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1、Acoi:ASystemforIndexingMultimediaObjectsMenzoWindhouwerAlbrechtSchmidtMartinKerstenwindhouw@cwi.nlalbrecht@cwi.nlmk@cwi.nlCWIKruislaan413NL-1098SJAmsterdamTheNetherlandsAbstractInthispaper,wepresentasystemthatcombinesindependentfeaturedetectorprogramswithmultimediadatabasete
2、chnologytoprovideasemanticrichindextomultimediadataitemsontheWorldWideWeb.First,weintroduceagrammaticalframework,calledfeaturegrammars,whichformstheindexingschema.Featuregrammarsareanextensionofcontext-freegrammarswithactivesymbols(e.g.multimediafeaturedetectors)thatmayinvok
3、efeaturedetectorprograms.TheAcoisystemreadsinthegrammar,compilesitandexecutesitagainstadatasource,e.g.amultimediaobject.Thederivedparsetreeisusedasanindextothisdatasource.Itsstructurecloselyresemblesthatofsemi-structured(XML)documents.Then,wepresentthearchitectureofourimplem
4、entationontopofMonet,ourextensiblemainmemorydatabasesystem.Inthisimplementation,featuregrammarsareusedasadescriptionoftheexecutionsequenceoftheindexingprogram.WeshowhowtheresultingparsetreecanbestoredefficientlyinMonet.ASQL-likequerylanguageenablesuserstousethefeaturegrammara
5、saschemaforqueryformulationtoretrievebothindexvaluesandtheoriginaldatasources.Throughoutthepaper,weillustratetheconceptswitharunningexampleofagrammarusedforindexingHTMLpagesandmultimediaobjectsontheWorldWideWeb.Keywords:multimediadatabases,featuregrammars,multimediaindexing1
6、IntroductionWiththeexplosivegrowthoftheamountoflinkedmultimediaobjects,i.e.thebuildingblocksoftheWorldWideWeb,the`lostincyberspace'problemaggravates.Therearenumerousapproachestoalleviatetheproblemstudiedinthecontextofdigitallibraries[AR97,WAS98].Topicsincludenavigationandque
7、ryformulationfacilities,anddatabasesupportforbothofthem.Inthispaperwefocusonthedatabasesupportformultimediaqueryfacilities.Searchingforobjectsonthewebismainlysupportedbyconstructingameta-index.Wellknownmeta-indexesarethesearchengines,e.g.AltaVista,widelyusedtofindspecificHTMLp
8、ages.Theseindexesarebasedonkeywordsextractedfromthepagedescription.Theequiv
