Functionallevel
(1)Physicallayer:Itisthephysicalstoragedescriptionofthemultimediadatabase,thatis,theformdescribeshowthemultimediadataisstoredonthephysicalstoragedeviceofthecomputer.Formultimediadatabases,theactualdataisallowedtobescatteredindifferentdatabases.Forexample,inthemanagementofmultimediapersonnelfiles,aperson'svoiceandphotosmaybestoredinasounddatabaseandimagedatabase,andhisotherpersonnelrecordsmaybestoredinarelationaldatabase.
(2)Conceptlayer:Itrepresentstheabstractstructureoftherealworld,andisthedescriptionoftherealworldthings.Multimediaapplicationdeveloperscanuniformlymanagevariousmultimediadatastoredinthemultimediadatabasethroughthedatabaselanguageprovidedbythislayer.
Theconceptuallayerconsistsofasetofconceptualobjects.Theobjectsinvolvedintheconceptualobjectmaycomefromseveraldatabases.Forexample,peoplearedescribedbypersonnelrecords,photos,etc.,whichmaycomefromgeneralrelationaldatabasesandimagedatabases,respectively.Attheconceptuallevel,theschemamustbedefinedinaccordancewiththeconceptualschemaofseveraldatabases.
(3)Presentationlayer:Itcanbedividedintoviewlayeranduserlayer.Theuserlayeristheexternalmanifestationofthemultimediadatabase,thatis,thetables,graphics,pictures,andplayedsoundsthattheusercansee.Theuserlayercanbedescribedbyaspecialmultimedialayoutspecificationlanguage,andprovideuserswithaninterface.Theperformancemodeofmultimediadatamanagementsystemisanissuethatneedsattentionintheresearchofmultimediadatabasesystem.Sincetherepresentationofvariousunformatteddataisdifferent,andthereisacertaincorrelationbetweenthem,thepresentationlayerinthemultimediadatabasesystemiscomparedwiththetraditionaldata
Architecture
(1)Federalstructure
Themanagementofmultimediadataiscarriedoutseparately,andthedesignofeachmediadatabasedoesnothavetoconsidermatchingandcoordinationwithothermedia.
(2)Centralizedandunifiedstructure‘
Thereisonlyasinglemultimediadatabaseandasinglemultimediadatabasemanagementsystem.Variousmediaaremodeleduniformly,themanagementandmanipulationofvariousmediaarecentralizedinadatabasemanagementsystem,andtheneedsofvarioususersareunifiedintoamultimediauserinterface,andtheresultsofmultimediaqueryandretrievalcanbeuniformlyexpressed.
(3)Client/servicestructure
Varioussinglemediadataarestillrelativelyindependent.Thesystemusesaservertoimplementthemanagementsystemandmanipulationofeachmedia.Thisarchitectureisalsoeasytoextendtoworkinanetworkenvironment.
ResearchApproaches
Therearemanyresearchapproachesformultimediadatabases,andthefollowingfivemethodsarecommonlyused.
(1)Improvetheobject-orienteddatabasetomakeitsuitableformultimediadataprocessingsoastobegraduallyacceptedbyusers.
(2)EstablishmultimediaMISandGISintheexistingrelationaldatabase.
(3)Simpleexpansionoftherelationaldatabase,sothatithasthesimplestmultimediafunctions,suchasOracle,Sybase,etc.,haveexpandedthelongfieldtype,upto2GBofspace,storingvariousmultimediadata.However,thisexpansiononlystoresmultimediadataintheformofcharacters,anddoesnotsolvetheproblemofretrievalandprocessingofmultimediainformation.
(4)Thetheoryandtechnologyofrelationaldatabaseandthetheoryandtechnologyofobject-orienteddatabasearecombined.Ontheonehand,itcanberealizedquicklyandeconomicallybyusingthematuretechnologyofrelationaldatabase;ontheotherhand,object-orientedPartofthedatabasetechnologyisextendedtotherelationaldatabase,sothatithassomebasicfunctionsoftheobject-orienteddatabase.
(5)Introducehypermediamechanism.
Features
Multimediadataissignificantlydifferentfromtraditionaldatabasedata.Multimediadatabaseshavethefollowingcharacteristics.
①Theamountofdataishugeandthedifferenceintheamountofmediaisveryobvious,whichmakestheorganizationmethodandstoragemethodofthedatainthelibrarycomplicated.
②Thevarietyofmediamakesdataprocessingverycomplicated.Fourtypesofmultimediadatawereintroducedintheprevioussection,butinactualimplementation,theyoftenevolveintodozensofmediaformatsbasedonsystemdefinitionsandstandardconversions.
③Multimediahasnotonlychangedtheinterfaceofthedatabase,makingitsound,picture,andtextual,butalsochangedtheformofdatabasemanipulation,themostimportantofwhichisthequerymechanismandquerymethod.Thecomplex,scattered,sequentialnatureofthemediaanditsvisualcharacteristicsmakethequerynolongerjustquerybycharacters,andtheresultofthequeryisnotonlyatable,butasetof"representations"ofmultimedia.Themultimediainterfacewillputforwardmorecomplexandfriendlydesignrequirementsforthequery.
Function
(1)Themultimediadatabasesystemmustbeabletoexpressandprocessvariousmediadata.
(2)Themultimediadatabasesystemmustbeabletoreflectandmanagethecharacteristicsofvariousmediadata,orthetimeandspacerelationshipbetweenvariousmediadata.
(3)Thequeryofmultimediadatashouldbebasedoncontent,butthecontentshouldbedescribedinadvance.
(4)Themultimediadatabasesystemshouldbeopen,provideapplicationprograminterfacesandprovideinterfacesindependentofperipheralsandformats.
(5)Thedataoperationfunctionofthemultimediadatabasesystemshouldnotonlyprovidequeryandsearchfunctionsforunformatteddata,butalsoprovidedifferentoperationmethodsfordifferentmedia,suchaseditingandprocessingofgraphicsandimages.Editingofsounddata,etc.
(6)Thenetworkfunctionofthemultimediadatabasesystem.Sincemultimediaapplicationsaregenerallynetwork-centric,problemssuchasthedefinition,storage,andoperationofdatainmultimediadatabasesdistributedonthenetworkshouldberesolved,andtheconsistencyandsecurityofthedatashouldbemanaged.
(7Themultimediadatabaseshouldprovidetheabilitytodealwithlong-termaffairsandversioncontrol.