A modelof requestsaboutactionsfor active componentsin thesemanticweb

In thispaper , weaddresstheproblemof answeringformalrequestsabout actionsfor activecomponentsthatcanbefoundin onlineservicesontheInternet.The componentsaredescribedusinga specificlanguageandhave accessat runtime to a formal specificationof their actionsandcurrentstates.We presenta formal model for requestsaboutactions,basedon the combinationof speechactsandprocedural types, that allows us to representhe differentkinds of questionsthat a humanuser canaskabouttheactions,behaviour andactivity of anactivecomponent.We propose answeringalgorithmsandwe illustratethemonsomeexamples. 1 Presentationof the problem 1.1 Activecomponentsin thesemanticweb Thesemanticwebis anextensionof thecurrentwebin which informationis describedin a well-definedmanner[2], in orderto allow softwarecomponentsto performautomaticprocessingbasedon thepagecontentsandthesemanticsof thesecontents(extractionandpresentationof theinformation,automaticservicesactivation,etc.). Thecurrenttrendspropose to make useof knowledge representationtechniquesto enhancewebpagesinformationwith semantics. Theemergenceof standardsfor structural knowledgerepresentation, likeDAMLOIL andRDF, allowedresearchers to offer betterservicesin informationretrieval: semantic requests, semanticdocumentindexing, etc. In this context, onlineserviceson theInternetled to thenotionof activecomponents , i.e. softwarecomponentscharacterisedby actionsandcapableof providing servicesto theusers [4, 9]. Active componentscannotbe reducedto simplesoftwaresystemsusedto processor produceinformationin the web. They arepart of this informationwhich is no longeronly structuralbut alsofunctional.As a consequence, in the samemannerstructuralknowledge canbe queried,active componentsin the semanticweb shouldbe able to explain to users “whatthey aredoing”. Within the InterViews[19] project,we try to developandto implementsuchactivecomponents,capableof representingtheir own actions,reasoningaboutthemandinteractingin naturallanguagewith users,in order to answera large rangeof questionsabouttheir behaviour andexecution. Thework donewithin thefield of “reasoningaboutactions”[12, 16] constitutesthefoundationsof this approach,sinceit providesthetoolsrequiredwhenproducinganexplanation 2 A modelof requestsaboutactionsfor activecomponentsin thesemanticweb ρ= What are you doing? Question about actions in natural language Formal request Active component description Building a formal answer Figure1: Processingquestionsaboutactionswithin theInterViewsproject. [21] for theuser. We takehereaninterestin definingamodelfor questionsaboutthecomponentsdynamicalstructureandexecution.Our aim is to proposea formal requestmodelsuch that: aNaturalLanguageProcessingModule(NLPM) couldtranslateawideclassof questions aboutactionsinto a request 1, a ReasoningaboutActionsModule(RAM) caninterpretit to build ananswerfollowing thesameschemethat’ll beusedin turn to produceanaturallanguageanswer . To this end,we shall usea specificcomponentrepresentationmodel (seesection2.1) that allowsusto know aboutits dynamicandstaticstructureat runtime. Figure1 illustratesthis process. 1.2 Consider ationsabouttheformal requestsmodel In orderto build our requestmodel,we first classifiedthequestionsthata humancouldask aboutan active component’ s actionsandbehaviour, usinga “Wizard of Oz” approach.We thenseparatedthenaturallanguageprocessingproblemsfrom theproceduralones. In this paper , we usea complementaryapproach:startingfrom a descriptionformalism usedto describea component’ s actions,we proposea requestmodelthat takesinto account the behaviour studyalongwith the possibility to integratethe differentkinds of questions considered.We classify the possiblerequestsaccordingto the answeringmechanismsthey involve. We first presentthe representationformalismusedfor the componentsdescribedhere. We thenproposea modelfor requestsaboutactionsandwe give thegeneralframework for building a formal answer . Eventually, we show that this modelfits well with modellingthe classof questionsaboutactionswebroughtout. 1We will call questionsthe naturallanguageinteractionsand requeststhe formal ones,shouldthey come from a humanquestionor from anotheractivecomponentover thenetwork (e.g. in theweb). A modelof requestsaboutactionsfor activecomponentsin thesemanticweb 3 2 Presentationof VDL 2.1 General principle In the InterViews project,componentsaredescribedin a specificlanguagecalledVDL for View DesignLanguage. Thesoftwarecomponent’ sdescriptionin VDL is atreewhosenodes arecharactersstringscalledconcepts. We call this concepttreea view like in Forbus QPT [8]. A view is theformal representationin VDL of theactivecomponent’ sdatastructureand actions. A component’ s runtime is basedon rewriting the view at eachexecutionstep, like in Gurevich’s Evolving Algebras[10]: we defineda function that looks in the view for specificconceptsthat are interpretedto build the ! #"%$ view. The componentsthusare modeless : they canrun without any userinteraction. Our first aim wasto proposean extensionto XML that could allow the programmerto attachactionsto structuralinformation,in orderto describeandto runanactivecomponent as awebpage.However, it appearedthatDTDscouldonly beusedto describevalidatingstatic parsers, i.e. function that link tagswith staticsemantics.Our aim wasto describenot only staticparsers, but alsoonedynamictransducer( & ' ( ) thatgivestagsprocedural semanticsin orderto build anew XML page.Therefore,we decidedto baseour work on amoreclassical model,thatcouldhelpusto focuson theactionsrepresentationproblem:therewriting trees. This led usto proposea specificlanguage, whosestructuralpartis verysimple(conceptsare reducedto merecharacterstrings),but thatcouldeasilybe linkedto markuplanguageslike XML. We totally definedthis language’ s operationalsemanticsin [17] andwe implemented it in Java1.1. 7.2