Module1 Mobile Computing Architecture

Three Tier Architecture, Design Consideration for Mobile Computing, Architecture of Mobile Computing

1. Client layers of the
optical layer
Module 1
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2. Architecture for mobile computing
ThefirstlayerisUserInterfaceorPresentationTier.
Dealswithuserfacingdevicehandlingandrendering
Includesausersysteminterfacewhereuserservicesreside
SecondtieristheProcessManagementorApplicationTier.
Herebusinesslogicandrulesareexecuted.
Capableofaccommodatinghundredsofusers
Controlstransactions
Asynchronousqueuingtoensurereliablecompletionoftransactions.
ThirdtierisDatabaseManagementorDataTier
Fordatabaseaccessanddesign
Providesincreasedperformance,flexibility,maintainability,reusabilityandscalability,
whilehidingthecomplexityofdistributedprocessingfromtheuser
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3. Three-tier architecture for mobile
computing
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4. Three-tier architecture (in detail)
Tohaveuniversalaccess,theserverisconnectedtoa
ubiquitousnetworklikeinternet.
Tohaveaccesswithnetwork,anapplicationcalledweb
browserisrequiredsuchasInternetexplorer,Mozillaetc
Threelayers
PresentationTier(Tier1)
ApplicationTier(Tier2)
DataTier(Tier3)
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5. The mobile
computing
architecture
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6. Presentation Tier (Tier 1)
Firsttier
Layerofagentsapplicationsandsystems.
Applicationsrunontheclientdeviceandofferalltheuser
interfaces.
Responsibleforpresentingtheinformationtotheenduser.
Humansuseaudioandvideotoreceiveinformationfromthe
machine
Informationisgiventothesystemfromkeyboard(computer,
laptop,cellphones),pen(tablet,palmtop)etc
Itincludeswebbrowsers
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7. Application Tier (Tier 2)
Consideredasengineoftheapplication
Performsthebusinesslogicoftheprocessinginput,obtainingdataand
makingdecisions.
IncludestechnologieslikeCGIs,Java,JSP,.NETservices,PHPetc.deployed
inproductssuchasApache,Websphereetc.
Tierispresentationanddatabaseindependent.
Operationssuchasnetworkmanagement,securityareperformedusinga
middlewaresoftware
Middlewareisdefinedasalayerofsoftware,whichsitsinbetweenthe
operatingsystemanduserfacingsoftware.
Canalsobedefinedasasoftwaregatewayconnectingtwoindependentopen
objects.
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8. Middleware categories
Message-orientedMiddleware(MOM)
Transactionprocessing(TP)Middleware
DatabaseMiddleware
CommunicationMiddleware
DistributedObjectandComponents
TranscodingMiddleware
InternetContentAdaptionprotocol(ICAP)
Webservices
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9. Message-oriented Middleware (MOM)
Itconnectsdifferentapplicationsthroughasynchronousexchangeofmessages.
Worksoveranetworkedenvironmentwithoutknowingwhatplatformor
processortheotherapplicationisresidenton.
Themessagecancontainformatteddata,requestsforactionsorunsolicited
response.
Providesamessagequeuebetweenanytwointeroperatingapplications.
Ifthedestinationprocessisbusy,thenmessageisheldintemporarystorage
untilitisprocessed.
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10. Itisasynchronous,peertopeer,worksin
Publish/Subscribefashion.
Inthismode,oneormoreobjectssubscribetoanevent.
Aseventoccursitwillbepublishedbythelooselycoupled
asynchronousobject.
MOMwillnotifyaboutthisevent,Isappropriateforevent
drivenapplications
Eg:MessageQueuefromIBMknownasMQseries
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11. Transaction Processing (TP) middleware
Itprovidestoolsandenvironmentfordevelopingtransactionbaseddistributed
applications.
Inputsthedataintoasystematpointofinformationsourceandoutputthe
dataatinformationsink.
Usedindatamanagement,networkaccess,securitysystems,deliveryorder
processing,airlinereservations,customerserviceetc
Capableofprovidingservicestothousandsofclientsinadistributedclient/
serverenvironment.
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12. Includesfeaturessuchasrestartingfailedprocess,
dynamicloadbalancingandensuringconsistencyofdata.
Independentofdatabasearchitecture.
Itoptimisestheuseofresourcesbymultiplexingmany
clientfunctionsontomuchsmallersetofapplication
serviceroutines.
Eg:MVC
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13. Transaction processing middleware
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14. Model view controller MVC
JavausesMVCarchitecture,whichisanexampleofTPmiddleware
Itsplitsapplicationintoseparatelayersi.e.presentation,domainlogicand
dataaccess.
Model
domainspecificrepresentationoftheinformationonwhichtheapplicationoperates.
Domainlogicmanipulatesandaddsthemeaningtotherawdata
View
Responsibleforrenderingthemodelintoaformsuitableforinteractionandunderstoodby
theuser
Controller
Managestheprocessandrespondstoevents,typicallyuseractions,mayinvokechangesin
themodel
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15. Communication middleware
Similartoconnectingoneapplicationtoanotherwiththe
helpoftelnet
Usedintelecommunicationworld
Userinterfaceisthroughtelnet
Amediationserverautomatesthetelnetprotocolto
communicatewiththesenodesinthenetwork.
Eg:TN5250,TN3270
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16. Distributed Object and Components
Eg:CORBA(CommonObjectRequestBrokerArchitecture)
Opendistributedcomputinginfrastructurebeingstandardized
byobjectmanagementgroup.
Isvendor–independentinfrastructure.
CORBAbasedprogramfromanyvendoronalmostanycomputer,
operatingsystem,programminglanguageandnetworkcan
interoperatewithaCORBAbasedprogramfromsameor
anothervendor
Handleslargenumberofclientsathighrateswithhigh
reliability.
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17. Transcoding Middleware
Usedtotranscodeoneformatofdatatoanothertosuitthe
needoftheclient.
Toaccesswebpagesonphone,theHTMLpagesaretranscoded
intoWMLpagessothatmobilephonecanaccessit.
Itisusedforcontentadaptationtofittheneedofthedevice.
Contentadaptationisalsorequiredtomeetthenetwork
bandwidth.
Contentadaptationisdonethroughproprietaryprotocols
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18. Internet Content Adaptation Protocol
(ICAP)
Contentspresentintheinternetisaccessedfromdifferent
agentsanddevices.
Isaprotocolaimedatprovidingsimpleobjectbasedcontent
vectoringforHTTPservices.
LightweightprotocoltodotranscodingonHTTPmessages.
AllowsICAPclientstopassHTTPmessagestoICAPserversfor
somesortoftransformation.
Theserversendsbackthetransformedmessagesbacktoits
clients.
Beforedocumentisdisplayedfortheagent,itischeckedvirus.
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19. Typical data flow in ICAP environment
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20. Steps performed
TheuseragentmakesarequesttoanICAPclientforanobject
onanobjectserver.
TheclientsendstherequesttotheICAPserver
TheICAPserverexecutestheICAPresourceserviceonthe
requestandsendsthepossiblymodifiedrequestoraresponse
totherequestICAPclient
Theclientsendstherequest,possiblydifferentfromthe
originalclient’srequesttotheoriginalserver.
Theoriginserverrespondstotherequest
TheICAPclientsendsthereplytotheclient.
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21. Services provided by ICAP servers
Viruscheckingfortherequestedcontent
ContentfilteringbasedonthesensorratinglikePG(
parentalguidance),R(Restricted)
Localrealtimeadvertisementinsertionliketelevision
Wirelessprotocoltranslation
Imagemagnificationforelderly
Peertopeercompression
Encryptionofdataandmanymore.
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22. Web services
Itprovidesastandardmeansofcommunicationandinformationexchangeamong
differentsoftwareapplications,runningonavarietyofplatformsorframeworks.
IsasoftwaresystemidentifiedbyURLwhosepublicinterfacesandbindingsare
definedusingXML
Thebasicarchitectureincludeswebservicetechnologiescapableof:
Exchangingmessages
Describingwebservices
Publishinganddiscoveringwebservicedescriptions.
Webservicesarchitecturedefinesthestandardforexchangeofmessages
betweentheservicerequesterandserviceprovider.
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23. Serviceprovidersareresponsibleforpublishinga
descriptionoftheservicestheyprovide
Requestersmustbeabletofindanddiscoverdescriptions
oftheservices.
Softwareagentsinthebasicarchitecturecantakeonone
orallofthefollowing:
Servicerequester:requeststheexecutionofthewebservice
Serviceprovider:processesawebservicerequest
Discoveryagency:agencythroughwhichawebservicedescription
ispublishedandmadediscoverable.
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24. Data (Tier 3)
Usedtostoredataneededbytheapplicationandactsas
repositoryforbothtemporaryandpermanentdata.
Thedatacanbestoredinanyformofdatastoreor
database.
DatacanbestoredinXMLformatforinteroperabilitywith
othersystemsanddatasources.
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25. Database Middleware
Databaseindependencehelpsinmaintenanceofthesystembetter.
Allowsthebusinesslogictobeindependentandtransparentofthedatabase
technologyandthedatabasevendor.
Runsbetweentheapplicationprogramandthedatabase.
Alsocalledasdatabaseconnectorsaswell.
Eg:ODBC,JDBC
Withthehelpofthesemiddleware's,theapplicationwillbeabletoaccess
datafromanydatasource.
Datasourcescanbetextfiles,flatfiles,spreadsheetsornetwork,relational
,indexed,hierarchical,XMLdatabaseetc.
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26. SyncML
Isaprotocolisanemergingstandardforsynchronizationofdataaccessform
differentnodes.
Newindustryinitiativetodevelopandpromoteasinglecommondata
synchronizationprotocolthatcanbeusedindustrywide.
Supportsthenamingandidentificationofrecordsandcommonprotocol
commandstosynchronizelocalandnetworkdata.
Supportsidentificationandresolutionofsynchronizationconflicts.
Itworksoverallnetworksusedbymobiledevicesbothwirelessandwireline.
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27. Design consideration for mobile
computing
Thetermcontextmeans,alltheinformationthathelpsdeterminethestateofan
objectoractor
Itcanbeaperson,device,aplace,aphysicalorcomputationalobject.
Contentwithcontextawareness
Buildeachapplicationwithcontextawareness
Therearedifferentservicesfordifferentclientcontext
Bankprovidingservicesoninternet,formobilephonesandPDA
HavedifferentURLforeachtypeofdevice
Contentswitchoncontext
Providesadaptationofcontentwithinservice
Transparenttotheclient
Hereserviceisthesameforinternet,PDAandWAP
AllaccessthebanksitefromsameURL
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28. Contenttranscodingoncontext
Performstheadaptationofcontentbasedonthecontextand
behaviourofthedevice
Transparentfortheclientandtheapplication
Middlewareisusedtoperformalltheoperation
MiddlewareisintelligenttoconvertfromHTMLtoXMLorvice
versaasneedoccurs.
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29. Client Context Manager
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30. Identityinformation
Thedevicewillbeinapositiontocommunicateitsidentitywithoutanyambiguity
Spatialinformation
Informationrelatedtosurroundingspacei.e.location,orientation,speed,elevationand
acceleration
Temporalinformation
Informationrelatedtotimesuchastimeofday,date,timezone,seasonoftheyear
Environmentalinformation
Relatedtoenvironmentsurroundingssuchastemperature,airquality,moistureetc
Socialinformation
Relatedtosocialenvironmentsuchaswhoiswithyou,peoplenearby,whethertheuser
isinthemeetingorparty.
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31. Resourcethatarenearby
Relatestotheresourcesaccessiblenearbysuchasdevices,hostsorinformationsinks.
Availabilityofresources
Informationaboutthedeviceinusesuchasbatterypower,processingpower,displayetc
Physiologicalmeasurements
Relatestophysiologicalstateoftheusersuchasbloodpressure,heartrate,respirationrate
,toneofvoice
Activity
Relatestotheactivityoftheusersuchastalking,reading,walkingandrunning.
Schedulesandagendas
Relatestotheschedulesandagendasoftheuser. 31

32. Asystemiscontextawareofitcanextract,interpretandusecontextrelated
informationtoadaptitsfunctionalitytothecurrentcontext.
Threeaspectsofthecontextmanagement
Contextsensing
Thewayinwhichtheinformationisobtained
Contextrepresentation
Thewayinwhichthecontextinformationisstoredandtranscoded.
Contextinterpretation
Thewayinwhichthemeaningisobtainedfromthecontextrepresentation.
W3Cproposedastandardforcontextinformation,i.e.CompositeCapabilities/Preference
Profiles(CP/PP)
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33. Composite capabilities/ Preference
Profiles (CC/PP)
ProposedbyW3C
ModelisbasedonRDF(ResourceDescriptionFramework)and
canbeserializedusingXML.
Containsanumberofattributenamesandassociatedvalues
thatareusedbyanapplicationtodeterminetheappropriate
formaresourcetodelivertoaclient.
Helpaclient/proxytodescribetheircapabilitiestoanorigin
serverorothersenderofresourcedata.
Firdifferentapplicationtointeroperate,somecommon
vocabularyisneeded.
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34. Steps are
Devicesendsserializedprofilemodelwithrequestforcontent
OriginserverreceivesserializedRDFprofileandconvertsitinto
anin-memorymodel
Theprofilefortherequesteddocumentisretrievedandin-
memorymodeliscreated.
Thedeviceprofilemodelismatchedagainstthedocument
profilemodel
Asuitablerepresentationofthedocumentischosen.
Documentisreturnedtodeviceandpresented.
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35. The simplest use of CC/PP
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36. Policy Manager
Responsibleforcontrollingpoliciesrelatedtomobility
Apolicyissetofrules,theserulesneedtobefollowedunderdifferent
conditions.
Whenmobilityisconsidered,theinformationwillbevisiblefromoutsidethe
fourwallsoftheenterprise.
Organizationswillhavepoliciesregardingthedisclosureoftheinformation.
Eg:certaindocumentscanbeviewedonlyattheofficeofCEO
Thesekindsofpoliciesmustbetransferabletomobilecomputingpolicy
manager.
Itwillbeabletodefinepolicyforthedocumentsandassignrolestousers.
Eachrolewillhavepermission,prohibition,obligationsassociatedwithit.
Policymanagerwillhaverightstoread,writeandexecute
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37. Semantic Web
Howtomakemachinesunderstandpoliciesandmakethem
behaveintheexpectedfashion?
Semanticwebaddressesthisneed
Dataisdefinedinthewebandlinkedinsuchawaythatitcan
beusedbythemachinenotforjustdisplay,butforthe
automation.Security,filtering,integrationandreuseofdata
acrossvariousapplications.
ItisgenerallybuiltonsyntaxeswhichuseURLstorepresent
data,usuallytuplebasedstructures.
ThesesyntaxiscalledResourceDescriptionFramework(RDF)
syntaxes.
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38. Security manager
Providesaconnectionbetweentheclientdeviceandtheoriginserver.
Securitymanagerwillensuresecuritywithrespectto
Confidentiality:
Themessagetransactedneedstobeconfidential
Nobodyshouldbeabletoseeit.
Managedbyencryptioneg:AES
Integrity
Themessagetransactedneedstobetamper-resistant
Nobodyshouldbeabletochangeanypartofthemessage
Managedusingvarioushashingalgorithms
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39. Availability
Thesystemwillbeavailable
Nobodywillbeabletostoptheservice
Non-repudiation
Usersofthesystemcanbeidentified
Nobodyafterusingwillclaimotherwise
Managedbydigitalsignatures
Trust
Therearecomplexissuesofknowingwhatresources,servicesoragentsto
trust.
Thesystemwillbetrusted.
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40. Platform for privacy preference project
(P3P)
IsanemergingstandarddefinedbyW3C
Enableswebsitestoexpresstheirprivacypracticesinstandardized
formatsothattheycanberetrievedandinterpretedasuseragents.
WithP3P,usersneednotreadtheprivacypoliciestheyvisit
Insteadkeyinformationaboutthecontentofthewebisconveyedto
theuser
ThegoalofP3Pistoincreasetheusertrustandconfidenceinthe
web.
Thisinformstheprivacypoliciesaboutthesite,hencemakestheuser
todecidewhethertoreleasepersonalinformationornot.
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41. Adaptability Manager
Responsibleforadaptingcontent,behaviourandother
aspectsacc.tothecontextandpolicy
Maytakeanynumberofactionsdependingonthe
informationpassedtothecontextmanager
Mostcommonactionperformedistranscodingofthe
contentsothatitmaybeviewedonaparticulardevice
Appendinglocation-specificinformationtothedocument.
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42. Content adaption and transcoding
Contentadaptationcanbedoneateithercontentlevelinserverend
ortheagentlevelinclientdevice
Canbedoneinintermediatelevelinamiddlewareframework.
Contentadaptationneedstoconsiderthefollowingattributes:
Physicalcapabilitiesofthedevice
Screensize,widthandheightinpixels,color
Logicalcapabilitiesofthedevice
Displayimage,audio,video
Effectivenetworkbandwidth
Payload
Thetotalamountofbitscanbedeliveredtotheagentforstaticparts.
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43. Types of transcoding
Spatial
Transcodinginspaceordimension
Astandardframeisdownscaledandreduced.
Theframeischangedfromonesizetodifferentsizetosuitthetargetdevice
Temporal
Reductionofnumberofframesontimescale
Downscalestheno.oftransferredframestosuitthetargetdeviceand
networkbandwidth
Code
Usedtochangethecodingstandardfromonetoanother
Eg:transcodingBMPcodeintoWBMPforwirelessdevices
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44. Types of transcoding
Color
Requestedformonochromeclients
Useslesspixelsandreducesbandwidthconsumption
Modifiestheperceptionoftheimage
Objectorsemantic
Comprisesvarioustechniquesbasedonthecomputervision
techniques
Extractsthevaluableobjectfromthescene,transferthemwith
loweramountofcompressioninordertomaintainthebothdetails
andspeed.
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45. Serversideadaptation,resourcerequirementsare
Staticcontentsizeinbits
Displaysizesuchasheight,widthandarea
Streamingbit-rate
Colorrequirements
Compressionformat
Hardwarerequirementsuchasdisplayforimages,supportfor
audioandvideo
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46. Transcoding done through middleware
Benefitofthemiddlewareapproachisitistotally
transparenttothedeviceandcontent
Drawbackis
Contentprovidershavenocontroloverhowtheircontentwill
appeartodifferentclients
Theremaybelegalissueslikecopyright
Htmltagsprovidesformattinginformationratherthansemantic
information
Transcodingofvideosandaudioisnoteasy
Developingageneralpurposetranscodingengineisverydifficult.
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47. Content Rating and Filtering
W3ChasproposedastandardcalledPICS(PlatformforInternetContentSelection)
forratingofthewebcontent
Filteringofthecontenttakesplacebasedonthisrating
Itissetoftechnicalspecificationsforlabelsthathelpsoftwareandratingtowork
together
Ratingisallowedtotheserviceprovider,sinceitinvolvessomeamountof
subjectivejudgement
Ratingcanbethroughselflabellingorthirdpartlabellingofthecontent
PICSwasconcernedaboutchildrenaccessingtheinappropriatematerials,i.emeta
datasystem,meaningthatlabelsprovideanykindofdescriptiveinformationabout
internetmaterial
Controllingwasdoneusing:
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48. DigitalSignature:
Couplingtheabilitytomakeassertionswithcryptographicsignatureblockthatensure
integrityandauthenticity
IntellectualPropertyRightManagement
Usingthemeta-datasystemtolabelWebresourceswithrespecttoauthors,owners,rights
managementinformation
Privacy(P3)
UsingMeta-Datasystemtoallowsitestomakeassertionsabouttheirprivacypracticesand
foruserstoexpresstheirpreferencesforthetypeofinteractiontheywanttohavewith
thosesites.
Personalization
Basedonsomepolicy,thecontentcanbepersonalizedtosuittheneedofuserandthe
service
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49. Content Aggregation
Fourparties
EndUser(EU)
ContentProvider(CP)
ContentAggregator(CA)
InternetServiceProvider(ISP)/WirelessNetworkOperator(NO)
NOwillhaverouters,gateways,cacheetctoofferservice
Anynodecanberesponderandrequester
Therewillbedifferentparameterstodeterminethecontent
Theycanbestaticordynamicparameters
Staticparameterisreceivedbeforetheservicebegins
Dynamicparameterarethosewhicharerequiredwitheveryrequest.
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50. Types of service (Content Aggregator ‘s
perspective)
SingleServiceRequest
Worksatuserlevel
Worksforonlyoneuser
Groupservicerequest
Worksforgroupofusers
InitiatedatCAlevelortheNOlevel
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51. Seamless Communication
Asystemshouldbeavailableandaccessiblefromanywhereand
anytimeandthroughanynetworkordevice
Theusershouldbeabletoaccessthesystemwhentravelling.
Patienttravellingfromhousetohospitalviaambulanceor
helicopter,hereinformationhastoexchangewithoutany
interruptions.
SeamlessCommunicationwillcombineseamlesshandoffsand
seamlessroaming
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52. Handoffistheprocesswhichtheconnectiontothe
networkismovedfromonebasestationtoanotherbase
stationwithinthesamenetwork
Roamingisaprocessinwhichconnectiontothenetwork
ismovedfromonebasestationofonenetworktoanother
basestationofanotherbasestation.
Offersfreedomtoroamacrossdifferentwirelessnetworks
RoamingworkswithinhomogeneousnetworkslikeGSMto
GSMorCDMA2000toCDMA2000
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53. Followingaspectsneedstobemaintainedinseamless
communication
Authenticationacrossnetworkboundaries
Authorizationacrossnetworkboundaries
Billingandchargingthedatacollection
Endtoenddatasecurityacrossroaming
Handoffbetweenwirelessaccesspoints
Roamingbetweenthenetworks
Sessionmigration
IPmobility
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54. Autonomous Computing
Thepurposeofautonomoussystemistofreeusersandsystem
administratorsfromthedetailsofthesystemoperationandmaintenance
complexity.
Systemwillrun24X7
Combinationofthefollowingfunctions
SelfConfigurable
Willconfigureautomaticallyinaccordancewithhighlevelpolicies
Selfoptimizing
Continuouslylookforwaystoimproveitsoperationwithrespecttocost,resource
andperformance
SelfHealing
Willdetect,diagnoseandrepairlocalizedproblemsresultingfrombugsorfailures.
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55. SelfProtecting
Itwillbewelldefinedfromexternalattacks
Willnotcascadefailurestootherpartsofthesystem
SelfUpgradeable
Willbeabletogrowandupgradeitselfwithinthecontrolofthe
aboveproperties.
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56. Context aware Systems
Contextmanageristomaintaininformationpertainingtolocation,
mobiledevices,networks,users,theenvironmentaroundeach
mobiledeviceandothercontextinformationdeemedrelevant
Informationsuchas
Locationinformation
Helpstoidentifythelocationoftheuser/device
Canbeachievedusingdeviceorthroughnetwork
Fromdevice-GPS,canofferlocationprecisionof10feetradius
Fromnetwork-timingadvancedtechnology-precisionof100feetradius
Deviceinformation
Theknowaboutthecharacteristicsofthedevice
Todeterminetheresourcecapabilityandtheuserinterfacecapability
User-AgentparameterofHTTPwecanobtainthedeviceinformation
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57. Networkinformation
Mobilecomputingenvironment,devicemovesfromonenetworktoanothernetwork
Isrequiredtoidentifythecapabilityofthenetwork
Includesinformationsuchassecurityinfrastructure,servicesofferedbythenetworks
Userinformation
Thisinformationisrequiredtoidentifytheusercorrectly
Thesystemneedstoensurethattheuserisgenuineandwhoheclaimstobe
Informationcanbevalidatedthroughauthenticationindependentofdeviceornetwork
Environmentinformation
Tellsaboutthesurroundingenvironment
Knowaboutthetemperature,elevation,moistureetcwhichismainlyrequiredforsensor
basednetworks 57

58. GPS
GlobalPositioningSystem,isasystemthatgivesexactpositiononthisearth
FundedandcontrolledbyUSDepartmentofDefence
GPSsatellitesareorbitingaroundtheearth,whichtransmitsthesignalsthatcanbedetectedby
anyonewithaGPSreceiver
Hasthreeparts
Spacesegment
Usersegment
Controlsegment
SpaceSegment
Consists24satellites,eachinitsownorbit
EachGPSsatellitetakes12hourstoorbittheearth
Eachsatelliteisequippedwithaclocktobroadcastsignalswithrespecttotime
Usersegment
Hasreceivers,whichcanbeusershand,embeddedinamobiledeviceormountedinavehicle.
Receivesthesignalfromsatelliteatthespeedoflight
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