Technological Solutions to Support Mobile Web 2.0 Services · new friends (e.g., Facebook, MySpace, Friendster). TheBlogging services allow a user to create and manage a blog, that

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Chapter 5

Technological Solutions to Support Mobile Web 2.0 Services

Claudia Canali, Michele Colajanni, and Riccardo Lancellotti

Contents5.1 Introduction...............................................................................................965.2 MobileWeb2.0Services............................................................................97

5.2.1 SharingServices..............................................................................985.2.2 SocialServices.................................................................................995.2.3 LocationServices............................................................................99

5.3 FunctionstoSupportMobileWeb2.0Services........................................1005.3.1 FunctionsDescription..................................................................1005.3.2 ServicesandFunctions..................................................................1015.3.3 MobileDeviceLimitations...........................................................102

5.4 TechnologicalSolutionsforFunctionImplementation.............................1035.4.1 InformationInput.........................................................................1035.4.2 LargeFileUpload.........................................................................1055.4.3 Personalization..............................................................................1065.4.4 FruitionofMultimediaContent...................................................108

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96 ◾ Mobile Web 2.0

ThewidespreaddiffusionandtechnologicalimprovementsofwirelessnetworksandportabledevicesarefacilitatingmobileaccesstotheWebandWeb2.0services.TheemergingMobileWeb2.0scenariostillrequiresappropriatesolutionstoguar-anteeuserinteractionsthatarecomparablewithpresentlevelsofservices.Inthischapter,weclassifythemostimportantservicesforMobileWeb2.0andweiden-tifythekeyfunctionsthatarerequiredtosupporteachcategoryofMobileWeb2.0services.Wediscusssomepossibletechnologicalsolutionstoimplementthesefunctionsattheclientandattheserverlevel,andweidentifysomeresearchissuesthatarestillopen.

5.1 IntroductionTheso-calledMobileWeb2.0originatesfromtheconjunctionoftheWeb2.0servicesandtheproliferationofWeb-enabledmobiledevices.

ThetermWeb2.0,firstintroducedin2004–2005[20],indicatesanevolutionof the World Wide Web that aims to facilitate interactive information sharing,interoperability,user-centereddesign,andcollaborationamongusers.Althoughitisdifficult topreciselyconfineWeb2.0, itsnovelessencerefers toauser-centricenvironmentthatischaracterizedbytwopredominantfeatures[13]:

◾ Usersmayactivelycreateanduploadcontentsinmanyformsandhaveprom-inentprofilepages,includingheterogeneousinformation.

◾ Usersmaybelongtoasortofvirtualcommunitydeterminedbysocialinter-actions. For example, users may form connections among each other viaexplicitlinkstouserswhoaredenotedas“friends”orthrough“membership”groupsofheterogeneousnature.

Inthelastyears,wehavealsoobservedsignificanttechnologicalimprovementsinwirelessnetworksandthediffusionofmorepowerfulmobiledeviceswithincreasedhardwareandsoftwarecapabilities.Thegrowthandpenetrationofmobilecommu-nicationtechnologies,withanexpectednumberofglobalmobilephonesubscribersreachingupto4.5billionin2012[19],hasdeterminedascenariowhereuserscanaccess the Web directly from their mobile devices, and this trend is increasing.Mobiledevices,which forportability reasonsarecompanions in theuser’sdailylife,arelikelytobecomethefavoriteplatformtoconnect,interact,andsharecontentwithotherpeople.

5.4.5 Location-RelatedFunctions.......................................................... 1115.4.5.1 ComputationofDeviceLocation................................... 1115.4.5.2 Geo-ReferencedInformationManagement....................112

5.5 Conclusions..............................................................................................113References.........................................................................................................113

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Technological Solutions to Support Mobile Web 2.0 Services ◾ 97

The conjunction of Web 2.0 and mobile Web accesses is leading to a newcommunicationparadigm,wheremobiledevicesactnotonlyasmereconsumersofinformation,butalsoascomplexcarriersforgettingandprovidinginformation,andasplatformsfornovelservices[28].

WemayexpectthatinthenearfuturethedemandforWeb2.0serviceswillmainlycomefrommobiledevices[4,22].Thisexpectationisconfirmedbythecur-renttrendofpopularWeb2.0sites,suchasMySpaceandFacebook,whichoffermobileaccesstotheusersthroughspecificapplicationspreloadedonmobiledevices.Accordingtospecializedstudies,themostpopularWeb2.0sitesareexpectedtohaveamobilecomponentwithinafewyears[4].

MobileWeb2.0 representsbothanopportunity forcreatingnovel services(typically related to user location) and an extension of Web 2.0 applications tomobiledevices.Themanagementofuser-generatedcontent,ofcontentpersonaliza-tion,ofcommunityandinformationsharingismuchmorechallenginginacontextcharacterized by devices with limited capabilities in terms of display, computa-tionalpower,storage,andconnectivity.Furthermore,novelservicesrequiresupportforreal-timedeterminationandcommunicationoftheuserposition.Thechoiceofappropriate technological solutions that can effectively supportMobileWeb2.0serviceswillbeakeyelementtodetermineitssuccess[17].

In this chapter, we propose a classification of Mobile Web 2.0 services andweevidencesomekeyfunctions thatarerequiredfor their support.Weidentifythemainrequirementsfortheimplementationofeachfunction.Finally,wedis-cusspossibletechnologicalsolutionsforfunctionsimplementationattheclientandserverlevel,andidentifysomeopenissues.

This chapter is organized as follows. Section 5.2 proposes a classification oftheemergingservicesforMobileWeb2.0.Section5.3identifiesthekeyfunctionsrequiredtosupporttheMobileWeb2.0services.Section5.4describessometech-nological solutions to implement the supporting functions and identify possibleopenissues.Section5.5concludeswithsomefinalremarks.

5.2 Mobile Web 2.0 ServicesMobileWeb2.0includesawiderangeofheterogeneousandcomplexservices.Inthissection,weproposeatwo-levelclassificationoftheseservicesbasedonwhatweconsidertheirpredominantfeatureandothermorespecificcharacteristics.InthetaxonomyshowninFigure5.1,atthefirstlevelwehave

◾ Sharing services that are characterizedby thepublicationof contents tobesharedwithotherusers

◾ Social servicesthatrefertothemanagementofsocialrelationshipsamongtheusers◾ Location servicesthattailorinformationandcontentsonthebasisoftheuser

location

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Asindicatedbythedottedboxesinthefigure,thesharingandsocialserviceclassesrepresentextensionsofexistingWeb2.0tothemobilescenario,whilethelocationservicesrepresentacompletelynovelclassofservices,thatexploitsinformationontheusermobility.

ItisworthnotingthattheserviceclassesshowninFigure5.1aswellastheirsubclasses,describedbelow,arenotcompletelydisjointedcategories.

5.2.1 Sharing ServicesSharingservicesoffertheusersthecapabilitytostore,organize,search,andman-ageheterogeneouscontents.Thesecontentsmayberated,commented,tagged,andsharedwithspecifiedusersorgroupsthatcanusuallyvisualizethestoredresourceschronologically,bycategory,ratingortags,orviaasearchengine.

Thesubclassofmultimediasharingconsidersmanagementservicesrelatedtomultimediaresources,suchasphotosorvideos.Theseresourcesaretypicallygener-atedbytheusersthatexploitthesharingservicetouploadandpublishtheirowncontents.PopularexamplesofWebportalsofferingamultimediasharingserviceincludeFlickr,Zooomr,YouTube,Mocospace,andMobimii.

Theclassofbookmarksharingservicesallowsuserstomanageacommoncol-lectionofWebpagebookmarks.Inthiscase,thesharedcontentsarepubliclyavail-able links toWebpages thatusersconsideras interesting resourcesandwant tosharewithotherusers.Manybookmarking servicesprovideWeb feeds for theirlistsofbookmarks, so that subscribersmaybecomeawareofnewbookmarksastheyaresharedandtaggedbyotherusers.AmongthemostpopularportalsthatofferbookmarksharingservicesweciteDel.icio.us,Reddit,DigganditsrecentlydevelopedmobileversioncalledDgm8.

Mobile Web 2.0services

Locationservices

Blogging

Multimediasharing

Bookmarksharing

Peoplediscovery

Communitymanagement

Microblogging

Point of interestdiscovery

Socialservices

Sharingservices

NovelExtensions

Figure 5.1 AQ1

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5.2.2 Social ServicesThemanagementofuserrelationshipsisthemainfeatureofthesocialservicesthatallow users to create social connections based on common interests, hobbies orexperiences,andtoactivelyinteractwitheachother.

TheservicesbelongingtotheCommunity managementsubclassallowregistereduserstomaintainalistofcontactdetailsofpeopletheyknow.Theirkeyfeatureisthepossibilitytocreateandupdateapersonalprofileincludinginformationsuchasuserpreferencesandhislistsofcontacts.Thesecontactsmaybeusedindifferentwaysdependingonthepurposeoftheservice,whichmayrangefromthecreationofapersonalnetworkofbusinessandprofessionalcontacts(e.g.,Linkedln),tothemanagementofsocialevents(e.g.,Meetup),anduptotheconnectionwitholdandnewfriends(e.g.,Facebook,MySpace,Friendster).

TheBloggingservicesallowausertocreateandmanageablog,thatis,asortofpersonalonline journal,possibly focusedona specific topicof interest.Blogsareusuallycreatedandmanagedbyan individualora limitedgroupofpeople,namely author(s), through regular entries of heterogeneous content, includingtext,images,andlinkstootherresourcesrelatedtothemaintopic,suchasotherblogs,Webpages,ormultimediacontents.Ablogisnotasimpleonlinejournal,becausethe largemajorityof themallowexternalcommentsontheentries.Thefinaleffect is thecreationofadiscussion forumthatengagesreadersandbuildsa social community aroundapersonor a topic.Other related servicesmayalsoincludeblogrolls(i.e.,linkstootherblogsthattheauthorreads)toindicatesocialrelationshipstootherbloggers.AmongthemostpopularportalsthatallowuserstomanagetheirownblogweciteBlogSpot,LiveJournal,Wordpress,andSplinder.

In Microblogging services, the communication is characterized by very shortmessageexchangesamongtheusers.Althoughthisclassofservicesoriginatesfromthebloggingcategory,thereareimportantdifferencesbetweenmicrobloggingandtraditional blogs: (1) the size of the exchangedmessages is significantly smaller,(2) thepurposeofmicroblogging is to capture and communicate instantaneousthoughtsorfeelingoftheusers,and(3)therecipientofthecommunicationmaydifferfromthatoftraditionalblogsbecausemicrobloggingallowsauthorstointer-actwithagroupofselectedfriends.Twitter,Jaiku,Plurk,Folkstr,GUSHUP,andMobikadeareexamplesofportalsprovidingmicrobloggingservices.

5.2.3 Location ServicesTheabilitytocontinuouslytraceuserpositionrepresentsoneofthemostinnovativefeaturesinthecontextofMobileWeb2.0,whichemphasizestheimportantroleofmobiledevicesinaccessingtheWeb[26,31].

Theknowledgeoftheusercurrentlocationmaybeexploitedinseveralwaystooffervalueaddedservices.Oneofthemostpopularusesconcernspeople discovery,thatbasicallyaimstolocateuserfriends;significantexamplesofthisservicemaybe

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foundinLoopt,Brightkite,andBuddyBeaconapplications.Usuallytheseservices,alsocalled“friendfinder”applications,plotthepositionoftheuserandhisfriendsonamap;thegeographicallocationoftheusersisuploadedtothesystembymeansofapositioningsysteminstalledontheusermobiledevices.

Anotherclassoflocationservices,thatwecallpoints of interest (POIs) discovery,exploitsgeographicalinformationtolocatePOIs,suchasevents,restaurants,muse-ums,andanykindofattractionsthatmaybeusefulorinterestingforauser.TheseservicesoffertheusersalistofnearbyPOIsselectedonthebasisoftheirpersonalpreferencesandspecifications.POIsarecollectedbyexploitingcollaborativerec-ommendations fromotherusers thatmayaddanewPOIbyuploading itsgeo-graphicallocation,possiblydeterminedthroughaGPSpositioningsysteminstalledonthemobiledevice.Usersmayalsouploadshortdescriptions,comments,tags,andimagesorvideosdepictingtheplace.POIdiscoveryservicesareprovidedbyPOIfriends,Socialight,andMobnotesportals.

5.3 Functions to Support Mobile Web 2.0 ServicesTheprevioussectionhaspointedoutthatMobileWeb2.0includescomplexandheterogeneousservices,sometotallynew,othersasextensionsofexistingWeb2.0services. In this section,we identify somekey functions that are at thebasis ofMobileWeb2.0servicesbyseparatingfunctionsthatarerequiredtoextendWeb2.0servicestoamobilecontextfromfunctionsthatarespecificallyrelatedtothenovelclassoflocationservices.

AmongthefunctionsrequiredtoextendWeb2.0servicestoamobilescenario,weidentify

◾ Informationinput◾ Largefileupload◾ Personalization◾ Fruitionofmultimediacontent

Otherfunctionsthatarerelatedtothepossibilityoflocalizingthemobiledeviceare

◾ Computationofdevicelocation◾ Geo-referencedinformationmanagement

5.3.1 Functions DescriptionWegiveabriefdescriptionforeachoftheabovefunctionstosupportMobileWeb2.0services.

The information inputfunctionreferstothecommunicationofsmallsizedata,typicallyinatextformat,fromtheuserstotheservicethroughamobiledevice.

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Insertingcommentsinablogorinaforum,taggingaresource,assigningratings,updatingpersonalinformationorsimplyaddinganewentryinamicrobloggingservice represent typical examples of information input. These operations occurveryfrequentlyintheMobileWeb2.0scenario,whereusersarenotonlyconsumersbutalsoprovidersofinformationthatactivelyinteractwiththeservices.

Thelarge file uploadfunctionsharesseveralcommontraitswiththeinforma-tioninputfunction;however,thefocusismainlyrelatedtomultimediaresources,insteadoftextualinformation.Theuploadofuser-generatedlargemultimediafiles(e.g.,images,audio,andvideoresources)isacharacteristicfeatureofMobileWeb2.0servicesthathasbeeninheritedbyWeb2.0,andisbecomingincreasinglypop-ularthankstothediffusionofmobiledevicesequippedwithbuilt-incameras.

Thepersonalizationfunctionaimstotailorcontentstotheuserpreferencesandneeds [18]. Information about the users is collectedby the services andmaybeexploitedtoofferpersonalizedcontentinseveralways,forexample,throughcus-tomized layout, information filtering, recommendation systems, subscription tospecificchannelsornewsfeeds,andspecificationoflistsofcontacts.

Another feature ofMobileWeb2.0 that comes from Web 2.0 concerns thefruition of multimedia contents,whichrefers to thehighdemandformultimediaresources,suchasimages,video,andaudio.Besidesmultimediasharingservices,also blogs, community management or POI discovery involve a considerableexchangeofmultimediacontentsamongmobileusers.

ThelasttwofunctionsrefertothemostinnovativefeatureofMobileWeb2.0services,thatis,thecapabilityofidentifyingthecurrentlocationofamobiledevice.Thegeographicalinformationmaybeexploitedbytheservicestolocateauserorasuggestedpointofinterest.Thecomputation of device locationfunctionisrequiredtoidentifythegeographicalpositionofthemobiledevice.Oncecomputed,theloca-tiondatashouldbecommunicatedtotheserviceandstoredasageo-referenceddata.Theoperationsrelatedtothestorageandmanagementofthisdataareaccomplishedbythegeo-referenced information managementfunction.Itisworthtorecallthatalocationdatamayreferbothtoapointofinterestandtoauser.Ifreferredtoauser,thecurrentlocationmayrepresentavolatiledatathatissubjecttofrequentupdates.

5.3.2 Services and FunctionsEachMobileWeb2.0servicerequiresthesupportofatleastoneoftheabovefunc-tions.InTable5.1,wemapthefunctionsandtheserviceclasses:eachfunctionisconsideredmandatory (Yes),not required (No)oroptional (Maybe) fora specificserviceclass.Wedonotincludeinthetablethetwofunctionsrelatedtothelocal-izationofmobiledevicesbecausetheirmappingontheservicesisquitestraightfor-wardandmayeasilybesummarizedasfollows:computationofdevicelocationandgeo-referencedinformationmanagementaremandatoryonlyforlocationservices,butoptionalforallotherservices,wheregeo-referenceddatamayrepresentanaddi-tionalinformationaboutusersanduploadedcontents.

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Weobservethatsomeinputfunctionisrequiredbyalltheservicesthroughoneormoreoperations,suchaspostingcomments,addingratingsortaggingresources.Theuploadfunctionismandatoryformultimediasharingservices,wheretheusersupload self-generated large sizefiles andwherepictures takenon-the-flymaybeaddedtoenrichtheshortpostsoftheprovidedPOIdescription;theuploadfunc-tionisoptionalinmicrobloggingandPOIdiscoveryservices.Thepersonalizationfunctionisoptionalforbookmarksharingandbloggingservices,whereitmaybeexploitedtofiltercontentsandsubscribetonewsfeeds,whileismandatoryforalltheotherservicesthatstronglyrelyonpersonalinformationmaintainedintheuserprofiles.

Althoughmultimediafruitiondoesnotrepresentacharacterizingfeature,itismandatoryinmultimediasharingservices,whileoptionalforcommunityman-agement,duetothenatureoftheexchangedcontents,suchasblogging,microb-logging,andPOIdiscoveryservices,wherethepresenceofmultimediacontentsispossible.

5.3.3 Mobile Device LimitationsSupportingthepreviouslydescribedfunctionsinamobilescenarioisnottrivialduetothelimitedcapabilitiesofmobiledevicesintermsofconnection,CPU/storagecapabilities,displaysize,andinterfaceusability.

Thebandwidthavailabletomobiledeviceshasbeengreatlyincreasedwiththediffu-sionof3-Gwirelessnetworks,andfurtherenhancementsareexpectedwiththeadventof4-Gtechnologies[11].However,thewirelessnetworkconnectionremainsrelativelyunstableandheterogeneous,becauseitisaffectedbycoverageissues.

AQ2

AQ3

Table 5.1 Functions to Support Mobile Web 2.0 Services

Mobile Web 2.0 Service

Functions

Input Upload PersonalizationMultimedia

Fruition

Multimedia sharing Yes Yes Yes Yes

Bookmark sharing Yes No Maybe No

Community management

Yes No Yes Maybe

Blogging Yes No Maybe Maybe

Microblogging Yes Maybe Yes Maybe

People discovery Yes No Yes No

POI discovery Yes Maybe Yes Maybe

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Thecomputationalpowerandstoragecapacitieshaveexperienced significantimprovements in mobile devices; however, they remain significantly lower thanthoseofalaptop/desktopthatistypicallyusedtoaccessWeb2.0services.Thecom-putationalpowerandstoragecapacitymayintroduceproblemswhenthemobiledevicemusthandlecomplexormultimedia-richservices,preventingthefruitionandthestorageofsomekindsofresourceformats[12].Furthermore,computation-allyexpensivefunctionsconsumeasignificantamountofenergy,thusaffectingthelifetimeofbatteries.

The display is characterized by minor improvements because of an intrinsicconstraintofportabilityofthemobiledevices.Evenifthetrendistowarddeviceswith at least3 inches screens and resolutionsof480×320pixels [32], the lim-iteddisplaysizemakesforveryunpleasantusernavigationwhileaccessingservicesdesignedfordesktopcomputers.Finally,thedeviceinterfaces,whichforceuserstoinsert inputdatathroughtinykeypadsorsmallon-screenkeyboards,arehardlysatisfactoryfortheuserswhoactivelyinteractwiththeservice.

Even if the technological evolution has substantially improved the scenarioof the mobile devices population [28,32], the above limitations may hinder thedeploymentofthekeyfunctionsrequiredforMobileWeb2.0services.InSection5.4,wedescribesometechnologicalsolutionsthatmaybeexploitedtoimplementthefunctionstosupportMobileWeb2.0services,anticipatingthattheimplemen-tationofsomefunctionspresentsopenissuesthatdeservefurtherresearchefforts.

5.4 Technological Solutions for Function Implementation

ThemainfunctionstosupportMobileWeb2.0services(informationinput,largefileupload,personalization,fruitionofmultimediacontents,andlocation-relatedfunc-tions)maybeimplementedthroughdifferenttechnologicalsolutions.Eachsolutionmayfollowaclient-sideorserver-sideapproachdependingonwherethefunctionsareimplemented.Thebestapproachisnotanabsolutechoice,butitstronglydependsonthespecificcontextofeachservice,asdiscussedintherestofthissection.Wecananticipatethatsolutionsfollowingaserver-sideapproachmayrelyonmorepowerfulplatformsandusuallydonotpresentsevereissues.However,intheMobileWeb2.0contextmanyfunctionsnecessarilyhavetobeimplementedontheclientside,evenifthismeanscopingwiththelimitationsofthemobiledevices.

5.4.1 Information InputWhentheinformationinputiscarriedoutthroughamobiledevice,thepresenceofintermittentorlowbandwidthconnections,aswellasthesmalldisplayandthepeculiar inputmethodsof thesedevices, introducenovelchallenges thatarenotpresent in Web 2.0. For example, network connection quality can lead to poor

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navigationexperiencebecausetaskssuchaspagerefreshmaybeveryslowwithanunreliable and limited wireless connection. Furthermore, typing input informa-tionrepresentsacumbersometaskinmostmobiledevicesbecausetheusermustrelyonastylusormustinteractwithsmallon-screenkeyboards.Theselimitationsmayresultinanunsatisfactoryexperiencethatcouldmoveawayusersfromtheseservices. Allowing a comfortable navigation and supporting information inputthroughamobiledeviceisakeyissueinthecontextofMobileWeb2.0,becausethisfunctionisafundamentalelementforalltheofferedservices.

Theproblemofmanaginguser input isusuallyaddressedbyclient-sidesolu-tionsandrequiresoperatingontwodistinctelements:first,thecommunicationsbetweenmobiledevicesandserversshouldbeoptimizedtoreducetheneedfor(synchronous)dataexchange;second,theinterfaceoftheserviceshouldberede-signedtoallowcomfortableusernavigationandinputoperationsinamobiledevice.

Tocopewiththefirstproblem,thetypicalsolutionistoadoptasynchronouscommunicationsbetweentheclientandtheserver.Thissolutionallowsthebrowseronthemobiledevicetocommunicatewiththeserverinthebackgroundinanasyn-chronouswaywithrespecttotheuserinteractionsandwithoutinterferingwiththecurrentstateofthepage.TheresponsesfromtheserverarehandledasynchronouslybythebrowserthatupdatestheWebpageswithouthavingtokeeptheuseratten-tion frozen. This benefit is particularly valuable in a mobile context, where theinteractionwiththeserviceoccurswhiletheuserisontherunandcannotstaycon-tinuouslyfocusedonthedevice.BysendingrequestsjustfortherequireddatathattypicallyrepresentjustasmallportionoftheinformationmanagedbythewholeWebpage,asynchronouscommunicationsbetweentheclientandtheserverallowstogreatlyreducetheamountofreloadinganddatatransferred.Furthermore,thesolutionallowsimprovingtheuserinputspeedandreducesthedisplayprocessingrequirements.

Typical examplesof technologies supporting this approach areAsynchronousJavaScriptandXML(AJAX)andFlex.AJAXisconsideredoneofthemostimpor-tantenablingtechnologiesforimplementinginteractiveservices.Actually,thetermAJAXindicatesamixtureofseveraltechnologiesthatintegrateWebpagepresen-tation,interactivedataexchangebetweenclientandserver,client-sidescripts,andasynchronousupdatesofserverresponse[24].FlexisanevolutionofthewidespreadFlashtechnologycommonlyusedtocreateanimation,advertisements,andtointe-gratevideointoWebpages.FlexobjectsofferfunctionalitiesthatresembletheAJAXapproach,allowingthedeploymentofservicesthatexploitasynchronouscommuni-cationwiththeservertoimprovetheuserexperienceintheMobileWeb2.0scenario.

A limitation for asynchronouscommunications at theWeb level in this sce-narioisthatnotallmobileWebbrowserssupporttherequiredtechnologieswithadequateperformance.Whilethemostrecentmobiledevicessatisfythisrequire-ment,olderdeviceswithlesscomputationalpowerandmemorymaynotbesuitabletosupportasynchronouscommunicationwiththeserver.Anincreasinglypopularalternativeistoredesigntheinterfaceattheclientlevel,withoutneedtouseWeb

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browsers.Inthiscase,theserviceisprovideddirectlybyanapplicationinstalledinthemobiledevice,andinteractionwiththeserverismanagedasynchronously,pos-siblyusingthesameWebapplicationprogramminginterface(API)thatarealreadyavailableforinteractionthroughtheWebbrowser.Thisapproach,typicallyrelyingontheJavaplatformformobiledevicesorthroughsomedevicespecificsoftwaredevelopmentkit (SDK) (as in the caseof the iPhoneObjective-CAPI),has thepotentialtoreducethecomputationalandmemoryrequirementsthatmayhinderthepopularityofaserviceaccessedthroughaWebmobilebrowser.However,thisapproachrequiresasignificantamountofeffortforthedevelopmentoftheappli-cation.Furthermore,theclientapplicationsusuallyneedfrequentupdatesthatinmostcaseshavetobedonemanually.

Thesecondcriticalproblemisthedifficultyforuserstointeractwithuserinter-facesandtypedataforinputinamobiledevice.Theneedtorelyonstylusorthesmallsizeofon-screenkeyboardsinmobiledevicessuggestthat,evenifasynchro-nouscommunicationcanimprovetheuserexperience,inputoperationsremainakeyissueforthediffusionofMobileWeb2.0services.Theproblemofsupportingseamlessinputfromuserremainsanopenissuetoaddress,althoughsomepossibleresearchdirectionseemsmorematureandpromisingthanothers.

Afirstsolutionmaybetoredesigntheuserinterfacetoavoidinputwheneverpossible.Thetypicalapproachistorelyonfill-informsthatarepre-compiledbasedondefaultsettingsthatmaybepersonalizedforeachuser.Inthisway,theuserdoesnothavetocompileforms,butcansimplychoosebetweenoneormoreoptions.

Thealternative approach is to exploit client-side technologies to simplify theinputoperationbydefiningnovelinterfacesforhumanandcomputerinteraction.Tothisaim,speechrecognitionandusergesturesrecognition(basedonaccelerom-eters)aregainingpopularityinmobiledevices[28].ThemaindrawbacksofthissolutionarethedifficultytointegrateuserinteractioninaWeb-basedinterfaceandtheneedtoadaptthesesystemstomobiledevices.

Alternativesolutionsmaybetoocomputationallyexpensiveforcurrentmobiledevices.Forexample,speechrecognitionwithalargevocabularymaybecomputa-tionallyunfeasibleonCPU-powerconstraineddevices.Inasimilarway,accesstoaccelerometerforgesturerecognitionneedstobetailoredtoeveryspecificdevicecharacteristic,thushinderingtheadoptionofgeneralsolutions.Weexpectthatthisareaofalternativemethodsforhuman–computerinterfacewillreceivesignificantattention from researchers and industries, with the goal of simplifying the taskof informationinputfromtheuserthusenablingthedevelopmentofevenmoresophisticatedandinteractiveservices.

5.4.2 Large File UploadAsforinformationinput,thelimitationsofmobiledevicesmayrepresentanissuethathindersthepossibilityforuserstodirectlyuploadtheirself-generatedcontents,suchaspicturesandvideos.

AQ4

AQ5

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Theuser interface of amobile device is often inadequate to support largefileuploadstoMobileWeb2.0services.Forexample,uploadingapicturefromamobiledevicerequirestheoff-linecreationoftheresourcewiththebuilt-incamera,thetem-porarystorageofthemultimediadatainthedevicefilesystem,andfinallytoseekthesavedfilefromamongthedirectoriesfortheuploadoperation.WhilethisbehaviorisacceptablewhenworkingonaPCoralaptop,itbecomesunacceptablefortheusersofaMobileWeb2.0service.Auserinterfacethatsimplifiestheuploadofalargefileandespeciallymultimediacontent(forexample,throughaclick-and-uploadfeature)willplayakeyroleforthesuccessofMobileWeb2.0.

Theissuesrelatedtotheuploadoflargefilesaretypicallyaddressedattheclientside.Asolutionistoexploitspecializedclientsthatprovidedirectandeasyuploadofuser-generatedcontentswithouttheneedtorelyonWeb-baseduploadformsoronmultimediamessagingservice(MMS).Forexample,specializedclientapplicationsmayallowpicturesorvideostobetakendirectlythroughthedevicebuilt-incameraanduploadedwithasingleclick.ThissupporthasthepotentialtostronglyaffectthesuccessofMobileWeb2.0services.AclearconfirmationofthisclaimcanbefoundintherecentannouncementbyGoogle:dailyYouTubeuploadsdirectlyfrommobiledeviceshaveincreased400%in6daysafterthereleaseofthelastmodelofiPhone[30]thatprovidesuserswithaneasyinterfacetouploadvideostotheYouTubeportal.

Anothercriticalissueforuploadinglargefilesfromamobiledeviceisrelatedtothequalityofthewirelessconnection.Theuploadtimemayincreasetoanunacceptablelevel,and,inthecaseofdisconnections,uploadmayfail.Theexchangeoflargeamountofdatamayalsoreducethebattery lifetimeandlimitthepossibilityfortheusertointeractwiththeservice.Theproblemseemstobeevenmorecritical ifweconsiderthecurrenttrendofinstallinghighresolutioncamera(uptoseveralMpixelperimage)inmobiledevices.Toovercomethislimitation,itispossibletocarryoutsomecontentadaptationbeforetheupload.Forexample,imagescanbecroppedorscaleddirectlyonthemobiledevicetoreducetheamountofdatatransferredthroughthenetwork.

However, the actual effectiveness of these solutions remains an open problem.Indeed,thereisatrade-offinvolvingcomputationalpower,networkconnection,andbatterypower.Ononehand,contentadaptationonthedevicerequiresasignificantamountofcomputationalpowerthatmaynotbeavailableoneverydevice.Ontheother hand, transferring the high resolution resources without any adaptation totheserverconsumesnetworkresourcesthatinmobiledevicesmaybescarceaswell.Furthermore,bothCPU-intensiveoperationandwirelessdatatransferhaveasignifi-cantimpactonthemobiledevicebatteries.Theresearchforsolutionsthatcanaddressthistrade-off,forexample,combiningclient-sideandserver-sideadaptation,representsanopenissuethatislikelytoreceivegrowingamountofattentioninthenextyears.

5.4.3 PersonalizationThepersonalizationfunctionrequiresaninitialphaseofuserdatacollection,pos-siblyfromdifferentsources.Then,thegatheredinformationhastobestoredina

AQ6

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userprofileandmaintainedforsubsequentuse.Thecollectionandthemanagementoftheuserinformationaretypicallyaccomplishedthroughaserver-sideapproach.

Theuserinformationmaybeobtainedbasicallyfromtwosources:

◾ Explicitlycommunicatedbytheuser◾ Implicitlyacquiredfromtheuserbehavior

Inthecaseofexplicitcommunicationbytheuser,personalinformationarepro-videdthroughappositefill-informstoadd/edituserpreferences;thiscommunica-tionmayoccurwhentheuserregistershimselffortheaccesstoaserviceormaybefilled/modifiedlater.

When implicitlyacquired, theuser information is typically inferredthroughtheanalysisoftheuserbehavior,forexample,throughdataminingoperationsonaWebsitelogfilesoronsetsofreallysimplesyndication(RSS)feedstheusersub-scribedto[14].Collaborativefilteringtechniquesmayalsobeexploitedforgroupusersbasedonsimilarpreferencesorclickhistory[15]:missinginformationaboutausermaybeintegratedbyconsideringthecorrespondinginformationinthepro-fileofotherusersbelongingtothesamegroup.Thesetechniquesforimplicituserprofilingrepresentserver-sidesolutionsandareusuallycarriedoutoff-linebecausetheyinvolvetime-consumingoperations,suchasdatamining.

Theuserprofilesareusuallymaintainedindatabase(s)ontheserverinfrastruc-tures.WeshouldconsiderthattheinfrastructurestosupportMobileWeb2.0ser-vicestypicallyconsistofdistributedsystemswithmultipleservers,suchasContentDelivery Networks [5]. Solutions for replicating data storages on a distributedinfrastructurehavebeenwidelystudiedinthecontextofdatabases[21].

ThesimplestsolutiontomanagedatabasereplicationindistributedWebenvi-ronments isbasedonacentralizedmastercopyandreplicatedsecondarycopies.Incaseofupdates,dataaremodifiedonthemastercopyandthechangesarethenpropagatedtothesecondarycopies.However,theaccesspatternsfortheuserpro-filespresentauniquefeaturethatmayhelpthemanagementincaseofreplication.Specifically, eachuser typically interactswith only one server; hence theprofileofagivenuserisaccessedbyoneserverforthewholedurationofausersession.Thisaccesspatternhasasignificantimpactonconsistencyandreplicationpolicies.Indeed,thewholedatasetofuserprofilescanbepartitionedanddistributedovertheserversdependingontheuseraccesspatterns.Sincenoreplicationisneeded,consistencyissuesarelimitedtoguaranteethattheuserprofilesontheserversareconsistentwiththedataofthemastercopy.

Usermigrationamongmultipleservers,however,mayoccurbetweenconsecu-tivesessions.Therefore,theuserprofiledatashouldmigratefollowingtheuser.Thesupportforthisbehaviorisnotexplicitlyoptimizedinmostreplicationstrategiesforback-enddatabases.AnexampleofproposaltohandleprofilemigrationisTuxedo[25],agenericdatacachingframeworkthatsupportsusermobilitybyallowingdatatofollowtheuser.

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It isworth tonote thatauniqueopportunityofferedbyMobileWeb2.0concernstheuseofSubscriber Identity Module(SIM),removablecardsforperson-alizationpurposes.SIMcardshavealwaysbeenusedtostoredatasuchasinterna-tionalnumberofthemobileuser,billinginformation,securityauthenticationandcipheringdata,subscriberaddressbooks,etc.However,theadventofMobileWeb2.0hascreatedtheopportunitytoexploitSIMcardsasaplacetostoreuserauthentica-tiondataforpersonalizationpurposes.Thissolutionfollowsthephilosophyofa“uni-fiedlogin”thatallowsuserstologintomanyMobileWeb2.0servicesusingjustoneaccount,thatismaintainedbysimplymovingtheSIMcardfromdevicetodevice.

Thepossibilitytoexploitasortofunifiedloginisparticularlyimportanttopro-videuserswithcustomizedinformationcomingfromdifferentMobileWeb2.0ser-vices.AtypicalbehaviorofMobileWeb2.0users,indeed,istosubscribetoseveralservicesandprovidedifferentinformationtoeachofthem.Forexample,foreachserviceausermayspecifyalistofcontacts;tocommunicateorsharecontentswithallhiscontacts,theusershouldseparatelyaccessallthesubscribedservices.Mash-uptechnologiesareincreasinglybeingusedtoprovideuserswithupdatedinformationcoming from different subscribed services without the need of separately access-ingallofthem.Thetermmash-upindicatesanapproachthatallowseasyandfastserviceintegrationofdataandfunctionalitiesfromtwoormoreexternalsourcesbyusingpubliclyavailableAPIs.Thankstothiscontentaggregation,usersmayhaveavailableonasinglepageinformationcomingfromdifferentservicesandupdatedinrealtime.Furthermore,mash-upsolutionsalsoallowintegratingpersonalprofileinformationmaintainedbydifferentserviceswithoutduplicationoftheinformationitself,thussimplifyingupdateoperations.Architecturally,thecontentaggregationusuallytakesplaceontheclientside,byexploitingtheWebbrowserofthemobiledevicetocombineandreformatthedataretrievedfrommultipleservices.

5.4.4 Fruition of Multimedia ContentThepoorconnectionsofwirelessnetworksandthereducedhardwarecapabilitiesofmobiledevicesmaydeterminecriticalissuesforthefruitionofmultimediacontentssuchas(1)thelowandunreliablenetworkbandwidthmaycauselonglatencywhiledownloading multimedia resources, (2) the computational power may be insuf-ficienttodecodeandrenderhighqualitymultimediaresourcesand(3)thesmalldisplay sizemaynot supporthigh resolution formats.These limitationsgive risetotheneedforadaptingmultimediacontentstomatchthecapabilitiesofmobiledevicesandnetworkconnections.

Contentadaptationmayinvolveawiderangeofheterogeneoustransformationsthatareappliedtotheoriginalcontentstogenerateadaptedversionssuitabletobeconsumedbymobiledevice[9].Thebasicideabehindcontentadaptationisthatmobileusersoftendonotneedabest-qualityexperiencewhenconsumingmulti-mediaresources,butratheragood-enoughqualityandacceptablelatencytoconveytheneededinformation[34].

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Theadaptationistypicallyappliedtomultimediaresourceswiththemaingoalofreducingtheirsize.Sizereductionhelpstodecreasedownloadingtimeandstor-agerequirements,andmayalsoreduce,dependingonthetypeofadaptation,thecomputationaldemandtorendertheresourceonthemobiledevice.Alargeandheterogeneoussetof resourceattributescanbeconsidered foreachtypeofmul-timedia resource to perform the adaptation [9]. For example, image adaptationtypicallyincludesscaling,cropping,orcompressingtheimage;audioresourcesareadaptedbyreducingthebitrate[16];commontransformationsforvideoresourcesareframesizeandcolordepthreduction[16].

Theadaptationofmultimediacontentsmaybeperformedattheclientsideorattheserverside.

Acritical aspectof contentadaptation is thehighcomputational costof thetransformations,especiallywhenappliedtolarge-sizedmultimediaresources.Thecomputationalcostofcontentadaptationmayeasilyexacerbatethecapabilitiesofthesupportinginfrastructures[7];forthisreason,determiningtheplatformwherecontentadaptationshouldbecarriedoutrepresentsastrategicchoice.

Inaclient-sideapproach,contentsareadapteddirectlyonthemobiledevice.Theadvantageofthissolutionisthattheadaptationmaygeneratearesourcever-sionthatperfectlymatchesthedevicelimitations,thankstotheexactknowledgethatthedevicehasofitscapabilities.However,thisapproachisnotalwaysfeasibleorconvenientdue to thedevice limitations.Thereducedstorage,computationalpower,andbatteryenergymaypreventperforminglocallytheexpensiveadapta-tiontasks.Furthermore,aclient-sidesolutiondoesnotaddress the issueofpoorconnections:sincethemultimediaresourceshavetobeentirelydownloadedonthemobiledevice,longlatencymaybeexperiencedwhiletransmittingthecontentoverthewirelessconnection.Hence,wemayobservethat,even ifmobiledevicesarebecomingmorepowerfulplatformswithmedium-largeconnections,theirlimita-tionsstillpreventrelyingonlyonclient-sideadaptations.Thetechnologicalevolu-tion,however,allowsthemobiledevicestoconsumelargersizeandbetterqualityresourceswithrespecttothepastand,ifnecessary,tocarryoutlocallysomefinaladjustmentsonmultimediacontents.

Theserver-sideapproachrepresentsamorefeasiblesolutionwherethecontentadaptationiscarriedoutontheserver infrastructure.Inthiscase, therearetwomainalternativesaboutwhenmultimediaresourcesshouldbeadapted:on-the-flyandoff-lineadaptation.

If on-the-fly adaptation is applied, the server infrastructure generates anadaptedresourceversionforthespecificmobiledeviceatthemomentoftherequest.However,thehighcomputationalcostsofadaptationmayhindertheeffectivenessof this solution in the Mobile Web 2.0 scenario. Solutions based on on-the-flyadaptationhavebeenproposed in thepast [27],usually integratedwithcachingstrategiesattheintermediarylevel[3,10].However,thisapproachwasfeasibleinacontextcharacterizedbyalimitedamountofavailablemultimediaresourcesandasmallfractionofrequestscomingfrommobiledevicesand,consequently,requiring

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adaptation. On the other hand, an on-the-fly approach may lead to excessivecomputationalcostsfortheserverplatformsintheMobileWeb2.0scenario,evenifcoupledwithcachingstrategies.

Theoff-line approachconsists inpre-generatingmultiple adaptedversionsofmultimediacontentsthataremaintainedontheserverinfrastructureorcachedatanintermediarylevelandthendeliveredtotheuserwhenrequested.Relyingcom-pletelyonoff-lineadaptationmeanstopre-generateadaptedversionsofallmulti-mediaresourcesforanyclassofdevice/connection,thusavoidingtheexpensivecostofon-the-flyadaptation.Furthermore,theuseoflayeredencodingtechnologiesfortheoff-linegenerationofadaptedversionsallowsachievingsignificantadvantages.Layeredencodingallowsgeneratingonlyoneadaptedversionofthecontentfromwhich it ispossible toobtaina suitableversion for anymobiledevice.Basically,thisapproachgeneratesabase layerandoneormoreenhancedlayerstoachievethedesiredresolutionofthemultimediacontent.Layersmaybeaddedordroppeddepending on the requirements of the mobile device. A popular technology forlayeredencodingisScalableVideoCodecs(SVC)[23],wheretheenhancedlay-ersmayadd temporaland/or spatialquality to thebase layer.TheuseofSVCprovides important benefits from the computational and storage points of viewforsystemsadoptingoff-lineadaptationsolutionsforsupportingMobileWeb2.0services.Theoriginalmultimediacontent, indeed,has tobeencodedonlyonce,andtheresultisascalableadaptedversionfromwhichrepresentationswithlowerqualitycanbeobtainedbydiscardingpartsofthedata.Thissolutionavoidstheneedofstoringmultipleversionsofthesamemultimediacontenttosatisfyanypos-siblecombinationofrequirementsofmobiledevicesandwirelessnetworks, thussimplifyingeventheserver-sideapproachtothecontentadaptation.

Tothisaim,weshouldconsiderthatthetechnologicalevolutionofthemobiledevicesmayhavepositiveconsequencesfortheoff-lineapproach,becauseresourceswillnotneedtobetailoredexactlyforeverytypeofclientdeviceasithappeneduntilnow.Forexample,whilethefirstgenerationofdevicesrangedfrommono-chrometofull-colorcapabilities,moderndevicescandisplayatleast16-bitcolorimages; hence previous adaptations from color to B/W videos are now useless.Thankstothetechnologicalimprovements,differentdevicesarenowabletocon-sume the same version of a multimedia resource, thus reducing the number ofadaptedversionsthatmustbegeneratedforeveryoriginalresource.Ontheotherhand, thepresenceofuser-generatedcontent in theMobileWeb2.0 scenario iscausinganexplosionofmultimediacontents in termsofquantityandheteroge-neity[1,8].WeshouldalsoconsiderthattheworkingsetofaccessedmultimediaresourcesinMobileWeb2.0ishighlyvolatile.Indeed,theresourcesarecharacter-izedbyashort lifespan,becausetheytypicallyconcernreal-worldeventsorhottopics forwhichuser interest rapidly subsides.For these reasons, apureoff-linesolutionmaybenotfeasibleorconvenientduetotheexcessivewasteofstorageandcomputationalpowercausedbypre-generatingandmaintainingadaptedversionsforeverymultimediaresource.

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Ahybridsolutionthatcombineon-the-flyandoff-linecontentadaptationmayrepresentabetterchoicetosupportMobileWeb2.0services.Apossiblesolutioncon-sistsinapplyingoff-lineadaptationonlytoalimitedsetofthemostpopularresources,while adapting on-the-fly the remaining resources [6]. The rationale behind thisapproachoriginatesfromthepopularityofmultimediaresourcesinMobileWeb2.0,thatfollowsaZipf-likedistribution[8,33].Thismeansthatpre-generationofadaptedversionsforalimitedfractionofpopularresourcesallowsasystemforMobileWeb2.0servicestosatisfyahighnumberofuserrequests.Fortheremainingrequests,adaptationmaybeappliedon-the-flywithoutovercomingthecapabilitiesofserverinfrastructures.However,identifyingthemostpopularresourcesrepresentsanopenchallengeespeciallyinthecontextofMobileWeb2.0,whoseworkloadischaracter-izedbyhighvolatility,shortresourcelifespan,andsuddenpopularitypeaks.

5.4.5 Location-Related FunctionsThepossibilitytogeographicallylocateamobiledeviceandexploitthisinformationtoenrichtheuserexperienceisoneofthemostinnovativefeaturesofMobileWeb2.0.Twomainfunctionsareneededtosupportthisfeature:computationofdevicelocationandgeo-referencedinformationmanagement.

5.4.5.1 Computation of Device Location

Severalsolutionsmaybeexploitedforpositioningpurposes,thatis,determiningthegeographicallocationofamobiledevice.Positioningisusuallyperformedbyfollowingaclient-sideapproach,wherethecomputationofthelocationiscarriedoutonthedevice,thencommunicatedtotheservice.

The most popular positioning technology is the Global Positioning System(GPS),whosewideadoptionisduetothelargediffusionofmobiledevicesequippedwithGPSreceiversthatprovidereliablethree-dimensionallocation(latitude,lon-gitude,andaltitude).However,relyingontheGPStechnologyforpositioningmaypresenttwomaindrawbacks:thelongtimetakenbythemobiledeviceduringthestart-upphasetolookforavailablesatellites(between45and90sonaverage),andtheconsequentconsiderablecostofcomputationalandbatterypower.

Toovercometheselimitations,theassistedGPS(A-GPS)hasbeenintroducedinthelastfewyears.A-GPSisacarriernetworkdependentsystemthatcanimprovetheinitialperformanceofaGPSsatellite-basedpositioningsystem.Basically,theA-GPSusesanassistanceserverthatcommunicatestothemobiledeviceinforma-tionontheavailablesatellitestoacceleratethesignalacquisition.

Inspecificconditions,suchasinindoorenvironments,analternativetechniquetoprovidepositioning is to exploit cellular orWi-fi triangulation,basedon thedevicedistancefromcelltowersorWi-fiaccesspoints.ItisworthtonotethatGPS-and triangulation-based technologiesmayalsobeemployed together to improvepositioningaccuracy[31].

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Althoughmobiledeviceshavebecomemorepowerful,theydonotalwayshavethecomputationalpowernecessarytocomputetheircurrentlocationthroughGPSortriangulationtechniques.Weshouldalsoconsiderthatthecomputationalcostoftheoperationdependsontheaccuracyrequiredbythespecificservice,andonthefrequency/speedoftheusers’movements,thatmaycausefrequentrecomputa-tionsoftheexactlocation.Inthiscase,thecomputationmaybeexecutedontheserverside.TheserverinfrastructurereceivesfromthemobiledevicesGPS-and/orcell-basedinformationandcalculatesthelocationandtransmitstheresulttothedevices.

5.4.5.2 Geo-Referenced Information Management

Thedevicelocationrepresentsageo-referenceddatathathastobestoredandman-agedontheserverside.Thepresenceofgeo-referenceddatarequirestheuseoftech-nologicalsolutionsthatallowoperationsonspatialdata.Forexample,thesystemshouldbeabletofindallthepointsofinterestthatareclosetoagivenuserlocationortoidentifytheshortestpathamongtwogivenlocations.ThisrequirementmaybeaddressedbyspecializedGeographicInformationSystems(GIS)orbydatabasesystemsthatsupportthestorageandmanagementofspatialdata.

However,thisrequirementdoesnotrepresentanopenissue,duetothewidediffusion of GIS technologies and database systems with spatial support (e.g.,MySQL,PostgreSQL,Oracle,MicrosoftSQLServer).

Another importantcharacteristic formanagementpurposes isthepotentiallydynamicnatureofthedevicelocationdatathatmaychangefrequentlyduetousermovements. Traditional approaches for data replication are not suitable to storeandmaintainpotentiallydynamicuserlocationduetoconsistencyissues.Forthisreason,acommonlyadoptedsolutionistomaintaintheuserlocationattheappli-cationserverlevel justforthedurationofthecurrentusersession.Ontheotherhand,locationdatareferringtoPOIsmaybestoredindatabasesduetotheirmorestablenature.

Alastconsiderationaboutthemanagementofgeo-referencedinformationisthatthecurrentlocationisusuallyconsideredbytheusersasasensitivedata[29].Hence,MobileWeb2.0servicesshouldprovideuserswithappropriatemechanismstocon-trolthedisclosureoftheirlocation.Thisissueistypicallyaddressedontheserverside.Afirstsolutionconsistsinallowingtheusertoeditalistofauthorizedcontactsthatmayaccesshislocation.Theusermusthavethepossibilityofmodifying/updatingtheauthorizationlistthatismaintainedintheuserprofileontheserverinfrastruc-ture,atanymoment.Thisisparticularlyimportantinthecontextofpeoplediscov-eryservices,becausetheusers’movementsarecontinuouslytrackedtocommunicatetheirpresencetonearbycontactsevenwhentheyarenotactivelyinteractingwiththeapplication.Amoresophisticatedapproachtopreservetheprivacyoftheuserconsistsin revealing theuserpositionwithdifferent accuracies,dependingon the specificlocationand/orontherecipientoftheinformation[2].

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5.5 ConclusionsThepopularityofWeb2.0 services, coupledwith thediffusionof increasinglypowerfulWeb-enabledmobiledevices,hasledtotheadventofMobileWeb2.0.Thisemergingscenario includesverycomplexandheterogeneousservices: someservicesaretotallynew,basedonthenotionofuserlocation,whileothersareextensionsofexistingWeb2.0servicestoamobilecontext.Thedeploymentofnewandextendedservicesmaybehinderedbythelimitedcapabilitiesofmobiledevicesintermsofdis-play,computationalpower,storage,andconnectivity.Hence,thechoiceofappropriatetechnologicalsolutionsisakeyelementtoeffectivelysupportMobileWeb2.0services.

WeclassifytheemergingMobileWeb2.0servicesandweidentifysomekeyfunctionsrequiredfortheirsupport,discussingpossibletechnologicalsolutionsforthe implementationof each function.We show that existing technological solu-tionsare sufficient to implementmost functions;hence theproblem is a correctintegrationandcapacitydesign.Ontheotherhand,theimplementationofotherfunctionsrepresentsachallengethatdeservesfurtherresearchefforts,asinthecaseofprovidingcomfortableinterfacesforuserinputandlargefileupload.

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31. S.J.Vaughan-Nichols.Willmobilecomputing’sfuturebelocation,location,location?IEEE Computer Magazine,42(22):14–17,2009.

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Author Queries[AQ1] PleaseprovidecaptionforFigure5.1.[AQ2] Pleasecheckiftheeditstothesentencestarting:“Theupload…POIdis-

coveryservices.”areok.[AQ3] Pleasecheckiftheeditstothesentencestarting:“Although…ispossible.”

areok.[AQ4] PleasecheckiftheinsertedexpansionfortheacronymAPIisok.[AQ5] PleasecheckiftheinsertedexpansionfortheacronymSDKisok.[AQ6] PleasecheckiftheinsertedexpansionfortheacronymMMSisok.[AQ7] PleasecheckiftheinsertedexpansionfortheacronymRSSisok.[AQ8] PleaseprovidecompletedetailsinRefs.22and30,ifappropriate.

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Technological Solutions to Support Mobile Web 2.0 Services · new friends (e.g., Facebook, MySpace, Friendster). TheBlogging services allow a user to create and manage a blog, that