Directory listing of http: uap.unnes.ac.id ebook biblebook Visual Basic 6 com & Library Books

(1)

The Document

Object M odel

M

ic ro so ft has develo ped a to o l fo r c reating and parsing XML do c uments c alled MSXML. MSXML implements the XML Do c ument Objec t Mo del ( DOM) as defined by the Wo rldwide Web Co nso rtium ( usually c alled W3C) . W3C is an internatio nal standards bo dy that is respo nsible fo r the stan-dards ( suc h as HTML, XML, XSP, and so o n) that are used to ac c ess the Web.

The DOM sto res an XML do c ument as a series o f o b jec ts that c an b e easily ac c essed b y an applic atio n pro gram. MSXML implements DOM as a series o f COM o b jec ts fo r use o n Windo ws-b ased c o mputers. This means that these o b jec ts are independent o f any pro gramming language and datab ase server and c an b e used with Visual Basic , Visual C++, ASP sc ript files, SQL Server, and Orac le 8i witho ut pro b lems.

In this c hapter, I’ll disc uss ho w to use the Do c ument Objec t Mo del to c reate and parse XML do c uments.

Basically beta: The version of the Docum ent Object Model discussed in this book is based on the March 2000 beta release of M SXM L. At the tim e I w rote this chapter, the W3C hadn’t finalized the specifications for DOM, and as a consequence, Microsoft’s im plem entation of it in M SXM L is still subject to change.

The Document Object M odel

(2)

do c ument hierarc hy. In additio n, a number o f o ther o bjec ts are sto red there that c o ntain spec ific piec es o f info rmatio n o r utility func tio ns.

Document hierarchy

The basic DOM hierarc hy is sho wn in Figure 21-1. The ro o t no de o f the hierarc hy is the DOMDocumento bjec t, whic h enc o mpasses the entire XML do c ument. As yo u desc end thro ugh the tree struc ture, o ther no des represent a partic ular piec e o f info rmatio n o r gro up o f info rmatio n in the XML do c ument.

Figure 21-1: View ing the Docum ent Object Model object hierarchy

The basic o bjec t is the XMLDOMNodeo bjec t, fro m whic h all o f the o ther no des are derived. In to tal, there are a do zen different types o f no des. Aside fro m the

DOMDocumento bjec t, all o f the o ther o bjec ts begin with XMLDOM. DOM Document

XM LDOM Element XM LDOM Comment XM LDOM DocumentType XM LDOM PrecessingInstruction

XM LDOM PrecessingInstruction XM LDOM Comment

XM LDOM CDATASection XM LDOM Text

XM LDOM EntityReference

XM LDOM EntityReference XM LDOM Attribute

XM LDOM Element

XM LDOM Text

(3)

457

Chapter 21

✦

The Document Object M odel

✦DOMDocument– This is the highest-level o bjec t in the hierarc hy. It enc o m-passes the entire XML do c ument. It also inc ludes additio nal metho ds and pro perties that c an be used to o btain an XML do c ument o r to c reate o ther no des.

✦XMLDOMAttribute– This o bjec t is used to ho ld info rmatio n abo ut a single attribute in an element. It is no t c o nsidered a true no de value sinc e it is refer-enc ed thro ugh the attributespro perty, rather than the childNodespro p-erty.

✦XMLDOMCDATASection– This o bjec t is similar to the IXMLDOMTexto bjec t, exc ept it c o ntains data that was sto red in a CDATA sec tio n in the XML do c u-ment. The CDATA sec tio n begins with the <[[string and ends with the ]]>

string. Any c harac ters in between the two CDATA delimiters are treated as no rmal text. This lets yo u inc lude any text into a text field, inc luding elements that wo uld no rmally be pro c essed by the XML parser.

✦XMLDOMComment– This o bjec t ho lds an XML c o mment element, whic h is the string o f c harac ters between the .

✦XMLDOMDocumentType– This o bjec t c o ntains info rmatio n abo ut the Do c ument Type Dec laratio ns inc luded in an XML do c ument.

✦XMLDOMElement– This o bjec t c o ntains info rmatio n abo ut a single element in an XML do c ument. If the element in the do c ument c o ntains o ther, nested ele-ments, then the childNodespro perty will c o ntain referenc es to these o bjec ts. The attributespro perty c an be used to find the IXMLDOMAttributeo bjec ts, whic h c o ntain info rmatio n abo ut the attributes fo und in this element.

✦XMLDOMEntity– This o bjec t c o ntains info rmatio n abo ut a parsed o r unparsed entity in the XML do c ument.

✦XMLDOMEntityReference– This o bjec t c o ntains info rmatio n abo ut an entity referenc e in the XML do c ument.

✦XMLDOMNode– This o bjec t is the fundamental o bjec t o f the Do c ument Objec t Mo del. All o f the o ther o bjec ts that c an ac t as a no de in the hierarc hy are derived fro m this o bjec t.

✦XMLDOMNotation– This o bjec t c o ntains no tatio n info rmatio n fro m a Do c ument Type Dec laratio n o r a sc hema.

✦XMLDOMProcessingInstruction– This o bjec t c o ntains pro c essing info rma-tio n fo r the XML do c ument. Fo r example, this o bjec t will sto re the info rmarma-tio n fo und in the <?xml version=”1.0”?>tag that is fo und at the start o f mo st XML do c uments.

(4)

To IXM LDOM or not to IXM LDOM :Microsoft frequently prefixes the node nam es w ith an Iin their im plem entation of the object m odel. The Iprefix is a C+ + con-vention that indicates that the object is a COM Interface, w hich just another object to a Visual Basic program m er.

Other objects

Here are a few o ther o bjec ts that yo u may find interesting. These o bjec ts c anno t be used in plac e o f a no de o bjec t, but o ffer spec ialized suppo rt servic es.

✦XMLDOMDocumentFragment– This o b jec t is used to sto re part o f an XML do c ument. Yo u might find it useful if yo u want to restruc ture an XML o b jec t hierarc hy.

✦XMLDOMImplementation– This o bjec t allo ws yo u to detec t vario us features inc luded in a partic ular implementatio n o f the Do c ument Objec t Mo del.

✦XMLDOMNodeList– This o bjec t is a c o ntainer fo r a c o llec tio n o f no des. This o bjec t is typic ally returned by several metho ds that yo u c an use to searc h fo r spec ific elements in the do c ument hierarc hy.

✦XMLDOMParseError– This o bjec t c o ntains info rmatio n abo ut any erro rs that o c c urred while parsing yo ur XML do c ument.

✦XMLHttpRequest– This o bjec t allo ws yo u to send and rec eive info rmatio n using an HTTP c o nnec tio n.

The XM LDOM Node Object

The XMLDOMNodeo bjec t is the fundamental o bjec t in the Do c ument Objec t Mo del. It fo rms the basis o f all the o ther no de o bjec ts that ho ld yo ur XML do c ument. Eac h o f tho se o bjec ts will inherit the XMLDOMNode’s pro perties and metho ds, to whic h it may add unique pro perties, metho ds, and events.

XM LDOM Node object properties

(5)

459

Chapter 21

✦

Table 21-1

Properties of the XM LDOM Node object

Property Description

attributes An object reference to a node containing the attributes. Returns NULLif this node doesn’t have any attributes.

baseName A Stringvalue containing right side of a fully qualified nam e of the docum ent.

childNodes An object reference to one of several different collections depending on the value of nodeType(see Table 21-2).

dataType A Variantvalue that is either a Stringcontaining the nam e of the data type associated w ith the node or

VT_NULLif no data type is defined.

definition An object reference to a node in the docum ent type definition or schem a, if included.

firstChild An object reference to the first child node of this node. Returns NULLif this node doesn’t have any children.

lastChild An object reference to the last child node of this node. Returns NULLif this node doesn’t have any children.

namespaceURI A Stringcontaining the Universal Resource Identifier (URI) of the nam espace.

nextSibling An object reference to the next sibling of this node. If there are no m ore siblings, then this value is NULL.

nodeName A Stringvalue containing the nam e of the node.

nodeType An enum erated data type containing the type of the node (see Table 21-2).

nodeTypedValue A Stringvalue containing the node’s value in its defined data type.

nodeTypeString A Stringvalue containing a value corresponding to the value of nodeType. See Table 21-2 for the string values that correspond to the nodeTypevalue.

nodeValue A Stringvalue containing the text associated w ith the node.

ownerDocument An object reference to the root DOMDocumentobject or the DOMDocument, w hich created this object.

(6)

Table 21-1

(continued)

parentNode An object reference to the parent object of this node.

parsed A Booleanw hen Truem eans that this node and all of its descendents have been parsed.

prefix A Stringcontaining the nam espace prefix.

previousSibling An object reference to the previous sibling of this node. If this is the first node, then this value w ill be NULL.

specified A Booleanvalue w hen Truem eans that the value w as specified, rather than being derived from a default value in the DTD or schem a.

text A Stringcontaining the text value of the current node and all of its subtrees.

xml A Stringcontaining the XM L statem ents that m ake up

the current docum ent.

XM LDOM Node object methods

The XMLDOMNodeo bjec t has a number o f metho ds that are used to manage the c hild no des asso c iated with it.

Function appendChild (newChild As IXM LDOM Node) as IXM LDOM Node

The appendChildmetho d is used to add a no de o bjec t as a c hild o f the c urrent no de. It returns an o bjec t to the newly added c hild no de. This metho d is the equiva-lent o f c alling insertBefore(newChild, NULL) . newChildis an o bjec t referenc e to a no de, whic h will be added as a c hild to the c urrent no de.

Function cloneNode (deep As Boolean) as IXM LDOM Node

The cloneNodemetho d is used to c reate a c o py o f the c urrent no de. deepis a

(7)

4

NODE_ELEMENT 1 element Represents an elem ent. Can be a child of the

Document, DocumentFragment, EntityReference and Elementnodes. Can have one or m ore Element, Text, Comment, ProcessingInstruction,

CDATASection, and EntityReferencenodes as children.

NODE_ATTRIBUTE 2 attribute Represents an attribute. Referenced though an Entity

node. Can have the Textand the EntityReference nodes as children. Technically, an Attributeis not considered a child of the Elementnode, since it is referenced through the attributesproperty.

NODE_TEXT 3 Text Represents the text content of a tag. Can be a child of the

Attribute, DocumentFragment, Element, and EntityReferencenodes. Cannot have any child nodes.

NODE_CDATA_SECTION 4 cdatasection Represents a CDATA section, w hich is used to escape blocks of text that m ight be recognized as m arkup. Can be a child of the DocumentFragment, EntityReference, and Elementnodes. Cannot have any child nodes.

NODE_ENTITY_REFERENCE 5 Entityreference Represents an entity. Can be a child of the Attribute, DocumentFragment, Element, and EntityReference nodes. Can have the Element,

ProcessingInstruction, Comment, Text, CDATASection, and EntityReferencenodes as children.

NODE_ENTITY 6 Entity Represents an expanded entity. Can be a child of the

DocumentTypenode. Can have other nodes as child nodes.

(8)

6

NODE_PROCESSING_INSTRUCTION 7 processinginstruction Can be a child of the Document, Document Fragment, Element, and EntityReference nodes. Cannot have any child nodes.

NODE_COMMENT 8 comment Represents a com m ent. Can be a child of the

Document, DocumentFragment, Element, and EntityReferencenodes. Cannot have any child nodes.

NODE_DOCUMENT 9 document Represents an XM L docum ent. Cannot be a child

of any other nodes. Can have exactly one child node, w hich can be an Element, a

ProcessingInstruction, a Comment, or a DocumentTypenode.

NODE_DOCUMENT_TYPE 10 Documenttype Represents a docum ent type declaration. Can be a child of the Documentnode. Can have Notation and Entitynodes as child nodes.

NODE_DOCUMENT_FRAGMENT 11 documentfragment Represents a node or subtree w ith a docum ent w ithout being contained w ithin the docum ent. Cannot be a child of any other nodes. Can have Element, ProcessingInstruction, Comment, Text, CDATASection, and EntityReference nodes as child nodes.

NODE_NOTATION 12 notation Represents a notation in the docum ent. Can be a

(9)

463

Chapter 21

✦

Function hasChildNodes ( ) as Boolean

The hasChildNodesmetho d returns Trueif the c urrent no de has c hildren.

Function insertBefore (newChild As ICM LDOM Node, refChild) as

IXM LDOM Node

The insertBeforemetho d is used to add a c hild no de to the c urrent no de. The no de will be inserted befo re the no de spec ified in refChild. An o bjec t referenc e to

newChildwill be returned as the value o f the metho d.

newChildis an o bjec t referenc e to the no de to be added. refChildis an o bjec t ref-erenc e to a no de that is a c hild o f the c urrent no de. If this parameter is NULL, then the no de will be added to the end o f the c o llec tio n.

Function removeChild (childNode as ICM LDOM Node) as

IXM LDOM Node

The removeChildmetho d is used to remo ve the spec ified no de fro m the c urrent no de’s c hild no des. The no de is no t destro yed, so yo u sho uld set the no de to

Nothingto free the no de’s reso urc es if yo u really want to delete it. An o bjec t refer-enc e to the remo ved no de will be returned by the metho d. childNodeis an o bjec t referenc e to the no de to be remo ved.

Function replaceChild (newChild As ICM LDOM Node, oldChild As

ICM LDOM Node) as IXM LDOM Node

The removeChildmetho d is used to replac e an existing no de with a new no de. The metho d will return an o bjec t referenc e to the o ld no de.

newChildis an o bjec t referenc e to a new no de. oldChildis an o bjec t referenc e to o ne o f the c urrent no de’s c hild no des that will be replac ed with newChild.

Function selectNodes (queryString As String) as IXM LDOM NodeList

The selectNodesmetho d searc hes the c urrent o b jec t and its c hildren fo r ele-ments that matc h the spec ified XSL pattern string, and returns them as an

IXMLDOMNodeList. queryStringis a Stringvalue c o ntaining an XSL Pattern q uery.

Function selectSingleNode (queryString As String) as IXM LDOM Node

The selectSingleNodemetho d searc hes the c urrent o bjec t and its c hildren fo r the first element that matc hes the spec ified XSL pattern string, and returns it as an

(10)

Function transformNode (stylesheet As IXM LDOM Node) as String

The transformNodemetho d returns a Stringvalue c o ntaining a fo rmatted XML do c ument using the spec ified XSL style sheet. stylesheetis an o bjec t referenc e to an IXMLDOMNodeo bjec t c o ntaining the ro o t o f the XSL style sheet.

Sub transformNodeToObject (stylesheet As IXM LDOM Node,

outputObject)

The transformNodeToObjectmetho d c reates a DOMDocumentstruc ture c o ntaining the fo rmatted XML do c ument using the spec ified XSL style sheet. stylesheetis an o bjec t referenc e to an IXMLDOMNodeo bjec t c o ntaining the ro o t o f the XSL style sheet. outputObjectis an o bjec t referenc e to a DOMDocumento bjec t whic h will c o ntain the ro o t o bjec t o f the fo rmatted do c ument.

The DOM Document Object

The DOMDocumento bjec t is the fundamental o bjec t in the Do c ument Objec t Mo del. It represents a single XML do c ument.

DOM Document object properties

The DOMDocumento bjec t has all o f the pro perties o f the XMLDOMNodeo bjec t ( see Table 21-1) , plus the additio nal o nes listed in Table 21-3.

Table 21-3

Unique Properties of the

DOMDocument

Object

async A Booleanvalue w hen Truem eans that the Loadm ethod w ill return control to the caller before the load is com plete. You m ust use the readyStateproperty or the

onReadyStateChangeevent to determ ine w hen the load process is finished.

doctype An object reference to an XMLDOMDocumentTypeobject (specified w ith the < !DOCTYPE> tag) containing the docum ent type definition.

documentElement An object reference to the root elem ent of the docum ent.

(11)

465

Chapter 21

✦

namespaces An object reference to an XMLDOMSchemaCacheobject that contains the collection of nam espaces used in this XM L docum ent.

ondataavailable A Booleanvalue, w hen Truem eans that the

ondataavailableevent is enabled.

onreadystatechange A Booleanvalue, w hen Truem eans that the

onreadystatechangeevent is enabled.

ontransformnode A Booleanvalue, w hen Truem eans that the

ontransformnodeevent is enabled.

parseError An object reference to the XMLDOMParseErrorobject, w hich contains inform ation about the last parsing error.

preserveWhiteSpace A Boolean, w hen Truem eans that the parsing process w ill retain the blanks that are included in the XM L source docum ent.

readyState A Longvalue describing the state of the docum ent, w hen loading the docum ent asynchronously (see the async

property). A value of LOADING(1) m eans that the XM L source docum ent is being loaded; a value of LOADED(2) m eans that the docum ent is loaded, but none of the objects are available for access; a value of INTERACTIVE(3) m eans that som e objects are available for use; a value of COMPLETED(4) m eans that the docum ent has been loaded and all objects are available for access. Note that a value of COMPLETEDdoesn’t im ply that the docum ent loaded successfully.

resolveExternals A Booleanvalue, w hen Truem eans that external definitions such as nam espaces, DTD external subsets, and external entity references should be resolved at parse tim e.

schemas An object reference to an XMLSchemaCacheobject containing a list of schem as that should be used w hen loading an XM L docum ent.

url A Stringvalue containing the URL that w as used to load the XM L docum ent.

validateOnParse A Boolean, w hen Truem eans that the docum ent’s structure should be validated during parsing.

Enabled, but impossible: Sim ply setting the ondataavailable, onreadys-tatechange, and ontransformnode properties to True is not sufficient to enable the corresponding events. You m ust declare the Documentobject using the WithEventskeyw ord at the m odule level in your program in order to include code for the events.

(12)

DOM Document object methods

The DOMDocumento bjec t has a number o f unique metho ds that are used to c reate and ac c ess the info rmatio n in an XML do c ument.

Sub Abort ( )

The Abortmetho d will c anc el an async hro no us do wnlo ad. This will return an erro r in the XMLDOMParseErroro bjec t indic ating that the do wnlo ad was abo rted.

Function createAttribute (name As String) as IXM LDOM Attribute

The createAttributemetho d c reates an empty attribute o bjec t with the spec ified name. No te that the newly c reated no de must be added to ano ther no de using the

appendChildmetho d. nameis a Stringvalue c o ntaining the name o f the attribute.

Function createCDATASection (data As String) as

IXM LDOM CDATASection

The createCDATASectionmetho d c reates an empty IXMLDOMCDATASection

o bjec t with the spec ified data. No te that the newly c reated no de must be added to ano ther no de using the appendChildmetho d. datais a Stringvalue that will be sto red in the new o bjec t’s nodeValuepro perty.

Function createNode (type, name As String, namespaceURI As String)

as IXM LDOM Node

The createNodemetho d c reates an empty no de in the do c ument. No te that the newly c reated no de must be added to ano ther no de using the appendChild

metho d. typeis either a Stringvalue c o ntaining the type o f the no de o r an

Integerc o ntaining the numeric value c o rrespo nding to the type o f the no de ( see Table 21-2) nameis a Stringvalue c o ntaining the name o f the no de that will be sto red in the nodeNamepro perty. namespaceURIis a Stringc o ntaining the URI o f the namespac e.

Function createProcessingInstruction (target As String, data As String)

as IXM LDOM ProcessingInstruction

The createProcessingInstructionmetho d c reates an empty

IXMLDOMProcessingInstructiono bjec t with the spec ified data. No te that the newly c reated no de must be added to ano ther no de using the appendChild

metho d. targetis a Stringvalue c o ntaining the name o f the pro c essing instruc -tio n. datais a Stringvalue that will be sto red in the new o bjec t’s nodeValue

(13)

467

Chapter 21

✦

Output version: Use this m ethod to generate the < ?xm l version= ”1.0”?> elem ent at the start of your XM L docum ent. Use xmlas target, and version=”1.0”as

data.

Function createTextNode (data As String) as IXM LDOM TextNode

The createTextNodemetho d c reates an empty TextNo de o bjec t with the spec ified data. No te that the newly c reated no de must be added to ano ther no de using the

appendChildmetho d. datais a Stringvalue that will be sto red in the new o bjec t’s nodeValuepro perty.

Function getElementsByTagName (tagName As String) as

IXM LDOM NodeList

The getElementsByTagNamemetho d searc hes the c urrent o bjec t and its c hildren fo r the spec ified elements and returns them as an IXMLDOMNodeList. tagNameis a

Stringvalue c o ntaining the element name to be fo und. If yo u spec ify an asterisk ( * ) , all elements will be returned.

Function getProperty(name As String)

The getPropertymetho d returns a pro perty value set by the setPropertymetho d.

nameis a Stringvalue c o ntaining the name o f the pro perty. SelectionLanguageis a String value, whic h c an be either Xpath o r XSLPattern. It determines the type o f query that the user spec ifies in the selectNodeso r selectSingleNodemetho ds.

Function load (url As String) as Boolean

The loadmetho d lo ads the spec ified XML do c ument into the DOMDocument, parses it, and then c reates the appro priate c hild o bjec ts to represent the XML do c ument. If the lo ad was suc c essful, this metho d will return True. urlis a Stringvalue c o n-taining a URL that spec ifies the lo c atio n o f the XML do c ument to be lo aded.

Function loadXM L(xmlString As String) as Boolean

The loadXMLmetho d lo ads parses and then c reates the appro priate c hild o bjec ts to represent the XML do c ument spec ified in xmlString. If the lo ad was suc c essful, this metho d will return True. xmlStringis a Stringvalue c o ntaining the XML statements to be lo aded.

Function nodeFromId (idString As String) as IXM LDOM Node

The nodeFromIdmetho d returns the no de, whic h has an ID attribute with the sup-plied value. The ID attribute is suppo sed to appear o nly o nc e in an element, and the value o f eac h ID attribute is suppo sed to be unique within an XML do c ument.

(14)

Sub save (destination)

The savemetho d is used to write the XML to the spec ified lo c atio n. Destinationis a Variantwhic h c an be a Stringvalue c o ntaining a file name o r an ASP Respo nse o bjec t, whic h c an be used to send the do c ument o ver the Internet in a VB IIS Applic atio n.

Sub setProperty(name As String, value)

The setPropertymetho d allo ws yo u to set the value o f the SelectionLanguage

pro perty desc ribed earlier in this c hapter under “Func tio n getPro perty( name As String) .” nameis a Stringvalue c o ntaining the name o f the pro perty, who se value is to be c hanged with the SelectionLanguagepro perty.. valueis the value to be assigned to the pro perty.

Sub validate( )

The validatemetho d verifies the c urrently lo aded do c ument against the c urrently lo aded DTD o r sc hema. Witho ut a DTD o r sc hema, the validate metho d will c ause a run-time erro r.

DOM Document object events

The DOMDocumento bjec t is unique in this o bjec t mo del in that it is the o nly o bjec t to have events. These events assist yo u in pro c essing XML do c uments async hro no usly.

Event ondataavailable ( )

The ondataavailableevent is c alled as so o n as the first o bjec t c o ntaining data is available during an async hro no us lo ad pro c ess. The ondataavailable

event will be c alled as additio nal c hunks o f data bec o me available. No te that the

ondataavailablepro perty must be set to True, and the DOMDocument o bjec t must be dec lared WithEvents, in o rder fo r the event to be fired.

Event onreadystatechange ( )

The onreadystatechangeevent is c alled eac h time the readyStatepro perty c hanges value. No te that the onreadystatechangepro perty must be set to True, and the DOMDocumento bjec t must be dec lared WithEvents, in o rder fo r the event to be fired.

Event Function ontransformnode (nodeCode, nodeData) As Boolean

(15)

469

Chapter 21

✦

c o ntinue, while returning Falsewill abo rt the transfo rmatio n pro c ess. nodeCodeis an o bjec t referenc e to the c urrent no de in the style sheet. nodeDatais an o bjec t refer-enc e to the c urrent no de in the XML do c ument.

Visual Basic, not:This event is not supported in Visual Basic due to the w ay it w as im plem ented.

The XM LDOM Attribute object

The XMLDOMAtributeo bjec t ho lds info rmatio n abo ut a spec ific attribute in an ele-ment. Unlike the o ther no de o bjec ts, the XMLDOMAttributeno des are referenc ed thro ugh the attributespro perty.

XM LDOM Attribute object properties

Table 21-4 lists the unique pro perties asso c iated with the XMLDOMAttributeo bjec t. All o f the pro perties asso c iated with the XMLDOMNodeo bjec t ( see Table 21-1) are also available in this o bjec t.

Table 21-4

Unique Properties of the XM LDOM Node object

Name A Stringvalue containing the nam e of the attribute.

Value A Stringcontaining the attribute’s value.

XM LDOM Attribute object methods

The XMLDOMAttributeo bjec t has no unique metho ds. It inherits all o f the metho ds fo und in the XMLDOMNodeo bjec t.

The XM LDOM CDATASection Object

The XMLDOMCommento bjec t ho lds info rmatio n abo ut a CDATA sec tio n in yo ur XML do c ument.

(16)

XM LDOM CDATASection object properties

Table 21-5 lists the unique pro perties asso c iated with the XMLDOMCDATASection

o bjec t. All o f the pro perties listed in the XMLDOMNodeo bjec t ( see Table 21-1) are also available fo r this o bjec t.

Table 21-5

Unique Properties of the XM LDOM CDATASection Object

Data A Stringvalue containing the characters from the CDATA section of the XM L docum ent.

Length A Longvalue containing the num ber of characters in data.

XM LDOM CDATASection object methods

The XMLDOMCDATASectiono bjec t has two unique metho ds that are used to ac c ess the info rmatio n fro m a CDATA sec tio n in yo ur XML do c ument. All o f the metho ds fo und in the XMLDOMNodeo bjec t are available fo r this o bjec t as well.

Function splitText (offset As Long) as IXM LDOM Text

The splitTextmetho d splits the no de into two no des at the spec ified o ffset fro m the beginning o f the text and auto matic ally inserts the new no de into the do c ument hierarc hy immediately fo llo wing the c urrent no de. offsetis a Longvalue c o ntain-ing the lo c atio n where the split will take plac e. Spec ifyntain-ing an o ffset value o f zero will mo ve all o f the text in the c urrent no de to the new no de.

Function substringData (offset As Long, count As Long) as String

The substringDatametho d extrac ts a blo c k o f text fro m the no de. offsetis a

Longvalue c o ntaining the lo c atio n where the extrac tio n will begin. The first c harac -ter in the string has an o ffset o f zero . countis a Longc o ntaining the number o f c harac ters to be extrac ted.

The XM LDOM Comment Object

(17)

471

Chapter 21

✦

XM LDOM Comment object properties

Table 21-6 lists the pro perties asso c iated with the XMLDOMCommento bjec t. It also inherits the pro perties fro m the XMLDOMNodeo bjec t ( see Table 21-1) .

Table 21-6

Unique Properties of the XM LDOM Comment Object

Data A Stringvalue containing the characters in the Com m ent section of the XM L docum ent.

Length A Longvalue containing the num ber of characters in data.

XM LDOM Comment object methods

The XMLDOMCommento bjec t has a metho d that yo u c an use to extrac t info rmatio n fro m a Co mment sec tio n in yo ur XML do c ument. The metho ds available in the

XMLDOMNodeo bjec t are also available in this o bjec t.

Function substringData (offset As Long, count As Long) as String

Longvalue c o ntaining the lo c atio n where the extrac tio n will begin. The first c harac -ter in the string has an o ffset o f zero . countis a Longc o ntaining the number o f c harac ters to be extrac ted.

The XM LDOM DocumentType Object

The XMLDOMDocumentTypeo b jec t ho lds info rmatio n ab o ut a do c ument type dec laratio n.

XM LDOM DocumentType object properties

Table 21-7 lists the unique pro perties asso c iated with the XMLDOMDocumentType

(18)

Table 21-7

Unique Properties of the XM LDOM Node Object

Entities An object reference to an XMLDOMNameNodeMapcontaining the collection of entities used in the docum ent type declaration.

Name A Stringvalue containing the nam e of the docum ent type.

Notations An object reference to an XMLDOMNameNodeMapcontaining the collection of XMLDOMNotationobjects.

XM LDOM DocumentType object methods

The XMLDOMDocumentTypeo bjec t has no unique metho ds. It inherits all o f the metho ds fo und in the XMLDOMNodeo bjec t.

The XM LDOM Element Object

The XMLDOMElemento b jec t ho lds info rmatio n ab o ut an entity fro m yo ur XML do c ument.

XM LDOM Element object properties

The unique pro perty o f the XMLDOMElemento bjec t is tagName, whic h is a String

value c o ntaining the name o f the tag that is used to identify the element. The

XMLDOMElemento bjec t also inherits the pro perties fro m the XMLDOMNodeo bjec t ( see Table 21-1) .

XM LDOM Element object methods

The XMLDOMElemento bjec t pro vides several metho ds that make it easy to ac c ess the info rmatio n fro m the attributes asso c iated with this o bjec t. No te that the meth-o ds available in the XMLDOMNodeo bjec t ( see Table 21-1) are also available in this o bjec t.

Function getAttribute (name as String) as Variant

The getAttributemetho d returns a Stringc o ntaining the value o f the attribute. An empty string means that the attribute do esn’t have a spec ified o r default value.

(19)

473

Chapter 21

✦

Function getAttributeNode (name as String) as IXM LDOM Attribute

The getAttributeNodemetho d returns a referenc e to an XMLDOMAttribute

o bjec t c o ntaining the spec ified attribute. nameis a Stringvalue c o ntaining the name o f the attribute.

Sub normalize( )

The normalizemetho d c o mbines all o f the text no des belo w this o bjec t into no r-mal fo rm, where eac h text no de is separated by an element, a c o mment, a pro c ess-ing instruc tio n, a CDATA sec tio n, o r an entity referenc e. Yo u c an do the same thess-ing by saving the do c ument to a disk file, deleting all o f the o bjec ts belo w the

DOMDocumento bjec t, and lo ading the do c ument bac k fro m the disk file.

Sub setAttribute (name as String, value)

The setAttributemetho d assigns a new value to an attribute. If the attribute do esn’t exist, it will auto matic ally be c reated fo r yo u. nameis a Stringvalue c o n-taining the name o f the attribute.valueis a Variantvalue c o ntaining the value to be assigned to the attribute.

Function setAttributeNode (DOM Attribute as IXM LDOM Attribute) as

IXM LDOM Attribute

The setAttributeNodemetho d is used to c reate o r replac e an attribute no de in the do c ument hierarc hy. It will return Nullif the attribute didn’t exist, o r it will return an o bjec t po inter to the o ld attribute’s no de. DOMAttributeis an o bjec t ref-erenc e to an XMLDOMAttributeo bjec t that c o ntains the new attribute.

The XM LDOM Entity Object

The XMLDOMEntityo b jec t ho ld s info rmatio n ab o ut an entity fro m yo ur XML d o c ument.

XM LDOM Entity object properties

(20)

Table 21-8

Unique Properties of the XM LDOM Entity Object

notationName A Stringvalue containing the nam e of the notation, if the entity is unparsed or an em pty string once the entity has been parsed.

publicId A Stringcontaining the public identifier associated w ith the entity.

systemId A Stringcontaining the system identifier associated w ith the entity. If the system identifier isn’t specified, this property w ill contain the em pty string.

XM LDOM Entity object methods

The XMLDOMEntityo bjec t has no unique metho ds. It inherits all o f the metho ds fo und in the XMLDOMNodeo bjec t.

The XM LDOM EntityReference Object

The XMLDOMEntityReferenceo b jec t ho lds info rmatio n ab o ut an entity fro m yo ur XML do c ument. This o b jec t is c reated b ased o n the info rmatio n fro m the

XMLDOMEntityo b jec t. Due to the nature o f the XML parser inc luded in the o b jec t lib rary, external entities may no t b e parsed and expanded in their o wn o b jec ts until they are needed, whic h means that two different o b jec ts are needed to ho ld the info rmatio n.

No difference: The XMLDOMEntityReferenceobject doesn’t have any unique properties, m ethods, or events, w hen com pared to the XMLDOMNodeobject. All of the standard properties and m ethods of the XMLDOMNodeobject are available in this object.

The XM LDOM Notation Object

The XMLDOMNotationo bjec t ho lds info rmatio n abo ut a no tatio n that was dec lared in the data type dec laratio n o r sc hema sec tio n o f yo ur XML do c ument.

(21)

475

Chapter 21

✦

XM LDOM Notation object properties

Table 21-9 lists the unique pro perties o f the XMLDOMNotationo bjec t. This o bjec t also inherits all o f the pro perties fro m the XMLDOMNodeo bjec t.

Table 21-9

Unique Properties of the XM LDOM Notation Object

publicId A Stringvalue containing the public identifier associated w ith the notation.

systemId A Stringcontaining the system identifier associated w ith the notation. If the system identifier isn’t specified, this property w ill contain the em pty string.

XM LDOM Notation object methods

The XMLDOMNotationo bjec t has no unique metho ds. It inherits all o f the metho ds fo und in the XMLDOMNodeo bjec t ( see Table 21-1) .

The XM LDOM ProcessingInstruction Object

The XMLDOMProcessingInstructiono bjec t c o ntains pro c essing direc tives, suc h as the <?xml version=1.0?>.

XM LDOM ProcessingInstruction object properties

Table 21-10 lists the unique pro perties o f the XMLDOMProcessingInstruction

o bjec t. This o bjec t also inherits all o f the pro perties fro m the XMLDOMNodeo bjec t ( see Table 21-1) .

XM LDOM ProcessingInstruction object methods

(22)

Table 21-10

Unique Properties of the XM LDOM ProcessingInstruction Object

data A Stringvalue containing the data associated w ith the processing instruction. In other w ords, this w ould be the version=”1.0”part of the processing instruction. This value is identical to that in the

nodeValueproperty.

target A Stringcontaining the application that contains the processing instruction.

For exam ple, this w ould be xmlfrom the <?xml version=”1.0”?>

processing instruction.

The XM LDOM Text Object

The XMLDOMTexto bjec t ho lds info rmatio n abo ut the text value asso c iated with an

XMLDOMElemento r XMLDOMAttributeno de.

XM LDOM Text object properties

Table 21-11 lists the unique pro perties asso c iated with the XMLDOMTexto bjec t. All o f the pro perties listed in the XMLDOMNodeo bjec t are also available fo r this o bjec t.

Table 21-11

Unique Properties of the XM LDOM Text Object

data A Stringvalue containing the text characters that m ake up the value of an elem ent or an attribute.

length A Longvalue containing the num ber of characters in data.

XM LDOM Text object methods

The XMLDOMTexto bjec t inc ludes a ric h set o f metho ds to manipulate the data sto red in the no de. It also inc ludes all o f the metho ds fo und in the XMLDOMNode

(23)

477

Chapter 21

✦

Sub appendData (data as String)

The appendDatametho d adds the spec ified string value to the end o f the existing data already in the no de. datais a Stringvalue c o ntaining the new info rmatio n to be added to the no de’s value.

Sub deleteData (offset as Long, count as Long)

The deleteDatametho d remo ves the spec ified number c harac ters fro m the no de starting with the spec ified lo c atio n. offsetis a Longvalue c o ntaining the lo c atio n where the c harac ters will be deleted. The first c harac ter in the string has an o ffset o f zero . countis a Longc o ntaining the number o f c harac ters to be deleted.

Sub insertData (offset as Long, data as String)

The insertDatametho d inserts the spec ified data into the data already starting with the spec ified lo c atio n. offsetis a Longc o ntaining the lo c atio n where the c harac ters will be inserted. The first c harac ter in the string has an o ffset o f zero .

datais a Stringc o ntaining the c harac ters to be added.

Sub replaceData (offset as Long, count as Long, data as String)

The replaceDatametho d deletes the spec ified number o f c harac ters starting at the spec ified lo c atio n, then inserts the spec ified data starting at the same lo c atio n.

offsetis a Longc o ntaining the lo c atio n where the c harac ters will be replac ed. The first c harac ter in the string has an o ffset o f zero . countis a Longc o ntaining the number o f c harac ters to be deleted. datais a Stringc o ntaining the c harac ters to be added.

Function splitText (offset as Long) as IXM LDOM Text

The splitTextmetho d splits the no de into two no des at the spec ified o ffset fro m the beginning o f the text, and auto matic ally inserts the new no de into the do c u-ment hierarc hy immediately fo llo wing the c urrent no de. offsetis a Longc o ntain-ing the lo c atio n where the split will take plac e. Spec ifyntain-ing an o ffset value o f zero will mo ve all o f the text in the c urrent no de to the new no de.

Function substringData (offset as Long, count as Long) as String

(24)

The XM LDOM ParseError Object

The XMLDOMParseErroro bjec t c o ntains info rmatio n abo ut the first erro r enc o un-tered while parsing yo ur XML do c ument.

XM LDOM ParseError object properties

Table 21-12 lists the pro perties o f the XMLDOMParseErroro bjec t.

Table 21-12

Properties of the XM LDOM ParseError object

ErrorCode A Longvalue containing the error code.

Filepos A Longcontaining the absolute position in the file w here the error occurred.

Line A Longcontaining the line num ber w here the error occurred.

Linepos A Longcontaining the position in the line w here the error occurred.

Reason A Stringvalue containing a text description of the error.

SrcText A Stringcontaining the line w ith the error.

url A Stringcontaining the URL of the docum ent w ith the error.

XM LDOM ParseError bject methods

The XMLDOMParseErroro bjec t do esn’t have any metho ds.

The XM LHttpRequest Object

(25)

479

Chapter 21

✦

XM LHttpRequest object properties

Table 21-13 lists the pro perties o f the XMLHttpRequesto bjec t.

Table 21-13

Properties of the XM LHttpRequest Object

onreadystatechange An object reference to an event handler in a scripting language.

readyState A Longvalue describing the state of the transport, w hen loading the docum ent asynchronously (see the async

property). A value of UNINITIALIZED(0) m eans that the object has been created but nothing has been transferred. A value of LOADING(1) m eans that the source docum ent is being loaded; a value of LOADED(2) m eans that the docum ent is loaded, but none of the objects in the docum ent hierarchy are available for access; a value of INTERACTIVE(3) m eans that som e objects are available for use; a value of COMPLETED(4) m eans that the docum ent has been loaded and all objects are available for access. Note that a value of COMPLETEDdoesn’t im ply that the docum ent loaded successfully.

responseBody A Variantvalue containing the response to the HTTP request.

responseStream An object reference to a Streamobject containing the raw data from the response to the HTTP request.

responseText A Stringvalue containing the response to the HTTP request.

responseXML An object reference to a DOMDocumentobject containing the parsed XM L docum ent that w as received in response to the HTTP request.

status A Longcontaining the HTTP status code returned by the HTTP server.

statusText A Stringcontaining the HTTP line status.

XM LHttpRequest object methods

(26)

Sub abort( )

The abortmetho d terminates an ac tive HTTP request.

Function getAllResponseHeaders ( ) as String

The getAllResponseHeadersmetho d returns the header info rmatio n fro m the HTTP result as a single string. Eac h header is separated by a c arriage return/ line feed pair (vbCrLf) .

Function getResponseHeader (bstrHeader as String) as String

The getResponseHeadermetho d returns the spec ified header fro m the HTTP respo nse where bstrHeaderis a Stringvalue c o ntaining the partic ular header yo u wish to retrieve.

Sub open(bstrM ethod as String, bstrUrl As String, [varAsync],

[bstrUser], [bstrPassword])

The openmetho d initializes an HTTP request. After the request is initialized, the

sendmetho d must be used to transfer the do c ument and wait fo r the respo nse.

bstrMethodis a Stringvalue that identifies the HTTP transfer metho d. This is usually o ne o f the fo llo wing: GET, POST, PUT, o r PROPFIND. bstrUrlis a String

c o ntaining the URL that will be used to pro c ess the request. varAsyncis a

Booleanvalue when Truemeans that the c all is async hro no us. If this value isn’t spec ified, it will default to True. bstrUseris a Stringc o ntaining the userid to lo g o nto the Web server. If this parameter is missing and the Web server requires a userId and passwo rd to lo g o n, the user will be pro mpted fo r this info rmatio n.

bstrPasswordis a Stringc o ntaining the passwo rd asso c iated with bstrUserid.

Sub send ([varBody])

The sendmetho d transmits the request to the remo te ho st and o ptio nally waits fo r the ho st’s respo nse if the user spec ified Falsefo r varAsynco n the openmetho d.

varBodyis a Variantvalue c o ntaining the do c ument to be sent. If this parameter isn’t spec ified, then the c urrent do c ument is transmitted.

Sub setRequestHeader(bstrHeader as String, bstrValue as String)

The setRequestHeader metho d sets the value o f the vario us header fields befo re the do c ument request is sent. bstrHeaderis a Stringvalue c o ntaining the header to be set. No te that the trailing c o lo n ( :) o n the header sho uld no t be spec ified.

(27)