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XML and Windows CE 3.0

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XMLandWindowsCE3.0<?xml:namespaceprefix=ons="urn:schemas-microsoft-com:office:office"/>

MichaelReeves
MicrosoftCorporation

November2000

Summary:WindowsCE3.0operatingsystemextendstherangeofoptionsavailabletodevelopersbyprovidingasubsetofExtensibleMarkupLanguage(XML)functionality.ThisdocumentdescribesthefeaturesofXMLthathavebeenincorporatedintoWindowsCEandthedifferencesbetweenusingXMLonaWindowsCE–basedplatformandonaWindows-baseddesktopcomputer.(9printedpages)

Content

Introduction
ExtensibleMarkupLanguage

WebServicesandXML
XMLforWindowsCE

ValidatingData

DocumentManagement

FormattingComplexDataforPresentation

XMLHTTP

InstantiationofCOMObjectsThroughXSL

Introduction

TheMicrosoft®Windows®CE3.0operatingsystemextendstherangeofoptionsavailabletodevelopersbyprovidingasubsetofExtensibleMarkupLanguage(XML)functionality.ThisdocumentdescribesthefeaturesofXMLthathavebeenincorporatedintoWindowsCEandthedifferencesbetweenusingXMLonaWindowsCE–basedplatformandonaWindows-baseddesktopcomputer.ForgeneralinformationaboutXML,seethedocumentationavailableintheMSDNOnlineLibrary.(Notethatthroughoutthisarticle,MSXMLreferstotheXMLparseravailablefromMicrosoft,andXMLreferstothemarkuplanguage.)

ExtensibleMarkupLanguage

XMLisameta-markuplanguagethatprovidesaformatfordescribingstructureddataandallowsdeveloperstoeasilydescribeanddeliverrich,structureddatafromanyapplicationinastandard,consistentway.XMLfacilitatesmoreprecisedeclarationsofcontentandprovidesmoremeaningfulsearchresultsacrossmultipleplatforms.Inaddition,XMLisenablinganewgenerationofWeb-basedapplicationsforviewingandmanipulatingdata.

ThepowerandbeautyofXMLcomesfromitsmaintainingtheseparationoftheuserinterfacefromthestructureddata.WhileHypertextMarkupLanguage(HTML)tagscandisplayawordinboldfaceoritalics,XMLprovidesaframeworkfortaggingstructureddata.AnXMLtagcanindicatethatthedataassociatedwiththetagisaretailprice,asalestax,abooktitle,anamountofprecipitation,oranyotherdesireddata.AsXMLtagsareadoptedbyorganizationsfortheirintranets,andbyothersacrosstheInternet,theabilitytosearchforandmanipulatedata,regardlessoftheapplicationswithinwhichthedataresides,willincrease.OnceanapplicationlocatesXMLdata,theapplicationcandeliverthedataoverthenetworkandpresentthedatainaWebbrowser(suchasMicrosoft®InternetExplorer)inanynumberofways,ortheap
4000
plicationcanhandoffthedatatootherapplicationsforfurtherprocessingandviewing.

XML,whichprovidesadatastandardthatcanencodethecontent,semantics,andschemataforawidevarietyofcasesrangingfromsimpletocomplex,canbeusedtomarkupthefollowing:

Anordinarydocument

Astructuredrecord,suchasanappointmentrecordorpurchaseorder

Anobjectwithdataandmethods,suchasthepersistentformofaJavaobjectorActiveX®control

Adatarecord,suchastheresultsetofaquery

MetacontentaboutaWebsite,suchasChannelDefinitionFormat(CDF)

Agraphicalpresentation,suchasanapplication'suserinterface

Standardschemaentitiesandtypes

AlllinksbetweeninformationandpeopleontheWeb

Oncethedataisontheclientdesktop,itcanbemanipulated,edited,andpresentedinmultipleviewswithoutreturntripstotheserver.Serverscannowbecomemorescalable,duetolowercomputationalandbandwidthloads.Also,becausedataisexchangedintheXMLformat,itcanbeeasilymergedfromdifferentsources.

WebServicesandXML

Unlikecurrentcomponenttechnologies,Webservicesdonotuseobject-model-specificprotocolssuchasDistributedComponentObjectModel(DCOM),RemoteMethodInvocation(RMI),orInternetInter-ORBProtocol(IIOP)thatrequirespecific,homogeneousinfrastructuresonboththeclientandservicemachines.Whileimplementationstightlycoupledtospecificcomponenttechnologiesareperfectlyacceptableinacontrolledenvironment,theybecomeimpracticalontheWeb.Asthesetofparticipantsinanintegratedbusinessprocesschanges,andastechnologychangesovertime,itbecomesverydifficulttoguaranteeasingle,unifiedinfrastructureamongallparticipants.Webservicestakeadifferentapproach:TheycommunicateusingubiquitousWebprotocolsanddataformatssuchasHypertextTransferProtocol(HTTP)andXML.AnysystemsupportingtheseWebstandardswillbeabletosupportWebservices.

Furthermore,aWebservicecontractdescribestheservicesprovidedintermsofthemessagestheWebserviceacceptsandgeneratesratherthanhowtheserviceisimplemented.Byfocusingsolelyonmessages,theWebservicesmodeliscompletelyindependentofthelanguage,platform,andobjectmodelused.AWebservicecanbeimplementedusingthefullfeaturesetofanyprogramminglanguage,objectmodel,andplatform.

XMListheobviouschoicefordefiningastandardyetextensiblelanguagetorepresentcommandsandtypeddata.Whilerulesforrepresentingcommandsandtypeddatausingothertechniques(suchasencodingasaquerystring)couldbedefined,XMLisspecificallydesignedasastandardmetalanguagefordescribingdata.

XMLisalsotheenablingtechnologyforWebservicecontracts.TheServiceContractLanguage(SCL)isanXMLgrammarfordocumentingWebservicecontracts.BecauseSCLisXML-based,contractsareeasyforbothdevelopersanddevelopertoolstocreateandinterpret.

FormoreinformationaboutMicrosoftWebServices,seeTheProgrammableWeb:WebServicesProvidesBuildingBlocksfortheMicrosoft.NETFramework.

XMLforWindowsCE

MicrosoftWindowsCE3.0supportsasubsetofMSXML2.0functionality.Specifically,WindowsCEdoesnotsupportthefollowingfeatures:

Simpledatatypesonattributes

Additionofan"id"datatypeforelements

Assignmentofdatatypesthroughelementnames

Dataislands

Databinding

MimeTypeviewer

BackwardcompatibilitywiththeMicrosoftXMLDocumentObjectModel(DOM)supportedbyMicrosoftInternetExplorer4.0

Also,WindowsCEprovidesonlylimitedXMLsecurity.

SomeoftheMSXML2.0featuresthataresupportedinWindowsCEare:

XMLvalidationthroughschema,namespace,anddatatypesupport.

TheabilitytobuildandmanagecomplexdocumentsanddatathroughDocumentObjectModel(DOM)support.

WebbrowserformattingthroughExtensibleStylesheetLanguage(XSL)support.

AutomateddocumentrequestsandparsingfunctionsthroughtheuseofXMLHTTPfeatures.

WindowsCEalsosupportstheabilitytoinstantiateComponentObjectModel(COM)objectswithinblocksofanXSLscript,whichisafeatureofMSXML2.5.

ValidatingData

MSXMLforWindowsCEsupportsatechnicalpreviewreleaseofXMLschemata.TheXMLschemasupportisasubsetoftheWorldwideWebConsortium(W3C)XMLdatasubmissionandisfunctionallyveryclosetotheW3CDocumentContentDescription(DCD)submission.

ConsiderthefollowingXMLfile:
<CONTACTS>

   <CONTACT>

       <NAME>StephanieSmith</NAME>

       <BIRTHDATE>1971-07-01</BIRTHDATE>

       <EMAIL>ssmith@abcdef.com</EMAIL>

       <PHONE>(425)111-1111</PHONE>

   </CONTACT>

   <CONTACT>

       <NAME>BillWilliams</NAME>

       <BIRTHDATE>1968-09-17</BIRTHDATE>

       <EMAIL>billw@abcdef.com</EMAIL>

       <PHONE>(425)111-1111</PHONE>

   </CONTACT>

   <CONTACT>

       <NAME>ChristopherJones</NAME>

       <BIRTHDATE>1999-09-08</BIRTHDATE>

       <EMAIL>cjones@abcdef.com</EMAIL>

       <PHONE>(425)111-1111</PHONE>

   </CONTACT>

</CONTACTS>

WiththenewXMLschemasupportinMSXMLforWindowsCE,theabovedatacanbevalidatedagainstaschemabydeclaringthefollowingnamespaceontherootelement:
<CONTACTSxmlns="x-schema:contactSchema.xml">
ThissetstheschemacontactSchema.xmlasthedefaultnamespaceforthedocument.Othernamespacescanbedeclaredthroughoutthedocumentifdesired,but,wherenonamespaceisspecified,thedefaultwillapply.

ThecompleteschemafortheaboveXMLdocumentisasfollows:
<Schemaxmlns="urn:schemas-microsoft-com:xml-data"

   xmlns:dt="urn:schemas-microsoft-com:datatypes">

<ElementTypename="NAME"content="textOnly"/>

<ElementTypename="BIRTHDATE"

            content="textOnly"

            dt:type="date"/>

<ElementTypename="EMAIL"content="textOnly"/>

<ElementTypename="PHONE"content="textOnly"/>

<ElementTypename="CONTACT"content="eltOnly">

  <elementtype="NAME"/>

  <elementtype="BIRTHDATE"/>

  <elementtype="EMAIL"/>

  <elementtype="PHONE"/>

</ElementType>

<ElementTypename="CONTACTS"

             content="eltOnly"

             order="many">

  <elementtype="CONTACT"/>

</ElementType>

</Schema>

Theattribute:
xmlns='urn:schemas-microsoft-com:xml-data'
setsthedefaultnamespacefortheXMLdocumentastheschemanamespace.ThismeansthattheschemamustconformtothesyntaxforXMLschemata.Similarly,theattribute:
xmlns:dt='urn:schemas-microsoft-com:datatypes'

declaresthedatatypenamespace.Thismeansthatdatatypescannowbedeclaredthroughouttheschema.(NotethatthedtprefixonthetypeattributeisusedtotypetheBIRTHDATEvalue.)

DocumentManagement

TheDOMisaplatform-neutralandlanguage-neutralinterfacethatpermitsscriptstoaccessandupdatethecontent,structure,andstyleofadocument.TheDOMincludesamodelforhowastandardsetofobjectsrepresentingHTMLandXMLdocumentsarecombinedandaninterfaceforaccessingandmanipulatingthem.TheMicrosoftXMLParseronWindowsCEhasfullDOMsupportincompliancewiththeW3CDOMrecommendation.Inaddition,italsohastheMicrosoftextensionsthatallowaccesstotypeddataandnamespaceinformation,creationofnodesbynodetype,andsoon.ThefollowingisascriptthatloadsanXMLdocumentcontainingthecontactinformationandusesXSLpatternmatchingtodisplaythephonenumberofthecontactwiththenameof"BillWilliams":
functionshowPhone()

   varroot=Contacts.documentElement;

   varselectedElems= root.selectNodes("CONTACT[NAME='BillWilliams']");

   varbillElem=selectedElems.item(0);

   varphone=billElem.childNodes.item(3).nodeTypedValue;

   alert("BillWilliamsphonenumberis"+phone);

TheselectNodesmethodusesXSLpattern-matchingtoretrieveanodelist.Inthiscase,thescriptlooksforallCONTACTelementsthathaveaNAMEelementwiththevalueof"BillWilliams."Becausethereisonlyoneelementthatmatchesthispattern,selectNodesreturnsanodelistoflengthone.

FormattingCom
ae27
plexDataforPresentation

MSXMLonWindowsCEalsoprovidessupportforXSL,whichallowsformorecomplexdisplayofXMLdata.Forinstance,thepreviouscontactinformationcanbedisplayedinasimpletableformat.ThefirsttaskwouldbetocreateanXSLstylesheet:
<xsl:stylesheetxmlns:xsl="uri:xsl">

 <xsl:templatematch="/">

   <H3>Contacts</H3>

   <TABLEBORDER="1"CELLPADDING="1"CELLSPACING="0">

     <TR>

       <TDBGCOLOR="#C0C0C0"><B>Name</B></TD>

       <TDBGCOLOR="#C0C0C0"><B>Phone</B></TD>

       <TDBGCOLOR="#C0C0C0"><B>Email</B></TD>

     </TR>

     <xsl:for-eachselect="CONTACTS/CONTACT"order-by="EMAIL">

       <TR>

         <TD><I><xsl:value-ofselect="NAME"/></I></TD>

         <TD><xsl:value-ofselect="PHONE"/></TD>

         <TD><xsl:value-ofselect="EMAIL"/></TD>

       </TR>

     </xsl:for-each>

   </TABLE>

 </xsl:template>

</xsl:stylesheet>

ThisparticularstylesheetcreatesatableandusesthevaluesofselectedXMLelementstofillthetablewithinformation.Thestylesheetalsosortstheinformationbye-mailname(usingtheorder-byattributeonthexsl:for-eachelement).NotethattheorderinwhichthecontactinformationisdisplayeddiffersfromtheoriginalXMLdocument.

ThisstylesheetcanbeappliedtotheXMLdocumentthroughtheXMLObjectModel,whichisasetofapplicationprogramminginterfaces(APIs)thatallowinteractionwiththeelementsoftheXMLstructuredtree.ThetransformNodemethodonIXMLDOMNodepassesinanXSLtreeandusesthattreetotransformanXMLnodeintoanoutputstring.Inthefollowingcase,thatstringwillbeanHTMLstringthatgetsinsertedintothecurrentdocument:
functionshowContacts()

   document.write(Contacts.transformNode(ContactsSS.documentElement);

Theabovescriptdisplaysthefollowinginthebrowser:

<?xml:namespaceprefix=vns="urn:schemas-microsoft-com:vml"/>

XMLHTTP

UsingtheXMLHTTPobject,theXMLtreeitselfcanbepostedasanobject.Inthefollowingscript,anXMLHTTPobjectiscreatedandpostsanXMLtreenamed"template"totheserverlocation:
varhttpOb=newActiveXObject("Microsoft.XMLHTTP");

httpOb.Open("POST","http://myServer/postContact.asp",false);

varcontact=template.XMLDocument.documentElement;

contact.childNodes.item(0).text=contactName.value;

contact.childNodes.item(1).text=contactPhone.value;

contact.childNodes.item(2).text=contactEmail.value;

httpOb.send(template.XMLDocument);

TheXMLHTTPobjectanditspropertiesareoutlinedintheIXMLHttpRequestInterfacedocumentationintheMSDNOnlineLibrary.

InstantiationofCOMObjectsThroughXSL

WindowsCEsupportsinstantiationofCOMobjects,suchasActiveXcontrols,throughtheXSLscriptinterface.ThefollowingscriptdemonstratesinstantiationofafictitiousCOMobject,“MyCorp”:
<xsl:script>functionTestCOMObject()

    varObj1=newActiveXObject("MyCorp.MyComponent");

    vary=Obj1.Process();//CreateanewCOMobjectanduseittohandle

 //additionalprocessing.

   returny;

</xsl:script>

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标签： xml windows microsoft instantiation xsl object

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