Query rewriting for open XML data integration systems

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Queryrewritingfor

openXMLdataintegrationsystems

Abstract

ThispaperpresentsOpenXView,amodelforopenXMLdataintegrationsystems,characterizedbytheautonomyofusersthatpublishXMLdataonacommontopic.Autonomyimpliesfrequentandunpredictablechangestodataandahighdegreeofstructureheterogeneity.TheOpenXViewmodelprovidesanoriginalintegrationschema,basedonahybridontology-XMLschemastructure.Weproposesolutionsfortwoimportantproblemsinsuchsystems:easyaccesstodatathroughasimplequerylanguageoverthecommonschemaandsimpleintegrationviewmanagementwhendatachanges.ThispaperfocusesonthequeryrewritingprobleminOpenXView,forwhichexistingalgorithmsarenotsuitable,andproposesaquerytranslationalgorithm.

Keywords:XML,heterogeneousdataintegration,ontology,queryrewriting,local-as-view

1Introduction

ManycompaniesarenowconsideringstoringtheirdatainXMLrepositories.Hence,theintegrationandtransforma-

tionofsuchdatahasbecomeincreasinglyimportantforapplicationsthatneedtosupporttheiruserswithquerying

environments.

WeaddressheretheproblemofXMLdataintegrationinaparticularcontext.First,weareinterestedinopen

integrationsystems,whereusersmayfreelypublishdatainthesystem,inordertoshareinformationoncommon

interesttopics.Atypicalexampleispeer-to-peer[8]communities,initiallysharingmultimediaﬁles,butcurrently

focusingmoreandmoreonstructuredcontent,suchasXMLdata.Thekeycharacteristicofopenintegrationsystems

isuserautonomyinpublishingdata.Frequentandunpredictablechangestodataandschemas,asuserspublishnew

informationisaﬁrstconsequenceofuserautonomy.Theotherimportanteffectofautonomyisdataheterogeneity,for

documentscomingfromdifferentusers,thathaveindependentlydesignedthestructureoftheirdocuments.

ThedataintegrationmodelwehavechosenforsolvingthisXMLdataintegrationproblemisnovel.Usually,the

common(target)schemaforXMLdataintegrationiseitheratree-likeXMLschema,oranontology.Intheformer

case,theadvantageisalowmodelmismatch,i.e.agoodadequacyofthecommonschemamodelwithsourcedata

andwithqueryresults(XMLdata).Thedrawbacksarealimitedsemanticexpressivenessandsomerigidityindata

typingatqueryprocessing:thesystemoftenmatchesonlyresultsthatpreserveinsourcesthesamerelationsbetween

thequeriedelementsinthecommonschema.Ontologieseliminatethesedrawbacks,butthemodelmismatchbetween

XMLschemasandontologiescomplexiﬁestheexpressionofmappingsbetweensourcesandthecommonmodel.

WeproposeamodelthatcombinestheadvantagesofontologiesandXMLschemas,bydeﬁningahybridintegra-

tionschema:asimpleontology,whereconceptshavepropertiesorganizedinhierarchies(suchasinXMLschemas),

butmaybeconnectedthroughtwo-way“relatedTo”relationships,moreﬂexibleatqueryprocessing.

Onthesourceside,userspublishXMLschemasanddocuments.Weintroducedin[1]thenotionofPhysical

DataView(PDV),betteradaptedtodataintegrationthantheXMLschemaspublishedbythesources.APDVisa

viewonarealschema;ithasatree-likestructure,gatheringaccesspathstousefulnodesintherealschema,and

mappingsbetweenthistreeandtheontologygraph.Mappingsareexpressedthroughsimpletwo-way,node-to-node

correspondencesbetweenPDVandontologynodes.ThedifferencebetweenapublishedXMLschemaandaPDVis

subtle.Ontheonehand,evenifnotmandatory,aPDVmaydiscarduselessnodesintheXMLschema,byremoving

subtreesorbyreplacingapathbetweentwonodesbyasingle“//”edge.Removingnodeshelpsimprovingschema

management,storageandqueryprocessing.ThePDVtreeisactuallyadataguide,asummaryofaccesspathsto

nodesusefulforqueries.Ontheotherhand,PDVsproducedfromsourceXMLschemas,unliketheseschemas,

provideauniquewaytotranslateuservisibleontologynodes,byassociatingwitheachontologynodeatmostone

nodeinasinglePDV.ThisimpliesthatapublishedXMLschemamayproduceseveralPDVs.Eachtimeaschema

ispublished,thesystemmustassisttheusertogeneratePDVs,throughsemi-automaticprocedures.Thisadditional

effortatpublishingtimeislargelyjustiﬁedbytheeffortsavedatqueryrewritingtime,whenheavycombinatorial

computationandpossiblywrongrewritingsareavoided.

Figure1illustratesthedifferencebetweenPDVsandXMLschemasthroughasimpleexample.Theontology

containsasingleconcept(Artist)withthreeproperties(name,country,birthdate).ThepublishedXMLschemaisa

treecontaininginformationabouttwokindsofartists:ﬁlmdirectorsandactors.TwoPDVsareobtainedfromthis

schema,soastodissociatedirectorsfromactorsbothmappedtoconceptArtistintheontology,eachoneproviding

Artist

namecountrybirthdatenamebirthdatecountrydirectoractor

namecountrytitlemoviecast

role

namebirthdatecountrydirectoractor

namecountryPhysical data views (PDV)

//XML document schemaOntology

//PDV1PDV2

Figure1:XMLdocumentschemavsPhysicalDataView

auniquetranslationfortheartist(possiblyincomplete,e.g.actorslackbirthdate).Uselessnodesareremovedfrom

eachPDV;thisproducesa“//”edgeabovetheroot:e.g,nodesmovie,castandroleremovedwhencreatingPDV2.

Reusing Mechanical Engineering Design

ZoE LACROIX

Department of Mechanical and Aerospace Engineering

Arizona State University

PO BOX 876106

Tempe A2 85287.6106, USA

Abstract-Design in mechanical engineering

is often re- design and involves retrieving

similar designs from various integrated design

repositories or paper drawings. To sup- port

designers a SyStem must provide to

previous valid designs that satisfy satisfy

requirements, functions, or Characteristics,

and allow the integration and transformation

of the retrieved designs into a new design

that meets the new design specifications.

Many approaches have been developed in

the past to support designers in accessing

dcsigns for their new design needs. Most of

ex- isting approaches typicalb store design

documents as files and provide an

SSH框架整合常见异常

spring+hibernate出错小结:

(1)ng.NoClassDefFoundError: org/hibernate/context/CurrentSessionContext

原因：出现这错误时，请更改hibernate的包，更新至最新或3.1以上

(2)ng.NoClassDefFoundError: javax/transaction/TransactionManager

原因：缺少jta.jar 或者是找不到hbm.xml文件导致sessionfactory出错，检查hbm文件路径是否正确，文件是否存在

(3) 错误：

Exception in thread "main" org.hibernate.exception.SQLGrammarException: Could not

execute JDBC batch update

或者org.springframework.jdbc.BadSqlGrammarException: Hibernate operation: could not

insert: [com.yourcompany.model.Login]; bad SQL grammar [insert into mysql__login

(name， password) values (?， ?)]; nested exception is java.sql.SQLException: Table

'mysql.mysql__login' doesn't exist java.sql.SQLException: Table 'mysql.mysql__login'

doesn't exist

原因与解决：因为Hibernate Tools（或者Eclipse本身的Database Explorer）生成*.hbn.xml工具中包含有catalog="***"（*表示数据库名称）这样的属性，将该属性删除就可以了

原文

Visualization of PLC Programs using XML

M.Bani Younis andG.Frey

Juniorprofessorship Agentenbased Automation

University of Kaiserslautem

P. 0. Box 3049, D-67653 Kaiserslautem, Germany

Abstract- Due to the growing complexity of PLC programs there is anincreasing interest in the application of formal methods in this area. Formal

methods allow rigid proving of system properties in verification and

validation. One way to apply formal methods is to utilize a formal design

approach in PLC programming. However, for existing software that has to

be optimized, changed, or ported to new systems .There is the need foran approach that can start from a given PLC program. Therefore,

formalization of PLC programs is a topic of current research. The paper

outlines a re-engineering approach based on the formalization of PLC

programs. The transformation into a vendor independent format and the

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Query rewriting for open XML data integration systems

合集下载

Reusing Mechanical Engineering Design

SSH框架整合常见异常

原文

xml标准文件说明

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