Parsing -the XML Data

Parsing -the XML Data -

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.

Introduction

In order to parse XML data, an instance -of the parser must be created. Two types of constructors exist, one type takes -a MXMLDtd 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.

All of the -constructors take a MMDXMLParserObserver 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.

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.

Procedure

Generate a DOM tree from XML data.
Extract the data from the DOM tree.

Generate a DOM -tree from XML data

The following are the steps required to parse -XML data and get the DOM tree:

Call CMDXMLParser::ParseFile(), -passing in the filename of the XML document to be parsed.

When the -parsing is complete, the parser calls the observer's ParseFileCompleteL() function. -This function must initiate the handling of the DOM tree that has been generated -by the parser.
Call CMDXMLParser::DetachXMLDoc() to -take ownership of the parsed DOM tree.
Call CMDXMLDocument::DocumentElement() to -get the root element of the DOM tree.

Extract data from -the DOM tree

The DOM tree is made up of CMDXMLNode objects. -The document element that is returned by the final step of the previous section -is an example of a CMDXMLNode.

Use the following -functions to navigate the DOM tree:

CMDXMLNode::HasChildNodes()
CMDXMLNode::FirstChild()
CMDXMLNode::LastChild()
CMDXMLNode::NextSibling()
CMDXMLNode::PreviousSibling()

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 CMDXMLNode::NodeType(). -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:

CMDXMLComment: -Comment data.
CMDXMLProcessingInstruction: -Processing instruction data.
CMDXMLText: -Text data.
CMDXMLElement: -Element data including attribute name/value pairs.
CMDXMLDocumentElement: -Represents the root element in the DOM tree. This is the first node that is -accessible after parsing is complete.

-SMIL Parser -Overview -Composing -the XML Data + + + + + +Parsing +the XML Data +

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.

Introduction

In order to parse XML data, an instance +of the parser must be created. Two types of constructors exist, one type takes +a MXMLDtd 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.

All of the +constructors take a MMDXMLParserObserver 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.

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.

Procedure

Generate a DOM tree from XML data.
Extract the data from the DOM tree.

Generate a DOM +tree from XML data

The following are the steps required to parse +XML data and get the DOM tree:

Call CMDXMLParser::ParseFile(), +passing in the filename of the XML document to be parsed.

When the +parsing is complete, the parser calls the observer's ParseFileCompleteL() function. +This function must initiate the handling of the DOM tree that has been generated +by the parser.
Call CMDXMLParser::DetachXMLDoc() to +take ownership of the parsed DOM tree.
Call CMDXMLDocument::DocumentElement() to +get the root element of the DOM tree.

Extract data from +the DOM tree

The DOM tree is made up of CMDXMLNode objects. +The document element that is returned by the final step of the previous section +is an example of a CMDXMLNode.

Use the following +functions to navigate the DOM tree:

CMDXMLNode::HasChildNodes()
CMDXMLNode::FirstChild()
CMDXMLNode::LastChild()
CMDXMLNode::NextSibling()
CMDXMLNode::PreviousSibling()

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 CMDXMLNode::NodeType(). +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:

CMDXMLComment: +Comment data.
CMDXMLProcessingInstruction: +Processing instruction data.
CMDXMLText: +Text data.
CMDXMLElement: +Element data including attribute name/value pairs.
CMDXMLDocumentElement: +Represents the root element in the DOM tree. This is the first node that is +accessible after parsing is complete.

+SMIL Parser +Overview +Composing +the XML Data

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