Libxml2 +Overview

This section describes the libxml2 component which is a wrapper for the +standard libxml2 C library.

Purpose

The libxml2 component provides XML processing, +parsing and validation APIs. You can call its C functions directly or use +the C++ wrapper.

Required background

The libxml2 component is based +on the standard libxml2 library.

Architecture

The libxml2 component is the core +of the XML collection. Two other components rely on it: the XML +Framework and the XML +DOM Engine.

+ Package diagram for the libxml2 component + +

The libxml2 sub-component provides direct access to the C API of +the standard libxml2 library.

The Utilities sub-component provides +object-oriented access to the C functions: it also implements the resource +management and error handling capabilities of the Symbian Platform.

If +your Symbian Platform build does not include the libxml2 component, the XML +DOM Engine and the libxml2 SAX parser plug-in are automatically excluded.

+ +

APIs

The XMLEngPushL() function +opens and initializes the libxml2 library parser. The XMLEngPopAndClose() function +closes the library parser and frees its resources. You must call the XMLEngPushL() function +before any parsing and serialisation operations, and call the XMLEngPopAndClose() function +when these operations are completed.

The following table lists the +most relevant wrapper classes of the libxml2 library. High-level classes are +in the XML DOM Engine component.

+ + + +API +Description + + + + +

xmlGlobalState

Global data providing access to most of the libxml2 library: settings, +function pointers, and so on. Available through TLS

+ + +

TXmlEngString

General-purpose string: pointer-sized object containing a zero-terminated +UTF-8 string.

+ + +

TXmlEngConstString

Read-only version of TXmlEngString.

+ + + +

The following table lists the most relevant C structures of the +libxml2 library.

+ + + +API +Description + + + + +

_xmlDoc

Document. Provides access to the tree of nodes.

+ + +

_xmlNode

Node. Provides access to its children and chain of attributes.

+ + +

_xmlAttribute

Attribute.

+ + +

_xmlElement

Element.

+ + +

xmlAttributeType::_xmlElementContent

Container for the contents of an element.

+ + +

_xmlSchema and _xmlDtd

Validation trees. These structures have no C++ wrappers.

+ + +

_xmlXPathParserContext

XPath evaluation context.

+ + + +

Typical uses

When porting existing software, use +the C functions of the standard libxml2 library and refer to the libxml2 Reference Manual for more information.

To +take advantage of the standard types and exception handling provided by the +Symbian Platform, use the C++ APIs.