XML::XUpdate::LibXML(3pm) User Contributed Perl Documentation XML::XUpdate::LibXML(3pm)NAME
XML::XUpdate::LibXML - Simple implementation of XUpdate format
SYNOPSIS
use XML::LibXML; use XML::XUpdate::LibXML;
$parser = XML::LibXML->new(); $dom = $parser->parse_file("mydoc.xml"); $actions = $parser->parse_file("update.xml");
$xupdate = XML::XUpdate::LibXML->new(); $xupdate->process($dom->getDocumentElement(), $actions); print $dom->toString(),"
";
DESCRIPTION
This module implements the XUpdate format described in XUpdate Working Draft from 2000-09-14
(http://www.xmldb.org/xupdate/xupdate-wd.html). The implementation is based on XML::LibXML DOM API.
"new"
my $xupdate = XML::XUpdate::LibXML->new();
Creates a new XUpdate object. You may use this object to update several different DOM trees using several different XUpdate descriptions.
The advantage of it is that an xupdate object remembers values all variables declared in XUpdate documents.
"$xupdate->registerNs($prefix,$uri)"
Tell the XPath engine to resolve given namespace prefix as the given namespace URI. This is particularly useful to bind a default namespace
to a prefix because XPath doesn't honour default namespaces.
"$xupdate->process($document_dom,$xupdate_dom)"
This function takes two DOM trees as its arguments. It works by updating the first tree according to all XUpdate commands included in the
second one. All XUpdate commands must be children of the root element of the second tree and must all belong to XUpdate namespace
"http://www.xmldb.org/xupdate". The namespace URI may be changed with set_namespace method.
"$xupdate->set_namespace($URI)"
You may use this method to change the namespace of XUpdate elements. The default namespace is "http://www.xmldb.org/xupdate".
"$xupdate->namespace()"
Returns XUpdate namespace URI used by XUpdate processor to identify XUpdate commands.
EXPORT
None.
DIFFERENCES BETWEEN 0.2.x and 0.3.x
In 0.3.x different implementation of XUpdate variables is used. Now variables contain the actual objects resulting from an XPath query, and
not their textual content as in versions 0.2.x of XML::XUpdate::LibXML.
Also, value-of instruction results in copies of the actual objects it selects rather than their textual content as in 0.2.x.
I hope the new implementation is more conformant with the (not very clear) XUpdate Working Draft and therefore more compatible with other
XUpdate implementations.
DIFFERENCES BETWEEN 0.3.x and 0.4.x
Commands are applied to all nodes of the select nodeset, not just the first one.
DIFFERENCES BETWEEN 0.4.x and 0.5.x
XML::LibXML::XPathContext is used for variable code providing more flexible and powerfull implementation. New and hopefully correct
implementation of the problematic child attribute of update command has been introduced.
Support for registrering namespace prefix with the XPath engine (allows binding document's default namespace to a prefix).
Several bug fixes.
DIFFERENCES BETWEEN 0.5.x and 0.6.x
xu:if command implementation contributed by Amir Guindehi.
AUTHOR
Petr Pajas, pajas@matfyz.cz
COPYRIGHT
Copyright 2002-2005 Petr Pajas, All rights reserved.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
SEE ALSO
XML::LibXML XML::LibXML::XPathContext
perl v5.10.1 2005-05-13 XML::XUpdate::LibXML(3pm)
Check Out this Related Man Page
XML::LibXML::DOM(3pm) User Contributed Perl Documentation XML::LibXML::DOM(3pm)NAME
XML::LibXML::DOM - XML::LibXML DOM Implementation
DESCRIPTION
XML::LibXML provides an light-wight interface to modify a node of the document tree generated by the XML::LibXML parser. This interface
follows as far as possible the DOM Level 3 specification. Additionally to the specified functions the XML::LibXML supports some functions
that are more handy to use in the perl environment.
One also has to remember, that XML::LibXML is an interface to libxml2 nodes which actually reside on the C-Level of XML::LibXML. This means
each node is a reference to a structure different than a perl hash or array. The only way to access these structure's values is through the
DOM interface provided by XML::LibXML. This also means, that one can't simply inherit an XML::LibXML node and add new member variables as
they were hash keys.
The DOM interface of XML::LibXML does not intend to implement a full DOM interface as it is done by XML::GDOME and used for full featured
application. Moreover, it offers an simple way to build or modify documents that are created by XML::LibXML's parser.
Another target of the XML::LibXML interface is to make the interfaces of libxml2 available to the perl community. This includes also some
workarounds to some features where libxml2 assumes more control over the C-Level that most perl users don't have.
One of the most important parts of the XML::LibXML DOM interface is, that the interfaces try do follow the DOM Level 3 specification
(http://www.w3.org/TR/DOM-Level-3-Core/ <http://www.w3.org/TR/DOM-Level-3-Core/>) rather strictly. This means the interface functions are
named as the DOM specification says and not what widespread Java interfaces claim to be standard. Although there are several functions that
have only a singular interface that conforms to the DOM spec XML::LibXML provides an additional Java style alias interface.
Also there are some function interfaces left over from early stages of XML::LibXML for compatibility reasons. These interfaces are for
compatibility reasons only. They might disappear in one of the future versions of XML::LibXML, so a user is requested to switch over to the
official functions.
Encodings and XML::LibXML's DOM implementation
See the section on Encodings in the XML::LibXML manual page.
Namespaces and XML::LibXML's DOM implementation
XML::LibXML's DOM implementation is limited by the DOM implementation of libxml2 which treats namespaces slightly differently than required
by the DOM Level 2 specification.
According to the DOM Level 2 specification, namespaces of elements and attributes should be persistent, and nodes should be permanently
bound to namespace URIs as they get created; it should be possible to manipulate the special attributes used for declaring XML namespaces
just as other attributes without affecting the namespaces of other nodes. In DOM Level 2, the application is responsible for creating the
special attributes consistently and/or for correct serialization of the document.
This is both inconvenient, causes problems in serialization of DOM to XML, and most importantly, seems almost impossible to implement over
libxml2.
In libxml2, namespace URI and prefix of a node is provided by a pointer to a namespace declaration (appearing as a special xmlns attribute
in the XML document). If the prefix or namespace URI of the declaration changes, the prefix and namespace URI of all nodes that point to it
changes as well. Moreover, in contrast to DOM, a node (element or attribute) can only be bound to a namespace URI if there is some
namespace declaration in the document to point to.
Therefore current DOM implementation in XML::LibXML tries to treat namespace declarations in a compromise between reason, common sense,
limitations of libxml2, and the DOM Level 2 specification.
In XML::LibXML, special attributes declaring XML namespaces are often created automatically, usually when a namespaced node is attached to
a document and no existing declaration of the namespace and prefix is in the scope to be reused. In this respect, XML::LibXML DOM
implementation differs from the DOM Level 2 specification according to which special attributes for declaring the appropriate XML
namespaces should not be added when a node with a namespace prefix and namespace URI is created.
Namespace declarations are also created when XML::LibXML::Document's createElementNS() or createAttributeNS() function are used. If the a
namespace is not declared on the documentElement, the namespace will be locally declared for the newly created node. In case of Attributes
this may look a bit confusing, since these nodes cannot have namespace declarations itself. In this case the namespace is internally
applied to the attribute and later declared on the node the attribute is appended to (if required).
The following example may explain this a bit:
my $doc = XML::LibXML->createDocument;
my $root = $doc->createElementNS( "", "foo" );
$doc->setDocumentElement( $root );
my $attr = $doc->createAttributeNS( "bar", "bar:foo", "test" );
$root->setAttributeNodeNS( $attr );
This piece of code will result in the following document:
<?xml version="1.0"?>
<foo xmlns:bar="bar" bar:foo="test"/>
The namespace is declared on the document element during the setAttributeNodeNS() call.
Namespaces can be also declared explicitly by the use of XML::LibXML::Element's setNamespace() function. Since 1.61, they can also be
manipulated with functions setNamespaceDeclPrefix() and setNamespaceDeclURI() (not available in DOM). Changing an URI or prefix of an
existing namespace declaration affects the namespace URI and prefix of all nodes which point to it (that is the nodes in its scope).
It is also important to repeat the specification: While working with namespaces you should use the namespace aware functions instead of the
simplified versions. For example you should never use setAttribute() but setAttributeNS().
AUTHORS
Matt Sergeant, Christian Glahn, Petr Pajas
VERSION
2.0001
COPYRIGHT
2001-2007, AxKit.com Ltd.
2002-2006, Christian Glahn.
2006-2009, Petr Pajas.
perl v5.14.2 2012-06-20 XML::LibXML::DOM(3pm)