Integrative Programming languaege Module.pdf

Integrative Programming Module PDF FOR DEGREE PROGRM

1. IntegrativeProgramming
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CHAPTER1
IntroductiontoIntegrativeProgramming&Technologies
CourseLearningOutcome:
Attheendofthesemester,thestudentswillbeableto:
1.DiscusstheIntroductiontoIntegrativeProgrammingandTechnologies;
2.Explainintegrativetechnologiesormethodsusedinapplicationintegration;and
3.Evaluatethedifferenttypesofmiddlewareandhowthemiddlewaresolvesproblemof
heterogeneity.
Definition:
Integrationofsoftwarereferstotechniquesforcombiningexistingsoftware
componentstoformacompletesystem.
However,thesoftwareintegrationincludesatleastoneexistingsoftwaresystem,
developedinthepastwithnoplanforitssymmetricintegrationwithanother
componentinthefuture.
Integrativeprogrammingdealswithanintegrationapproachesandtechniquesthat
connectdifferentcomponentsofITinfrastructure-
People,
Applications,
Platformsand
Databasestoenableasecure,intraandinterapplicationcollaboration.
Integrativesolutionsenableanorganizationtointegratebusinessprocessesinternallyand
externallywithbusinesspartnerstocreatedynamicenvironmentsthatsupportscurrent
andevolvingbusinessrequirements,therebycreatingaglobalorganization.
Applicationintegrationassistsinunlimitedsharingofdataandbusinessprocesses
amonganyconnectedapplicationsordatasourcesinwithoutmakingmajorchanges
totheapplicationsordatastructures.
Integrationistheprocessofconnectingmultiple,independentlydevelopedapplications
usingincompatibletechnologiesintoasingleorganizationwidesystemwithinformation
flowingseamlesslyamongtheintegratedsystemsorcomponents.

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Mostoftheapplicationsthatruninorganizations’hardlyliveinisolation.
Whethertheregistrarapplicationmustinterfacewiththefinanceapplication,
thehumanresourcemanagementapplicationmustconnecttoeachother,it
seemslikeanyapplicationcanbemadebetterbyintegratingitwithother
applications.
Integrationofmultiple,independentlydeveloped,managedandmaintainedapplications
componentsthatmaynormallyuseincompatibletechnologiesandheterogeneous
platforms”
Enablestransmissionofinformationbetweenapplications,
Automatesflowofdatabetweenapplicationsthatmakeupthebusinessprocessflow.
Integrationistheprocessofcombiningseparateapplicationsintocooperating
collectionsofapplication.
Overviewofintersystemcommunication
Inter-systemcommunicationisthecommunicationbetweenasetofheterogeneous
systemsthatareintegratedtogether.
Theseintegratedsystemswhichputtogethermanyheterogeneoussetof
subsystemsandtheproducedobjectsareextremelydifferent,yetshould
contributetothesameprocess.
Softwareintegrationincludesoneormoreofthefollowing.
1.Systemintegration
Giventwoormoresystems,subsystemsorcomponents,eachofwhichfunction
properly(satisfyingtheirrequirementwithintheirenvironment).
Theproblemistointegratethemintoonelargersystemsatisfyingthecombined
requirementswithinthenewlyformedenvironment.
2.Functionalintegrationortechnologyintegration
Givenasoftwaresystem,thismayhavebeenfunctioningproperlyinthefieldfora
significantperiod.
Theproblemistointegrateanewfunctionoranewtechnologywithinthesystem.
Theintegratedsystemshouldprovidethenewfunctionalityorusethenew
technology,whilepreservingtheoriginalsystemfunctionality.

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3.Incrementalengineering
Asoftwaresystemcanbedevelopedanddeliveredusingavailabletechnologiesand
withlessfunctionalitythanitisintendedtofinallyprovide.
Newtechnologiesandormorefunctionsthencanbeintegratedwithinthesystem.
Theproblemistodesignthesystemwithsuchfutureintegrationinmind.
4.Modification
Sometimesanexistingandproperlyfunctioningsoftwaresystemmustbe
decomposedandintegratedtocarryoutmodification.
Theneedforintegration
Mostoforganizationsconsistofmorethanonedepartment,runningdepartment
specificapplicationsandthoseapplicationsinteractwitheachothertoachievethe
overallobjectiveoftheorganizations.
Informationsystemschangeovertimebygrowingintheirsize,incorporating
functionalityoftheexistingstandalonesystems.
Applicationsoriginallyintendedtooperateseparately,lateronarerequiredto
interoperatewithothers.
Someofthereasonsforintegrationarethefollowing;
•Technologychangeaffectsalllayers;legacydoesnotgoawaysoeasily.
•Thearchitectureoftheorganizationinformationsystemdependsonconstraints
relatedtothetechnologybutalsototheorganization.
•Withinanenterprise,eachdepartmentmayhaveitsownITinfrastructure,
systemsanddatabaseswhicharemaintainedindependently.
Integratingthemmaybringadditionalvaluetothecompany.
•IntegrationassistsinformationofZeroLatencyorganization-whenall
functionswithintheorganizationworkwiththesameup-to-dateinformation,
latencybetweenapplicationsiseliminated/reduced.
•Updatingandintegratingofapplicationsispossiblewheneverrequired.New
applicationscanbecreatedbyintegratingrealtimedatafromdifferentpartsof
theenterprise

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Integrationmodels
Integrationmodeldefineshowapplicationswillbeintegratedbydefiningthenature
ofandmechanismsforintegration.
Someofthemethodsusedforapplicationintegrationarediscussedinthefollowing
section.Thesemodelsinclude;
1.Presentationintegration
2.Dataintegrationand
3.Functionintegration
1.Presentationintegrationmodel
Allowstheintegrationofnewsoftwarethroughtheexistingpresentationsofthe
legacysoftware.
Thisistypicallyusedtocreateanewuserinterfacebutmaybeusedtointegrate
withotherapplications.
2.Dataintegrationmodel
Allowstheintegrationofsoftwarethroughaccesstothedatathatiscreated,
managedandstoredbythesoftwaretypicallyforthepurposesofreusingor
synchronizingdataacrossapplications.
3.Functionalintegrationmodel
Allowstheintegrationofsoftwareforthepurposeofinvokingexisting
functionalityfromotherneworexistingapplications.
Theintegrationisdonethroughinterfacestothesoftware.
FundamentalChallengesofIntegration
Tosupportcommonbusinessprocessesanddatasharingacrossapplications,these
applicationsneedtobeintegrated.
Applicationintegrationneedstoprovideefficient,reliableandsecuredataexchange
betweenmultipleenterprisesapplications.
AlotoftheproblemstobeaddressedinOrganizationsApplicationIntegrationsystem
fromhavingtointegratestandaloneapplicationswhichhavebeen

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Developedindependently,
Operateautonomously,and
Werenotoriginallyindentedtobeintegratedwithoneanother.
Integrationofapplications,developedbydifferentlanguagesandrunningondifferent
computingplatformsisnotaneasytask.
Bydefinition,integrationhastodealwithmultipleapplicationsrunningonmultiple
platformsindifferentlocations,makingtheterm‘simpleintegration’prettymuch
difficult.
Softwarevendorsofferapplicationintegrationsuitesthatprovidecross-platform,cross-
languageintegrationaswellastheabilitytointerfacewithmanypopularpackaged
businessapplications.
However,thistechnicalinfrastructurepresentsonlyasmallportionofthe
integrationcomplexities.
Thetruechallengesofintegrationspanfaracrossbusinessandtechnicalissues.
Allintegrationsolutionshavetodealwithafewfundamentalchallenges:someofthe
challengesofintegrationare;
Networkunreliability
Distributedsystems
Slownetworksand
Heterogeneity
Modificationcomplexity
1.Networkisunreliable.
Integrationsolutionshavetotransportdatafromonecomputertoanotheracross
networks.
Comparedtoaprocessrunningonasinglecomputer,distributedcomputinghas
tobepreparedtodealwithamuchlargersetofpossibleproblems.
Oftentimes,twosystemstobeintegratedareseparatedbycontinentsanddata
betweenthemhastotravelthroughphone-lines,LANsegments,routers,
switches,publicnetworks,andsatellitelinks.
Eachofthesestepscancausedelaysorinterruptions.

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2.Distributed–
Intheworstcase,everyapplicationrunsonacompletelyseparateenvironment,
E.g.databasestorageisnotsharedamongapplications.
Message-basedcommunicationistheonlypossibilitytoexchangeinformation.
3.Networksareslow.
Sendingdataacrossanetworkismultipleordersofmagnitudeslowerthan
makingalocalmethodcall.
Designingawidelydistributedsolutionthesamewayyouwouldapproacha
singleapplicationcouldhavedisastrousperformanceimplications
4.Anytwoapplicationsaredifferent.
Integrationsolutionsneedtotransmitinformationbetweensystemsthatuse
differentprogramminglanguages,operatingplatforms,anddataformats.
Anintegrationsolutionneedstobeabletointerfacewithallthesedifferent
technologies.
Heterogeneous–eachapplicationimplementsitsowndatamodel.
Conceptsmaybeshared,butrepresentationmismatchesaretobeexpected.
Mappingsandtransformationsarerequired.
5.Changeisinevitable.
Applicationschangeovertime.
Anintegrationsolutionhastokeeppacewithchangesintheapplicationsit
connects.
Integrationsolutionscaneasilygetcaughtinanavalancheeffectofchanges–if
onesystemchanges,allothersystemsmaybeaffected.
Anintegrationsolutionneedstominimizethedependenciesfromonesystemto
anotherbyusingloosecouplingbetweenapplications.
Autonomous–applicationsupdatetheirstateindependentlywithoutcoordinating
witheachother.

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Thesystemstobeintegratedaremaintainedindependentlyandupgradedat
differenttimes.
IntegrativeTechnologies/methodsforintegration
Applicationintegrationisanintegrationframeworkcomposedofacollectionof
technologiesandserviceswhichformamiddlewareor"middlewareframework"to
enableintegrationofsystemsandapplicationsacrossorganizations.
Therearefourmethodsusedinapplicationintegration,whicharediscussedinthesection
below:
1.FileTransfer-
Oneapplicationwritesafilethatanotherlaterreads.
Theapplicationsneedtoagreeonthefilenameandlocation,theformatofthe
file,thetimingofwhenitwillbewrittenandread,andwhowilldeletethefile.
2.SharedDatabase-
Multipleapplicationssharethesamedatabaseschema,locatedinasingle
physicaldatabase.
Becausethereisnoduplicatedatastorage,nodatahastobetransferredfrom
oneapplicationtotheother.
3.RemoteProcedureInvocation–
Oneapplicationexposessomeofitsfunctionalitysothatitcanbeaccessed
remotelybyotherapplicationsasaremoteprocedure.
Thecommunicationoccursreal-timeandsynchronously.
4.Messaging–
Oneapplicationpublishesamessagetoacommonmessagechannel.
Otherapplicationscanreadthemessagefromthechannelatalatertime.
Theapplicationsmustagreeonachannelaswellastheformatofthemessage.
Thecommunicationisasynchronous(onebyonecommunication)example
usingATMmachine.
Allofthefourapproachessolveessentiallythesameprobleminintegration;
eachstylehasitsdistinctadvantagesanddisadvantages.

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Infact,applicationsmayintegrateusingmultiplestylessuchthateachpointof
integrationtakesadvantageofthestylethatsuitsitbest.
Filetransfer
Anorganizationnaturally,runsmultipleapplicationsthatarebeingbuilt
independently,withdifferentlanguagesandplatforms.
Howcanweintegratemultipleapplicationssothattheyworktogetherandcanexchange
informationandinteractwitheachother?Theanswerforthisquestionisgivenbelow;
Oneofthepossiblesolutionstoallowtheseapplicationstobeintegratedis
allowingeachapplicationproducefilescontaininginformationthatother
applicationsneedtoconsume.
Integratorstaketheresponsibilityoftransformingfilesintodifferentformats.
Producethefilesatregularintervalsaccordingtothenatureofthebusiness,
whichcanbeconsumedorreadbyanotherfile.
Animportantdecisionwithfilesiswhatformattouse.
Veryrarelywilltheoutputofoneapplicationbeexactlywhat'sneededfor
another,soyou'llhavetodoafairbitofprocessingoffilesalongtheway.
Notjustdoalltheapplicationsthatuseafilehavetoreadit,youalsohavetobeableto
useprocessingtoolsonit.
SharedDatabase
Acommondatabasecanbeusedforintegratingapplications.
Asinglephysicaldatabasecanbesharedbydifferentapplicationsrunningondifferent
platforms.

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Thismethodintegratesapplicationsbyhavingthemstoretheirdatainasingleshared
database.
Ifafamilyofintegratedapplicationsallrelyonthesamedatabase,thenwecanbepretty
surethattheyarealwaysconsistentallofthetime.
Ifwedogetsimultaneousupdatestoasinglepieceofdatafromdifferentsources,then
wehavetransactionmanagementsystemsthathandlethataboutasgracefullyasitever
canbemanaged.
Remoteprocedurecalls
Thismethoddevelopseachapplicationwhichisrequiredtobeintegratedasalarge-
scaleobjectorcomponentwithencapsulateddataanditprovidesaninterfaceto
allowotherapplicationstointeractwiththerunningapplication.
RemoteProcedureInvocationappliestheprincipleofencapsulationtointegrating
applications.
oIfanapplicationneedssomeinformationthatisownedbyanotherapplication,it
asksthatapplicationdirectly.
oIfoneapplicationneedstomodifythedataofanother,thenitdoessobymakinga
calltotheotherapplication.
oEachapplicationcanmaintaintheintegrityofthedataitowns.

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Furthermore,eachapplicationcanalteritsinternaldatawithouthavingeveryother
applicationbeaffected.
Messaging
Messagingallowsinteractionbetweenapplicationspossible.
Messagepassingcanbeusedtotransferpacketsofdatafrequently,immediately,
reliably,andasynchronously,orsynchronouslyusingcustomizableformats.
Asynchronousmessagingisfundamentallyapracticalreactiontotheproblemsof
distributedsystems.
Sendingamessagedoesnotrequirebothsystemstobeupandreadyatthe
sametime.
Furthermore,thinkingaboutthecommunicationinanasynchronousmanner
forcesdeveloperstorecognizethatworkingwitharemoteapplicationisslower,
whichencouragesdesignofcomponentswithhighcohesion(lotsofworklocally)
andlowadhesion(selectiveworkremotely).
Thereasonamessagingsystemisneededtomovemessagesfromonecomputerto
anotheristhatcomputersandthenetworksthatconnectthemareinherentlyunreliable.
Justbecauseoneapplicationisreadytosendacommunicationdoesnotmeanthat
theotherapplicationisreadytoreceiveit.
Evenifbothapplicationsareready,thenetworkmaynotbeworking,ormayfailto
transmitthedataproperly.
Amessagingsystemovercomestheselimitationsbyrepeatedlytryingtotransmitthe
messageuntilitsucceeds.

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Underidealcircumstances,themessageistransmittedsuccessfullyonthefirsttry,but
circumstancesareoftennotideal.
Inessence,amessageistransmittedinfivesteps:
1.Create-thesendercreatesthemessageandpopulatesitwithdata.
2.Send-thesenderaddsthemessagetoachannel.
3.Deliver-themessagingsystemmovesthemessagefromthesender’scomputerto
thereceiver’scomputer,makingitavailabletothereceiver.
4.Receive-thereceiverreadsthemessagefromthechannel.
5.Process-thereceiverextractsthedatafromthemessage.
Thisdiagramillustratesthesefivetransmissionsteps,whichcomputerperformseach,and
whichstepsinvolvethemessagingsystem:
Thisdiagramalsoillustratestwoimportantmessagingconcepts:
1.Sendandforget–
Instep2,thesendingapplicationsendsthemessagetothemessagechannel.
Oncethatsendiscomplete,thesendercangoontootherworkwhilethe
messagingsystemtransmitsthemessageinthebackground.

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Thesendercanbeconfidentthatthereceiverwilleventuallyreceivethe
messageanddoesnothavetowaituntilthathappens.
2.Storeandforward–
Instep2,whenthesendingapplicationsendsthemessagetothemessagechannel,
themessagingsystemstoresthemessageonthesender’scomputer,eitherin
memoryorondisk.
Instep3,themessagingsystemdeliversthemessagebyforwardingitfromthe
sender’scomputertothereceiver’scomputer,andthenstoresthemessageonce
againonthereceiver’scomputer.
Thisstore-and-forwardprocessmayberepeatedmanytimes,asthemessageis
movedfromonecomputertoanother,untilitreachesthereceiver’scomputer.
MiddlewareandIntegrativearchitectures
Middlewareisasoftwareprogrammingrunningatthetopofoperatingsystemand
belowtheapplications.
Itconnectsapplicationsorsoftwarecomponents.
Middlewareprovidesastandardhighlevelinterfacetotheapplicationdevelopers
andintegrators,sothatapplicationcaneasilyinteroperate.
Interoperabilityistheabilityoftwoormorecomponentsorsystemstoexchange
information.

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Therearethreetypesofmiddleware.Theseare,transaction-oriented,object-oriented
andmessageorientedmiddleware.
1.Transaction-orientedmiddleware:supportsdistributedcomputinginvolving
databaseapplications.
2.Message-orientedmiddleware:supportsreliable,asynchronous
communicationsbetweendistributedcomponentsorapplications.
3.Object-orientedmiddleware:systemsarebasedonobject-orientedparadigm,
andprimarilysupportsynchronouscommunicationsbetweendistributedobjects
orsoftwarecomponents.ExamplesareCORBA,DCOMandRMI.
Integrativearchitectures
Integrativearchitecturesarethestandardmethodologiesforapplicationintegration.
Thesearchitecturesinclude,CORBA,DCOMandRPC.
Thearchitecturesactasamiddleware,asoftwareapplicationthatmediatesbetween
differentapplications.
CommonObjectRequestBrokerArchitecture
CORBAisasoftwarestandardthatisdefinedandmaintainedbytheObjectManagement
Group(OMG).
TheCommonObjectRequestBrokerArchitecture(CORBA)isastandardarchitecture
foradistributedobjectssystem.
CORBAisdesignedtoallowdistributedobjectstointeroperateinaheterogeneous
environment,whereobjectscanbeimplementedindifferentprogramminglanguage
and/ordeployedondifferentplatforms.

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DCOM
Distributedcomponentobjectmodel-extendstheCOMtosupportcommunication
betweenobjects.
DCOMisasoftwarearchitectureorremoteprotocolthatdefinesabinarystandardfor
componentinteroperability.
DCOMisasoftwarearchitecturethatallowsapplicationstobebuiltfrombinarysoftware
components.
Isbinaryinterfacestandardforsoftwarecomponents,thatallowsinter-process
communication.
Binaryinterfaceisaprograminterfacebetweenbinaryprogrammodulesoftenoneofthe
moduleislibraryoroperatingsystemandtheotherisuserprogrammodule.
Defineshowcomputationalroutinesarecalledinmachinecodeorlow-levelwhichis
hardwareindependent

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ReviewQuestions
1.Defineintegrativeprogramming?
2.Explainthearchitecturesusedinapplicationintegration?
3.Describeinteroperability?
4.Whatarethechallengesinapplicationintegrationdescribethesolutionsto
overcomethechallenges?
5.DescribethedifferencebetweenCORBAandRMIorremotemethodinvocation?
6.Explainintegrativetechnologiesormethodsusedinapplicationintegration?
7.Whatisthedifferencebetweendatalevelandfunctionlevelintegrationmodel?
Whichmodelismorecomplexandwhy?
8.Whatisheterogeneity?
9.Describedifferenttypesofmiddlewareanddescribehowthemiddlewaresolves
problemofheterogeneity?

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CHAPTER2
WebServicesandMiddleware;Networkprogramming;Lowleveldata
communicationsMessageandqueuingservices
CourseLearningOutcome:
Attheendofthesemester,thestudentswillbeableto:
1.DescribetheWebServicesandMiddleware;
2.IdentifythepartsofNetworkProgramming;and
3.Modifyalowleveldatacommunicationsmessageandqueuingservices.
WebServicesandMiddleware
Applicationintegrationtechnology
Allowsapplicationstobeintegratedmorerapidly,easilyandlessexpensively.
Program-to-programinteractionswhereaswebforprogram-to-userinteractions.
Allowcompaniestoreducethecostofdoinge-business,todeploysolutionsfasterand
toopenupnewopportunities.
Webservicesmodelbuiltonemergingstandardssuchas
HTTP
XML
SimpleObjectAccessProtocol(SOAP)
WebServicesDescriptionLanguage(WSDL)
UniversalDescription,DiscoveryandIntegration(UDDI)
Developedinordertodistributeanobjectandserveittovarioususersintheweb
environments.
Usedintheserversituationswhilesolvingtheweb-scalabilityproblemoftheother
distributedobjecttechnologies.
WSDLandSOAPexploitXML.
WSDLisanXMLdescribingthewebservice.
SOAPisanXMLdescribingthecalledmethod,itsparameters,anditsreturnvalue,
canbedeliveredovertheHTTP

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WebServicesandMiddleware
1.Aclientthatwantstobeservicedshouldfirstfindthesupportedservicesfromthepre-
existingregistrybeforecompilingacode.
2.Afterfindingitsservicesthroughsearching,theclientgainstheWebService
DescriptionLanguage(WSDL)thataserverpreviouslyregisters.
FromtheWSDL,theclientknowstheserviceproviderlocationandthe
parameterstothefoundmethod.
3.Aftertheclientbindsthedescribedserviceduringthecompiletime,itcallsthelocal
agentwhenevertheclientinvokesamethodcall,andthelocalagentdeliversittothe
serversideagentthroughSimpleObjectAccessProtocol(SOAP)overHTTP,FTP,
SMTP,andTCPduringtheruntime.
4.Theserversideagentactivatestheappropriateobject,anddeliversthecallstotheobject.
NetworkProgramming
Network:
Anetworkisacollectionofcomputersandotherdevicesthatcansenddatatoand
receivedatafromeachother.

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Anetworkisoftenconnectedbywires.
However,wirelessnetworkstransmitdatathroughinfraredlightand
microwaves.
Node:
Eachmachineonanetworkiscalledanode.
Mostnodesarecomputers,butprinters,routers,bridges,gatewaysetc.canalso
benodes.
Nodesthatarefullyfunctionalcomputersarealsocalledhosts.
Packet:
Allmoderncomputernetworksarepacket-switchednetworks:datatravelingon
thenetworkisbrokenintochunkscalledpacketsandeachpacketishandled
separately.
Eachpacketcontainsinformationaboutwhosentitandwhereit'sgoing.
Protocol:
Aprotocolisaprecisesetofrulesdefininghowcomputerscommunicate:the
formatofaddresses,howdataissplitintopackets.
IP:
IPwasdesignedtoallowmultipleroutesbetweenanytwopointsandtoroute
packetsofdataarounddamagedrouters.
TCP:
Sincetherearemultipleroutesbetweentwopointsandthepacketsthatmakeupa
particulardatastream.
Furthermore,theymaynotarriveintheordertheyweresent,iftheyevenarriveat
all.
UDP:
UDPisunreliableprotocolsthatdoesnotguaranteethatpacketswillarriveat
theirdestinationorthattheywillarriveinthesameordertheyweresent.
Ports:
EachcomputerwithanIPaddresshasseveralthousandlogicalports.
Eachportisidentifiedbyanumberbetween1and65,535.

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Eachportcanbeallocatedtoaparticularservice.
Portnumbers1through255arereservedbyIPforwell-knownservices.
Ifyouconnecttoport80ofahost,forinstance,youmayexpecttofindanHTTP
server.
Internet:
LargestIP-basednetworkforconnectingmachinestogether.
Java:easy-to-use,cross-platformmodelfornetworkcommunications.
WhatisaSocket?
SocketsareameansofusingIPtocommunicatebetweenmachines,sosocketsallow
Javatointeroperatewithlegacysystemsbysimplytalkingtoexistingserversusingtheir
pre-definedprotocol.
Internetprotocol:UserDatagramProtocol(UDP)andTransmissionControlProtocol
(TCP).
InternetAddressesorIPAddresses
Everynetworknodehasanaddress,aseriesofbytesthatuniquelyidentifyit.
InternetaddressesaremanipulatedinJavabytheuseoftheInetAddress
class.InetAddresstakescareoftheDomainNameSystem(DNS)look-upand
reverselook-up;
IPaddressescanbespecifiedbyeitherthehostnameortherawIPaddress.
InetAddressprovidesmethodstogetByName(),getAllByName(),getLocalHost(),
getAddress(),etc.
IPaddressesarea32-bitnumber,oftenrepresentedasa"quad"offour8-bitnumbers
separatedbyperiods.
Theyareorganizedintoclasses(A,B,C,D,andE).
Forexample126.255.255.255Client/ServerComputing-Javalanguage
communicatewithremotefilesystem.
HowUDPclientsandUDPserverscommunicateoversocketsCreatingUDP
Servers:
TocreateaserverwithUDP,dothefollowing:
1.CreateaDatagramSocketattachedtoaport.

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intport=1234;
DatagramSocketsocket=newDatagramSocket(port);
2.Allocatespacetoholdtheincomingpacket,andcreateaninstanceof
DatagramPackettoholdtheincomingdata.
byte[]buffer=newbyte[1024];
DatagramPacketpacket=newDatagramPacket(buffer,buffer.length);
3.Blockuntilapacketisreceived,thenextracttheinformationyouneedfromthe
packet.
//Blockonreceive()
socket.receive(packet);
//Extractthepacketdata
byte[]data=packet.getData();
//Findoutwherepacketcamefrom
//sowecanreplytothesamehost/portInetAddressremoteHost=
packet.getAddress();intremotePort=packet.getPort();
CreatingUDPClients
1.Firstallocatespacetoholdthedatawearesendingandcreateaninstanceof
DatagramPackettoholdthedata.
byte[]buffer=newbyte[1024];
intport=1234;
InetAddresshost=InetAddress.getByName("magelang.com");
DatagramPacketpacket=newDatagramPacket(buffer,buffer.length,host,
port);
2.CreateaDatagramSocketandsendthepacketusingthissocket.
DatagramSocketsocket=newDatagramSocket();//freelocalporttouse
socket.send(packet);
//FindoutwherewearesendingfromInetAddresslocalHostname=
socket.getLocalAddress();intlocalPort=socket.getLocalPort();
HowTCPclientsandTCPserverscommunicateoversocketsCreatingTCPServers:
TocreateaTCPserver,dothefollowing:
1.CreateaServerSocketattachedtoaportnumber.

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ServerSocketserver=newServerSocket(port);
2.Waitforconnectionsfromclientsrequestingconnectionstothatport.
//Blockonaccept()
Socketchannel=server.accept();
You'llgetaSocketobjectasaresultoftheconnection.
3.Getinputandoutputstreamsassociatedwiththesocket.
out=newPrintWriter(channel.getOutputStream());out.println("Hey!I
heardyouoverthissocket!");
reader=newInputStreamReader(channel.getInputStream());in=new
BufferedReader(reader);
Nowyoucanreadandwritetothesocket,thus,communicatingwiththeclient.
Stringdata=in.readLine();
CreatingTCPClients:
TocreateaTCPclient,dothefollowing:
1.CreateaSocketobjectattachedtoaremotehost,port.
Socketclient=newSocket(host,port);
Whentheconstructorreturns,youhaveaconnection.
2.Getinputandoutputstreamsassociatedwiththesocket.
out=newPrintWriter(client.getOutputStream());out.println("Watson!"+
"Comehere...Ineedyou!");
reader=newInputStreamReader(client.getInputStream());in=new
BufferedReader(reader);
Nowyoucanreadandwritetothesocket,thus,communicatingwiththeserver.
Stringdata=in.readLine();
LowLevelDataCommunication
TCP/IP(TransmissionControlProtocol/InternetProtocol)
oTheProtocoluponwhichthewholeInternetisbased
oEachnodemustbeconfiguredforTCP/IPtofunctionproperly.
oAsoftware-basedprotocol
oTCP/IPisbasicallythebindingtogetherofInternetProtocolsusedtoconnect
hostsontheinternet-MainonesareIPandTCP

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oTCPandIPhavespecialpacketstructure
oIP(InternetProtocol)isresponsiblefordeliveringpacketsofdatabetweensystems
ontheinternetandspecifiestheirformat.Packetsforwardedbasedonafourbyte
destinationIPaddress(IPnumber)IPDOESNOTMAKEGUARANTEES!Itis
verysimple-essentially:sendandforget.
oTCP(TransmissionControlProtocol)isresponsibleforverifyingthecorrect
deliveryofdata/packetsfromclienttoserver.Datacanbelost.SoTCPalsoadds
supporttodetecterrorsandretransmitdatauntilcompletelyreceived.
IPPacketStructure
Version-IndicatestheversionofIPcurrentlyused.
IPHeaderLength(IHL)-Indicatesthedatagramheaderlengthin32-bitwords.
Type-of-Service-Specifieshowanupper-layerprotocolwouldlikeacurrentdatagram
tobehandled,andassignsdatagramvariouslevelsofimportance.

23. IntegrativeProgramming
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TotalLength-Specifiesthelength,inbytes,oftheentireIPpacket,includingthedataand
header.
Identification-Containsanintegerthatidentifiesthecurrentdatagram.Thisfieldis
usedtohelppiecetogetherdatagramfragments.
Flags-Consistsofa3-bitfieldofwhichthetwolow-order(least-significant)bitscontrol
fragmentation.Thelow-orderbitspecifieswhetherthepacketcanbefragmented.The
middlebitspecifieswhetherthepacketisthelastfragmentinaseriesoffragmented
packets.Thethirdorhigh-orderbitisnotused.
FragmentOffset-Indicatesthepositionofthefragment’sdatarelativetothebeginningof
thedataintheoriginaldatagram,whichallowsthedestinationIPprocesstoproperly
reconstructtheoriginaldatagram.
Time-to-Live-Maintainsacounterthatgraduallydecrementsdowntozero,atwhich
pointthedatagramisdiscarded.
Protocol-Indicateswhichupper-layerprotocolreceivesincomingpacketsafterIP
processingiscomplete.
HeaderChecksum-HelpsensureIPheaderintegrity.
SourceAddress-Specifiesthesendingnode.
DestinationAddress-Specifiesthereceivingnode.
Options-AllowsIPtosupportvariousoptions,suchassecurity.
Data-Containsupper-layersentinpacket.
TCPPacketStructure

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Thereare12fieldsinTCPPacket:
SourcePortandDestinationPort-Identifiespointsatwhichupperlayersource
anddestinationprocessesreceiveTCPservices.
SequenceNumberIntheconnection-establishmentphase,thisfieldalsocanbe
usedtoidentifyaninitialsequencenumbertobeusedinanupcoming
transmission.
AcknowledgmentNumber-Containsthesequencenumberofthenextbyteof
datathesenderofthepacketexpectstoreceive.
DataOffset-Indicatesthenumberof32-bitwordsintheTCPheader.
Reserved-Remainsreservedforfutureuse.

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Flags-Carriesavarietyofcontrolinformation,includingtheSYNandACKbits
usedforconnectionestablishment,andtheFINbitusedforconnection
termination.
Window-Specifiesthesizeofthesender’sreceivingwindow(thatis,thebuffer
spaceavailableforincomingdata).
Checksum-Indicateswhethertheheaderwasdamagedintransit.
UrgentPointer-Pointstothefirsturgentdatabyteinthepacket.
Options-SpecifiesvariousTCPoptions.
Data-Containsupper-layersentinpacket.

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Chapter3
DataMappingandExchange
CourseLearningOutcome:
Attheendofthesemester,thestudentswillbeableto:
1.DiscussDataMappingandExchange;
2.DefineaComplexElementusingXMLScheme;and
3.CreateXMLSchemasbyUsingXMLSchema-CreationTools.
XMLDTDandXMLSchema
HowdoesanXMLprocessorcheckyourxmldocument?
TherearetwomainchecksthatXMLprocessorsmake:
1.Checkingthatyourdocumentiswell-formed(Syntaxrule)
2.Checkingthatit'svalid(syntax-checkyourXMLeitherinXMLDTDorXSD)
DTD-DocumentTypeDefinition
XSD-XMLSchemaDefinition
WhyneedXMLValidator
UseourXMLvalidatortosyntax-checkyourXML.
ErrorsinXMLdocumentswillstopyourXMLapplicationsunlikeHTMLbrowser
XMLDTD
AnXMLdocumentwithcorrectsyntaxiscalled"WellFormed".
AnXMLdocumentvalidatedagainstaDTDis"WellFormed"and"Valid".
ThepurposeofaDTDistodefinethestructureofanXMLdocumentandalistof
legalelements.
HowyouaddaDTDtoourXMLdocument
1.DTDscanbeseparatedocuments(or)
2.TheycanbebuiltintoanXMLdocumentusingaspecialelementnamed<!DOCTYPE>.
AnXMLDocumentwithaDTD(example4.xml)
<?xmlversion="1.0"encoding="UTF-8"?>
<?xml-stylesheettype="text/css"href="css1.css"?>

27. IntegrativeProgramming
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<!DOCTYPEdocument
[
<!ELEMENTdocument(heading,message)>
<!ELEMENTheading(#PCDATA)>
<!ELEMENTmessage(#PCDATA)>
]>
<document>
<heading>HelloFromXML</heading>
<message>ThisisanXMLdocument!</message>
</document>
ValidXMLDocumentwithDTD(example.5.xml)
TheDOCTYPEdeclarationisareferencetoanexternalDTDfile"Note.dtd“
<?xmlversion="1.0"encoding="UTF-8"?>
<!DOCTYPEnoteSYSTEM"Note.dtd">
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don'tforgetmethisweekend!</body>
</note>
Note.dtd
<!DOCTYPEnote[
<!ELEMENTnote(to,from,heading,body)>
<!ELEMENTto(#PCDATA)>
<!ELEMENTfrom(#PCDATA)>
<!ELEMENTheading(#PCDATA)>
<!ELEMENTbody(#PCDATA)>
]>
TheDTDaboveisinterpretedlikethis:
!DOCTYPEnotedefinesthattherootelementofthedocumentisnote

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!ELEMENTnotedefinesthatthenoteelementcontainsfourelements:"to,from,
heading,body"
!ELEMENTtodefinesthetwoelementtobeoftype"#PCDATA"
!ELEMENTfromdefinesthefromelementtobeoftype"#PCDATA"
!ELEMENTheadingdefinestheheadingelementtobeoftype"#PCDATA"
!ELEMENTbodydefinesthebodyelementtobeoftype"#PCDATA“
Note
#PCDATAmeansparse-abletextdata.
WhenNOTtoUseaDocumentDefinition?
WhenyouareworkingwithsmallXMLfiles,creatingdocumentdefinitionsmaybea
wasteoftime.
XMLSchema
AnotherwayofvalidatingXMLdocuments:usingXMLschemas.
TheXMLSchemalanguageisalsoreferredtoasXMLSchemaDefinition(XSD),
describesthestructureofanXMLdocument.
Definesthelegalbuildingblocks(elementsandattributes)ofanXMLdocumentlike
DTD.
defineswhichelementsarechildelements
definesthenumberandorderofchildelements
defineswhetheranelementisemptyorcanincludetext
definesdatatypesforelementsandattributes
definesdefaultandfixedvaluesforelementsandattributes
XMLSchemaswillbeusedinmostWebapplicationsasareplacementforDTDs.Herearesome
reasons:
XMLSchemasareextensibletofutureadditions
XMLSchemasarericherandmorepowerfulthanDTDs
XMLSchemasarewritteninXML
XMLSchemassupportdatatypesandnamespaces
CreatingXMLSchemasbyUsingXMLSchema-CreationTools
HiTSoftware

29. IntegrativeProgramming
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xmlArchitect
XMLspy
XMLRay
MicrosoftVisualStudio.NET
XSDSimpleElement
Thesyntaxfordefiningasimpleelement
DefaultandFixedValuesforSimpleElements
XSDAttributes
Thesyntaxfordefininganattribute
DefaultandFixedValuesforAttributes
OptionalandRequiredAttributes
XSDComplexElements
HowtoDefineaComplexElementusingXMLScheme
XSDEmptyElements
XSDIndicators
Orderindicatorsare:
All
Choice
Sequence
XSDSimpleElement
AsimpleelementisanXMLelementthatcancontainonlytext.
Itcannotcontainanyotherelementsorattributes.
XMLSchemahasalotofbuilt-indatatypes.Themostcommontypesare:
1.xs:string
2.xs:decimal
3.xs:integer
4.xs:boolean
5.xs:date
6.xs:time
Thesyntaxfordefiningasimpleelementis:
<xs:elementname="xxx"type="yyy"/>
Example
<lastname>Refsnes</lastname>

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<age>36</age>
<dateborn>1970-03-27</dateborn>
<xs:elementname="lastname"type="xs:string"/>
<xs:elementname="age"type="xs:integer"/>
<xs:elementname="dateborn"type="xs:date"/>
DefaultandFixedValuesforSimpleElements
Simpleelementsmayhaveadefaultvalueorafixedvaluespecified.
1.Adefaultvalueisautomaticallyassignedtotheelementwhennoothervalueis
specified.
<xs:elementname="color"type="xs:string"default="red"/>
2.Afixedvalueisalsoautomaticallyassignedtotheelement,andyoucannot
specifyanothervalue.
<xs:elementname="color"type="xs:string"fixed="red"/>
XSDAttributes
Simpleelementscannothaveattributes.
Ifanelementhasattributes,itisconsideredtobeofacomplextype.Buttheattribute
itselfisalwaysdeclaredasasimpletype.
Thesyntaxfordefininganattributeis:
<xs:attributename="xxx"type="yyy"/>
Example
<lastnamelang="EN">Smith</lastname>
<xs:attributename="lang"type="xs:string"/>
DefaultandFixedValuesforAttributes
Attributesmayhaveadefaultvalueorafixedvaluespecified.
<xs:attributename="lang"type="xs:string"default="EN"/>
<xs:attributename="lang"type="xs:string"fixed="EN"/>
OptionalandRequiredAttributes
Attributesareoptionalbydefault.Tospecifythattheattributeisrequired,usethe"use"
attribute:
<xs:attributename="lang"type="xs:string"use="required"/>
XSDComplexElements

31. IntegrativeProgramming
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AcomplexelementisanXMLelementthatcontainsotherelementsand/orattributes.
Therearefourkindsofcomplexelements:
Example:
1.AcomplexXMLelement,"product",whichisempty:<productpid="1345"/>
2.AcomplexXMLelement,"employee",whichcontainsonlyotherelements:
<employee>
<firstname>John</firstname>
<lastname>Smith</lastname>
</employee>
3.AcomplexXMLelement,"food",whichcontainsonlytext:
<foodtype="dessert">Icecream</food>
4.AcomplexXMLelement,"description",whichcontainsbothelementsandtext:
<description>
Ithappenedon<datelang=“EN">03.03.99</date>
</description>
HowtoDefineaComplexElementusingXMLScheme
ComplexXMLelement,"employee",whichcontainsonlyotherelements:
<employee>
<firstname>John</firstname>
<lastname>Smith</lastname>
</employee>
The"employee"elementcanbedeclareddirectlybynamingtheelement:
<xs:elementname="employee">
<xs:complexType>
<xs:sequence>
<xs:elementname="firstname"type="xs:string"/>
<xs:elementname="lastname"type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
Anemptycomplexelementcannothavecontents,onlyattributes.

32. IntegrativeProgramming
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<productprodid="1345"/>
Itispossibletodeclarethe"product"elementmorecompactly:
<xs:elementname="product">
<xs:complexType>
<xs:attributename="prodid"type="xs:positiveInteger"/>
</xs:complexType>
</xs:element>
XSDIndicators
Howelementsaretobeusedindocumentswithindicators.
Orderindicatorsareusedtodefinetheorderoftheelements.Theyare:
1.All
2.Choice
3.Sequence
AllIndicator:
The<all>indicatorspecifiesthatthechildelementscanappearinanyorder,andthat
eachchildelementmustoccuronlyonce:
<xs:elementname="person">
<xs:complexType>
<xs:all>
<xs:elementname="firstname"type="xs:string"/>
<xs:elementname="lastname"type="xs:string"/>
</xs:all>
</xs:complexType>
</xs:element>
ChoiceIndicator:
The<choice>indicatorspecifiesthateitheronechildelementoranothercanoccur:
<xs:elementname="person">
<xs:complexType>
<xs:choice>
<xs:elementname="employee"type="employee"/>
<xs:elementname="member"type="member"/>

33. IntegrativeProgramming
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</xs:choice>
</xs:complexType>
</xs:element>
SequenceIndicator:
The<sequence>indicatorspecifiesthatthechildelementsmustappearinaspecificorder:
<xs:elementname="person">
<xs:complexType>
<xs:sequence>
<xs:elementname="firstname"type="xs:string"/>
<xs:elementname="lastname"type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
XMLExample(“note.xml”)
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don'tforgetmethisweekend!</body>
</note>
XSDExample(“note.xsd”)
<xs:elementname="note">
<xs:complexType>
<xs:sequence>
<xs:elementname="to"type="xs:string"/>
<xs:elementname="from"type="xs:string"/>
<xs:elementname="heading"type="xs:string"/>
<xs:elementname="body"type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>

34. IntegrativeProgramming
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Example(shiporder.xml):
<?xmlversion="1.0"encoding="ISO-8859-1"?>
<shiporderorderid="889923">
<orderperson>JohnSmith</orderperson>
<shipto>
<name>OlaNordmann</name>
<address>Langgt23</address>
<city>4000Stavanger</city>
<country>Norway</country>
</shipto>
</shiporder>
Example"shiporder.xsd":
<?xmlversion="1.0"encoding="ISO-8859-1"?>
<xs:schemaxmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:elementname="shiporder">
<xs:complexType>
<xs:sequence>
<xs:elementname="orderperson"type="xs:string"/>
<xs:elementname="shipto">
<xs:complexType>
<xs:sequence>
<xs:elementname="name"type="xs:string"/>
<xs:elementname="address"type="xs:string"/>
<xs:elementname="city"type="xs:string"/>
<xs:elementname="country"type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attributename="orderid"type="xs:string"use="required"/>
</xs:complexType>

35. IntegrativeProgramming
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</xs:element>
</xs:schema>
XMLParser(ParsingXMLdocuments)
Allmodernbrowsershaveabuilt-inXMLparser.
AnXMLparserconvertsanXMLdocumentintoanXMLDOMobjectwhichcan
thenbemanipulatedwithJavaScript.
ParseanXMLDocument
ThefollowingcodefragmentparsesanXMLdocumentintoanXMLDOMobject:if
(window.XMLHttpRequest)
{//codeforIE7+,Firefox,Chrome,Opera,Safarixmlhttp=newXMLHttpRequest();
}
else
{//codeforIE6,IE5
xmlhttp=newActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.open("GET","books.xml",false);
xmlhttp.send();
xmlDoc=xmlhttp.responseXML;
XMLDOM
TheXMLDOMdefinesastandardwayforaccessingandmanipulatingXMLdocuments.
TheXMLDOMviewsanXMLdocumentasatree-structure.
AllelementscanbeaccessedthroughtheDOMtree.
Theircontent(textandattributes)canbemodifiedordeleted,andnewelementscanbe
created.
Theelements,theirtext,andtheirattributesareallknownasnodes.
TheHTMLDOM
TheHTMLDOMdefinesastandardwayforaccessingandmanipulatingHTML
documents.
AllHTMLelementscanbeaccessedthroughtheHTMLDOM.

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LoadanXMLFile-Cross-browser
parsesanXMLdocument("note.xml")intoanXMLDOMobjectandthenextractssome
informationfromitwithaJavaScript:
Example
<html>
<body>
<spanid="to"></span>
<spanid="from"></span>
<spanid="message"></span>
<script>
if(window.XMLHttpRequest)
{
//codeforIE7+,Firefox,Chrome,Opera,Safarixmlhttp=newXMLHttpRequest();
}
else
{
//codeforIE6,IE5
xmlhttp=newActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.open("GET","note.xml",false);
xmlhttp.send();
xmlDoc=xmlhttp.responseXML;
document.getElementById("to").innerHTML=
xmlDoc.getElementsByTagName("to")[0].childNodes[0].nodeValue;
document.getElementById("from").innerHTML=
xmlDoc.getElementsByTagName("from")[0].childNodes[0].nodeValue;
document.getElementById("message").innerHTML=
xmlDoc.getElementsByTagName("message")[0].childNodes[0].nodeValue;
</script>
</body>

37. IntegrativeProgramming
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</html>