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<concept id="GUID-2468D736-9F95-5412-B687-765D630651C7" xml:lang="en"><title>Parsing

the XML Data</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>XML Parser is used to convert XML data to and from the DOM tree structure.The

end result of the XML parsing is a DOM tree structure. In the case of SMIL,

the player can use this DOM tree to render the slides. </p>

<section><title>Introduction</title> <p>In order to parse XML data, an instance

of the parser must be created. Two types of constructors exist, one type takes

a <xref href="GUID-F294DC1C-D762-3CF7-BB64-18E742BA6EAA.dita"><apiname>MXMLDtd</apiname></xref> object, while the other does not. If a DTD object

is supplied, then the parser validates the XML according to that DTD. If no

DTD class is provided, then no validation takes place. </p> <p>All of the

constructors take a <xref href="GUID-50F526AD-8471-35DD-8730-9BFB3956537C.dita"><apiname>MMDXMLParserObserver</apiname></xref> parameter. This

interface is usually implemented by the owning class which then passes itself

to the parser constructor. This interface exists so that the parser can notify

its owner when parsing is complete. </p> <p>The way in which the DOM tree

is used varies depending on the type of XML and even between different clients

of the same type of XML. Different SMIL players may walk the DOM tree in slightly

different ways; however several functions are likely to be used by all XML

clients. </p> </section>

<section><title>Procedure</title> <ol id="GUID-D137D73E-FD40-5698-A415-EE9B7D1A113A">

<li id="GUID-253A51FB-7AF2-5EC2-9391-020B9B59524F"><p> <xref href="GUID-2468D736-9F95-5412-B687-765D630651C7.dita#GUID-2468D736-9F95-5412-B687-765D630651C7/GUID-8BC5C4C3-B4D2-5754-B608-0F840F546FDA">Generate a DOM tree from XML data</xref>. </p> </li>

<li id="GUID-F8A280E4-4B82-5914-A5C5-1AFEB55746BD"><p> <xref href="GUID-2468D736-9F95-5412-B687-765D630651C7.dita#GUID-2468D736-9F95-5412-B687-765D630651C7/GUID-EFE7D031-72EE-597A-BE9B-8E3288DD80E1">Extract the data from the DOM tree</xref>. </p> </li>

</ol> <p id="GUID-8BC5C4C3-B4D2-5754-B608-0F840F546FDA"><b>Generate a DOM

tree from XML data</b> </p> <p>The following are the steps required to parse

XML data and get the DOM tree: </p> <ol id="GUID-0A1120E9-B57E-5216-B2D6-3E9FCF8AA7E2">

<li id="GUID-24024261-44FB-5517-8321-86CE292958E1"><p>Call <xref href="GUID-3AF26F84-F4C0-312D-9ABD-1C6EC0BD1675.dita#GUID-3AF26F84-F4C0-312D-9ABD-1C6EC0BD1675/GUID-AA06AF37-7C4F-376C-9A83-CC87C2BC3A75"><apiname>CMDXMLParser::ParseFile()</apiname></xref>,

passing in the filename of the XML document to be parsed. </p> <p>When the

parsing is complete, the parser calls the observer's <xref href="GUID-A0FB1AC0-9971-3387-8419-98962024A3C6.dita"><apiname>ParseFileCompleteL()</apiname></xref> function.

This function must initiate the handling of the DOM tree that has been generated

by the parser. </p> </li>

<li id="GUID-215D2D49-25FD-580C-95CF-D9DA0D5936BB"><p>Call <xref href="GUID-3AF26F84-F4C0-312D-9ABD-1C6EC0BD1675.dita#GUID-3AF26F84-F4C0-312D-9ABD-1C6EC0BD1675/GUID-727267CE-EAF7-31FF-8BFC-41137D33AB86"><apiname>CMDXMLParser::DetachXMLDoc()</apiname></xref> to

take ownership of the parsed DOM tree. </p> </li>

<li id="GUID-BDEF9D19-4D4D-5C4B-8F9F-A7531CE8CA36"><p>Call <xref href="GUID-2A597821-BF7F-379A-A32C-99CF9B5CDFAA.dita#GUID-2A597821-BF7F-379A-A32C-99CF9B5CDFAA/GUID-C6D821B2-7571-305C-A6D8-1B031BAE3774"><apiname>CMDXMLDocument::DocumentElement()</apiname></xref> to

get the root element of the DOM tree. </p> </li>

</ol> <p id="GUID-EFE7D031-72EE-597A-BE9B-8E3288DD80E1"><b>Extract data from

the DOM tree</b> </p> <p>The DOM tree is made up of <xref href="GUID-8BBCB6A5-A133-3BDD-8614-E5E2F1FED7E5.dita"><apiname>CMDXMLNode</apiname></xref> objects.

The document element that is returned by the final step of the previous section

is an example of a <xref href="GUID-8BBCB6A5-A133-3BDD-8614-E5E2F1FED7E5.dita"><apiname>CMDXMLNode</apiname></xref>. </p> <p>Use the following

functions to navigate the DOM tree: </p> <ul>

<li id="GUID-11C61DEB-154C-5C5E-9C29-A516A746EA1F"><p> <xref href="GUID-8BBCB6A5-A133-3BDD-8614-E5E2F1FED7E5.dita#GUID-8BBCB6A5-A133-3BDD-8614-E5E2F1FED7E5/GUID-9FF00918-EF74-3B93-BD70-55CB984A3F91"><apiname>CMDXMLNode::HasChildNodes()</apiname></xref>  </p> </li>

<li id="GUID-9087B094-CC80-5905-9FB6-68E4DAC2E54C"><p> <xref href="GUID-8BBCB6A5-A133-3BDD-8614-E5E2F1FED7E5.dita#GUID-8BBCB6A5-A133-3BDD-8614-E5E2F1FED7E5/GUID-361BF090-E839-3A30-90ED-E87BEB315082"><apiname>CMDXMLNode::FirstChild()</apiname></xref>  </p> </li>

<li id="GUID-CD28E350-86E7-5AFD-BEFA-6C2A17114F93"><p> <xref href="GUID-8BBCB6A5-A133-3BDD-8614-E5E2F1FED7E5.dita#GUID-8BBCB6A5-A133-3BDD-8614-E5E2F1FED7E5/GUID-4F329EBA-3AB0-3D9B-9FDE-672E04BE960C"><apiname>CMDXMLNode::LastChild()</apiname></xref>  </p> </li>

<li id="GUID-AF6D7232-C12E-50F5-AE8A-C1AF824228F7"><p> <xref href="GUID-8BBCB6A5-A133-3BDD-8614-E5E2F1FED7E5.dita#GUID-8BBCB6A5-A133-3BDD-8614-E5E2F1FED7E5/GUID-8269D952-2CB1-3887-BE6D-EF85C82F8479"><apiname>CMDXMLNode::NextSibling()</apiname></xref>  </p> </li>

<li id="GUID-37172D30-E4C5-596E-99C6-9BE820BDF532"><p> <xref href="GUID-8BBCB6A5-A133-3BDD-8614-E5E2F1FED7E5.dita#GUID-8BBCB6A5-A133-3BDD-8614-E5E2F1FED7E5/GUID-DE9AC9D0-CD7F-39DA-A8F4-E4A4F744BA07"><apiname>CMDXMLNode::PreviousSibling()</apiname></xref>  </p> </li>

</ul> <p>Once a child or sibling node has been located, it is necessary to

cast it to the specific type. The type can be identified by calling <xref href="GUID-8BBCB6A5-A133-3BDD-8614-E5E2F1FED7E5.dita#GUID-8BBCB6A5-A133-3BDD-8614-E5E2F1FED7E5/GUID-25D83285-9D7A-3D84-BE06-F889FFDAB262"><apiname>CMDXMLNode::NodeType()</apiname></xref>.

The following types of node might exist in a parsed DOM tree. Once the type

has been identified, they must be cast to one of the following: </p> <ul>

<li id="GUID-A871CB40-BFCD-512F-8273-DB71509E6D9F"><p> <xref href="GUID-20E3DBF1-98CB-3B4D-AF93-38061F1E827A.dita"><apiname>CMDXMLComment</apiname></xref>:

Comment data. </p> </li>

<li id="GUID-A97D0934-C348-54CE-9538-BB7820924C58"><p> <xref href="GUID-7360D100-1F97-3F46-950E-E3A8CE3E8E1E.dita"><apiname>CMDXMLProcessingInstruction</apiname></xref>:

Processing instruction data. </p> </li>

<li id="GUID-AEE0A2F8-844E-5170-A466-9542650C2EF0"><p> <xref href="GUID-92E6AF07-A178-3A01-9FA5-16EB78323420.dita"><apiname>CMDXMLText</apiname></xref>:

Text data. </p> </li>

<li id="GUID-F5676BD0-08AE-5378-AF63-3D06764428AD"><p> <xref href="GUID-DF432AB6-7895-30E8-9B4B-378E61A7A901.dita"><apiname>CMDXMLElement</apiname></xref>:

Element data including attribute name/value pairs. </p> </li>

<li id="GUID-78715F02-52BF-5FB3-B3FC-8D69A97C7C05"><p> <xref href="GUID-B87073A7-36C3-3B1A-ABE7-C1035A21C8C5.dita"><apiname>CMDXMLDocumentElement</apiname></xref>:

Represents the root element in the DOM tree. This is the first node that is

accessible after parsing is complete. </p> </li>

</ul> </section>

</conbody><related-links>

<link href="GUID-FDC0004A-A2EE-5B73-9E2D-B6864C600AF9.dita"><linktext>SMIL Parser

Overview</linktext></link>

<link href="GUID-99CC6D00-DC3E-51C2-8152-060FB80F5FCD.dita"><linktext>Composing

the XML                 Data</linktext></link>

</related-links></concept>