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     7     Nokia Corporation - initial contribution.

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    10 <!DOCTYPE concept

    11   PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

    12 <concept id="GUID-33D50AB9-AFA8-521F-8A85-031C24EA7D25" xml:lang="en"><title>Libxml2

    13 Overview</title><prolog><metadata><keywords/></metadata></prolog><conbody>

    14 <p>This section describes the libxml2 component which is a wrapper for the

    15 standard libxml2 C library. </p>

    16 <section id="GUID-F78E0EE2-A612-4AB4-9EBF-09B220780574"><title>Purpose</title> <p>The libxml2 component provides XML processing,

    17 parsing and validation APIs. You can call its C functions directly or use

    18 the C++ wrapper. </p> </section>

    19 <section id="GUID-B4508A67-D97E-4EEA-801A-0AB808B695C8"><title>Required background</title> <p>The libxml2 component is based

    20 on the standard <xref href="http://xmlsoft.org/" scope="external">libxml2</xref> library. </p> </section>

    21 <section id="GUID-4B29685C-200B-42F0-8DD1-C93242843C63"><title>Architecture</title> <p>The libxml2 component is the core

    22 of the XML collection. Two other components rely on it: the <xref href="GUID-F79E4F18-19E2-577E-8409-8B82BD48AC66.dita">XML

    23 Framework</xref> and the <xref href="GUID-5ACFA8E4-3C4B-5851-A43E-9FA72D0B8403.dita">XML

    24 DOM Engine</xref>. </p> <fig id="GUID-4EE5466D-6370-5ED5-9BAA-838F5413AAE5">

    25 <title>              Package diagram for the libxml2 component            </title>

    26 <image href="GUID-873186CE-9723-558F-9C7E-0CEE607F076C_d0e429410_href.png" placement="inline"/>

    27 </fig> <p>The libxml2 sub-component provides direct access to the C API of

    28 the standard libxml2 library. </p> <p>The Utilities sub-component provides

    29 object-oriented access to the C functions: it also implements the resource

    30 management and error handling capabilities of the Symbian Platform. </p> <p>If

    31 your Symbian Platform build does not include the libxml2 component, the XML

    32 DOM Engine and the libxml2 SAX parser plug-in are automatically excluded. </p> </section>

    33 

    34 <section id="GUID-BB2FC62C-E8AB-42CF-BFC1-FC7CA5EDB9DC"><title>APIs</title> <p>The <xref href="GUID-321A32BB-75B1-38B4-A8F5-BF69D1F041FD.dita"><apiname>XMLEngPushL()</apiname></xref> function

    35 opens and initializes the libxml2 library parser. The <xref href="GUID-64E53D09-2F54-3188-A1D4-F541BDC40240.dita"><apiname>XMLEngPopAndClose()</apiname></xref> function

    36 closes the library parser and frees its resources. You must call the <xref href="GUID-321A32BB-75B1-38B4-A8F5-BF69D1F041FD.dita"><apiname>XMLEngPushL()</apiname></xref> function

    37 before any parsing and serialisation operations, and call the <xref href="GUID-64E53D09-2F54-3188-A1D4-F541BDC40240.dita"><apiname>XMLEngPopAndClose()</apiname></xref> function

    38 when these operations are completed. </p> <p>The following table lists the

    39 most relevant wrapper classes of the libxml2 library. High-level classes are

    40 in the <xref href="GUID-5ACFA8E4-3C4B-5851-A43E-9FA72D0B8403.dita">XML DOM Engine</xref> component. </p> <table id="GUID-9A8FA78F-CF35-5897-AD8E-B35B7CFF63D9">

    41 <tgroup cols="2"><colspec colname="col0"/><colspec colname="col1"/>

    42 <thead>

    43 <row>

    44 <entry>API</entry>

    45 <entry>Description</entry>

    46 </row>

    47 </thead>

    48 <tbody>

    49 <row>

    50 <entry><p> <xref href="GUID-1DA29392-2F71-36CA-865F-B6616E1506F8.dita"><apiname>xmlGlobalState</apiname></xref>  </p> </entry>

    51 <entry><p>Global data providing access to most of the libxml2 library: settings,

    52 function pointers, and so on. Available through TLS </p> </entry>

    53 </row>

    54 <row>

    55 <entry><p> <xref href="GUID-2B22200A-55E0-3428-94FE-332224003D68.dita"><apiname>TXmlEngString</apiname></xref>  </p> </entry>

    56 <entry><p>General-purpose string: pointer-sized object containing a zero-terminated

    57 UTF-8 string. </p> </entry>

    58 </row>

    59 <row>

    60 <entry><p> <xref href="GUID-E0D0625F-C100-3B83-A385-D3702D5AD434.dita"><apiname>TXmlEngConstString</apiname></xref>  </p> </entry>

    61 <entry><p>Read-only version of <codeph>TXmlEngString</codeph>. </p> </entry>

    62 </row>

    63 </tbody>

    64 </tgroup>

    65 </table> <p>The following table lists the most relevant C structures of the

    66 libxml2 library. </p> <table id="GUID-3AE5C214-E832-5331-9243-534265A5DF9F">

    67 <tgroup cols="2"><colspec colname="col0"/><colspec colname="col1"/>

    68 <thead>

    69 <row>

    70 <entry>API</entry>

    71 <entry>Description</entry>

    72 </row>

    73 </thead>

    74 <tbody>

    75 <row>

    76 <entry><p> <xref href="GUID-5257133A-35CC-3D8D-B56C-E865B45A95D2.dita"><apiname>_xmlDoc</apiname></xref>  </p> </entry>

    77 <entry><p>Document. Provides access to the tree of nodes. </p> </entry>

    78 </row>

    79 <row>

    80 <entry><p> <xref href="GUID-870927E4-4D27-3A49-9672-8C336D8817C3.dita"><apiname>_xmlNode</apiname></xref>  </p> </entry>

    81 <entry><p>Node. Provides access to its children and chain of attributes. </p> </entry>

    82 </row>

    83 <row>

    84 <entry><p> <xref href="GUID-204C12B5-8D50-3BBB-8CFC-20036F3AB787.dita"><apiname>_xmlAttribute</apiname></xref>  </p> </entry>

    85 <entry><p>Attribute. </p> </entry>

    86 </row>

    87 <row>

    88 <entry><p> <xref href="GUID-354C802A-33D5-3E3B-9FAE-C0CD8CE6329C.dita"><apiname>_xmlElement</apiname></xref>  </p> </entry>

    89 <entry><p>Element. </p> </entry>

    90 </row>

    91 <row>

    92 <entry><p> <xref href="GUID-3A2A7AE7-C1FF-3534-9319-400D3B57EC85.dita#GUID-3A2A7AE7-C1FF-3534-9319-400D3B57EC85/GUID-59610388-E6CA-3A12-8403-63D12A2D741B"><apiname>xmlAttributeType::_xmlElementContent</apiname></xref>  </p> </entry>

    93 <entry><p>Container for the contents of an element. </p> </entry>

    94 </row>

    95 <row>

    96 <entry><p> <xref href="GUID-5CF7019B-3D9B-369E-B81C-72D2D2DD1375.dita"><apiname>_xmlSchema</apiname></xref> and <xref href="GUID-2AA3571C-0A78-3C42-8FA2-219E642C2218.dita"><apiname>_xmlDtd</apiname></xref>  </p> </entry>

    97 <entry><p>Validation trees. These structures have no C++ wrappers. </p> </entry>

    98 </row>

    99 <row>

   100 <entry><p> <xref href="GUID-50CFFAE0-5B6D-342D-B372-642055EF7367.dita"><apiname>_xmlXPathParserContext</apiname></xref>  </p> </entry>

   101 <entry><p>XPath evaluation context. </p> </entry>

   102 </row>

   103 </tbody>

   104 </tgroup>

   105 </table> </section>

   106 <section id="GUID-C302F9A6-7E2C-4CC3-991D-F653C4877C56"><title>Typical uses</title> <p>When porting existing software, use

   107 the C functions of the standard libxml2 library and refer to the <xref href="http://xmlsoft.org/html/index.html" scope="external">libxml2 Reference Manual</xref> for more information. </p> <p>To

   108 take advantage of the standard types and exception handling provided by the

   109 Symbian Platform, use the C++ APIs. </p> </section>

   110 </conbody><related-links>

   111 <link href="GUID-77ECD89F-84BB-55F1-9876-382E043F0C0D.dita"><linktext>XML DOM Engine

   112 error handling</linktext></link>

   113 </related-links></concept>