotationNotation


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State Diagram for a Phone LineState Diagram for a Phone Line


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Event TraceEvent Tracefor an ATMfor an ATM

TransactionTransaction


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State Diagrams ATM, Bank, and ConsortiumState Diagrams ATM, Bank, and Consortium


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File TypesFile Types


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FilesFiles

FileFile isis aa co

llectionco

llection ofof re

latedrelated recordsrecords inin whichwhich eacheachrecordrecord containscontains relatedrelated datadata fieldsfields..

FileFile isis composedcomposed ofof recordsrecords andand fieldsfields..

RecordRecord isis collectioncollection ofof relatedrelated datadata itemsitems..

FieldField isis aa namename givengiven toto eacheach datadata itemitem containedcontained ininaa recordrecord..

TypesTypes ofof FileFile::

1.1. MasterMaster FileFile

2.2. TransactionTransaction FileFile3.3. HistoryHistory FileFile

4.4. SortSort FileFile

5.5. BackupBackup FileFile


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Types Of FilesTypes Of Files1.1. MasterMaster FileFile:: ItIt includesincludes datadata ofof permanentpermanent naturenature..

EmployeeEmployee salarysalary file,inventoryfile,inventory filefile andand customercustomer filesfilesareare mastermaster filesfiles..

2.2. TransactionTransaction FileFile:: ItIt isis temporarytemporary filefile usedused totoupdateupdate mastermaster filefile..

3.3. HistoryHistory FileFile:: ThisThis filefile cancan bebe createdcreated forfor longlong--termtermstoragestorage..

4.4. ReportReport FileFile:: AA filefile ofof informationinformation onon auxiliaryauxiliarymagneticmagnetic tapetape oror diskdisk..

5.5. SortSort FileFile:: AA filefile havinghaving oneone oror moremore fieldsfields inin somesomesortedsorted orderorder..6.6. BackupBackup FileFile:: AA copycopy ofof filefile toto ensureensure thatthat datadata areare

notnotlostlost ifif thethe originaloriginal filefile isis lostlost oror damageddamaged..


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Master Fi

le

Master Fi

le

AA collectioncollection ofof recordsrecords pertainingpertaining toto oneone ofofthethe mainmain subjectssubjects ofof anan informationinformation system,system,suchsuch asas customers,customers, employees,employees, productsproducts andand

vendorsvendors.. MasterMaster filesfiles containcontain descriptivedescriptive data,data, suchsuch asas

namename andand address,address, asas wellwell asas summarysummaryinformation,information, suchsuch asas amountamount duedue andand yearyear--toto--

datedate salessales.. AA filefile thatthat isis relativelyrelatively permanentpermanent andand usuallyusually

updatedupdated periodicallyperiodically..


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Transaction FileTransaction File

AA collectioncollection ofof transactiontransaction recordsrecords..

TheThe datadata inin transactiontransaction filesfiles isis usedused totoupdateupdate thethe mastermaster files,files, whichwhich containcontain thethedatadata aboutabout thethe subjectssubjects ofof thetheorganizationorganization..

TransactionTransaction filesfiles alsoalso serveserve asas auditaudit trailstrailsandand historyhistory forfor thethe organizationorganization..


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Report File and Backup Fi

leReport Fi

le and Backup Fi

le

ReportReport FileFile AA filefile thatthat describesdescribes howhow aa reportreport isis printedprinted..

BackupBackup FileFile AA computercomputer filefile dedicateddedicated toto storingstoring andand

updatingupdating computercomputer backupsbackups..

TheThe branchbranch ofof engineeringengineering sciencescience thatthatstudiesstudies (with(with thethe aidaid of of computers)computers)computablecomputable processesprocesses andand structuresstructures..

ReportReport FileFile isis aa filefile maintainedmaintained inin computercomputer--readablereadable formform..


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Table Fi

leTab

le Fi

le

AA TABLETABLE filefile hashas aa simplesimple structurestructure.. ThereThereareare threethree kindskinds ofof recordsrecords::

COMMENTCOMMENT LINESLINES beginbegin withwith thethe charactercharacter '#''#'andand areare ignoredignored..

BLANKBLANKLINESLINES areare ignored,ignored, butbut couldcould bebe usedusedbyby aa particularparticular programprogram toto indicateindicate somesome

intendingintending groupinggrouping oror separationseparation ofof recordsrecords.. COORDINATECOORDINATE LINESLINES eacheach containcontain oneone setset ofof

pointpoint coordinatescoordinates..


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Files Management SystemFiles Management System ItIt isis thethe simplestsimplest typetype ofof programprogram usedused toto managemanage

thethe filesfiles.. TheThe softwaresoftware thatthat managesmanages thethe storage,storage, accessaccess to,to,

retrievalretrieval fromfrom andand useuse ofof flatflat filesfiles isis calledcalled FileFileManagementManagement SystemSystem (FMS)(FMS)..

AA flatflat filefile isis aa filefile thatthat hashas nono relationshiprelationship withwith anyany

otherother filefile..AdvantagesAdvantages::

LowLow purchasepurchase priceprice EaseEase ofof operationoperation andand maintenancemaintenance LowLow vulnerabilityvulnerability toto datadata errorserrors..

DisadvantagesDisadvantages:: FlatFlat filesfiles areare independentindependent andand areare notnot integratedintegrated.. TheThe samesame datadata areare oftenoften duplicatedduplicated inin multiplemultiple filesfiles.. ProgramsPrograms toto managemanage datadata inin multiplemultiple flatflat filesfiles atat thethe

damedame timetime areare difficultdifficult toto createcreate andand maintainmaintain..


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Database ProcessingDatabase Processing DatabaseDatabase isis collectioncollection ofof relatedrelated andand crosscross

referencedreferenced datadata designeddesigned andand createdcreated totominimizeminimize repetitionsrepetitions andand easeease manipulationmanipulationofof datadata..

HowHow datadata isis storedstored inin databasesdatabases:: TheThe datadata isis storedstored inin databasesdatabases inin oneone ofof

thethe threethree typestypes ofof datadata structuresstructures::1.1. FilesFiles

2.2. TablesTables3.3. ObjectsObjects


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DatabasesDatabasesAdvantagesAdvantages:: DataData redundancyredundancy reducedreduced DataData integrityintegrity improvedimproved DataData independenceindependence maintainedmaintained DataData securitysecurity improvedimproved

DataData consistencyconsistency maintainedmaintained MoreMore powerfulpowerful manipulationmanipulation ofof datadata allowedallowed EasierEasier datadata accessaccess andand useuse

DisadvantagesDisadvantages:: HighlyHighly complexcomplex andand requirerequire specializedspecialized programmersprogrammers.. ExpensiveExpensive inin termsterms ofof hardwarehardware andand softwaresoftware MassiveMassive destructiondestruction toto datadata cancan occuroccur ifif thethe securitysecurity collapsecollapse..


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Database ManagementDatabase Management

System(DBMS)System(DBMS) ItIt isis softwaresoftware thatthat managesmanages thethe creation,creation, storage,storage,

access,access, updating,updating, deletiondeletion andand useuse ofof databasedatabase.. AADBMSDBMS hashas thethe followingfollowing featuresfeatures::

1.1. CreatesCreates databasedatabase byby usingusing informationinformation providedprovided bybythethe designersdesigners2.2. ItIt providesprovides programsprograms toto access,access, modifymodify andand

manipulatemanipulate datadata inin databasedatabase..3.3. GenerationGeneration ofof reportreport..

4.4. SecuritySecurity forfor databasedatabase5.5. ReportsReports toto managementmanagement thatthat whowho accessedaccessed

databasedatabase andand whatwhat activityactivity waswas performedperformed..6.6. AutomaticAutomatic backupbackup forfor datadata..


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Kinds of DBMSKinds of DBMS

1.1. SingleSingle--useruser systemsystem withwith singlesingle applicationapplicationdatabasedatabase

2.2. SingleSingle--useruser systemsystem withwith multiplemultiple applicationapplicationdatabasedatabase

3.3. MultipleMultiple--useruser systemsystem withwith singlesingle applicationapplicationdatabasedatabase

4.4. MultipleMultiple--useruser systemsystem withwith multiplemultipleapplicationapplication databasedatabase..


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Database ModelsDatabase Models 44 typestypes ofof databasedatabase modelsmodels::

1.1. HierarchicalHierarchical ModelModel2.2. NetworkNetwork ModelModel3.3. RelationalRelational ModelModel

4.4. ObjectObject--orientedoriented ModelModel


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2. NetworkM

odel

2. NetworkM

odel

SimilarSimilar toto HierarchicalHierarchical modelmodelexceptexcept thatthat eacheach recordrecord cancanhavehave moremore thanthan oneone parentparentthusthus creatingcreating manymany toto manymany

relationshiprelationship inin thethe recordsrecords.. MainMain advantageadvantage ofof networknetwork

databasedatabase isis thethe abilityability totohandlehandle sophisticatedsophisticatedrelationshiprelationship amongamong variousvariousrecordsrecords.. thereforetherefore moremore thanthanoneone pathpath cancan leadlead toto desireddesiredlevellevel..

DataData accessaccess isis fastfast..


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3. RelationalModel3. RelationalModel

ComposedComposed ofof manymany tablestables inin whichwhich datadata areare storedstored.. TablesTables havehave uniqueunique rowsrows andand thethe cellcell hashas singlesingle

valuevalue.. AA databasedatabase managementmanagement systemsystem thatthat allowsallows thethe

datadata toto readilyreadily created,created, maintainedmaintained andand manipulatedmanipulatedandand retrievedretrieved fromfrom relationalrelational databasedatabase isis calledcalledRelationalRelational DatabaseDatabase ManagementManagement SystemSystem

DatabaseDatabase QueryQuery LanguageLanguage isis helpfulhelpful tooltool thatthat actsacts asasanan interfaceinterface betweenbetween usersusers andand RDBMSRDBMS..

22 basicbasic queryquery stylesstyles inin re

lationa

lre

lationa

ldatabasedatabase::1.1. QueryQuery byby exampleexample

2.2. StructuredStructured QueryQuery LanguageLanguage

HighHigh costcost


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4. Object4. Object--Oriented ModelOriented Model ItIt usesuses objectsobjects andand messagesmessages toto

accommodateaccommodate newnew typestypes ofof datadata andandprovideprovide forfor advanceadvance datadata handlinghandling..

AA systemsystem thatthat allowsallows objectsobjects toto create,create,manipulate,manipulate, maintainedmaintained andand retrievedretrievedfromfrom anan objectobject--orientedoriented databasedatabase isiscalledcalled Object Object--orientedoriented databasedatabasemanagementmanagement systemsystem (OODBMS)(OODBMS)..

ItIt isis usedused forfor applicationsapplications whichwhich areareusingusing complexcomplex datadata..

state diagrams & file system

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