= LibXML Ruby

== Overview

The libxml gem provides Ruby language bindings for GNOME's Libxml2
XML toolkit. It is free software, released under the MIT License.

libxml-ruby provides several advantages over REXML:

* Speed - libxml is many times faster than REXML
* Features - libxml provides a number of additional features over REXML, including XML Schema Validation, RelaxNg validation, xslt (see libxslt-ruby)
* Conformance - libxml passes all 1800+ tests from the OASIS XML Tests Suite 


== Requirements

libxml-ruby requires Ruby 1.8.4 or higher.  It is dependent on 
the following libraries to function properly:

* libm      (math routines: very standard)
* libz      (zlib)
* libiconv
* libxml2

If you are running Linux or Unix you'll need a C compiler so the extension
can be compiled when it is installed.  If you are running Windows, then install the Windows specific RubyGem which
includes an already built extension.


== INSTALLATION

The easiest way to install libxml-ruby is via Ruby Gems.  To install:

<tt>gem install libxml-ruby</tt>

If you are running Windows, make sure to install the Win32 RubyGem which 
includes an already built binary file.  The binary is built against
libxml2 version 2.6.32 and iconv version 1.12.  Both of these are also 
included as pre-built binaries, and should be put either in the 
libxml/lib directory or on the Windows path.

The Windows binaries are biult with MingW.  The gem also includes 
a Microsoft VC++ 2005 solution.  If you wish to run a debug version
of libxml-ruby on Windows, then it is highly recommended
you use VC++.


== Functionality
libxml is a highly conformant XML parser, passing all 1800+ tests 
from the OASIS XML Tests Suite.  In addition, it includes rich
functionality such as: 

* SAX
* DOM
* XMLReader
* XPath
* XPointer
* XML Schema
* DTDs 
* XSLT (split into the libxslt-ruby bindings) 

libxml-ruby provides impressive coverage of libxml's functionality 
through an easy-to-use C api.  

== Performance
In addition to being feature rich and conformation, the main reason
people use libxml-ruby is for performance.  Here are the results 
of a couple simple benchmarks recently blogged about on the
Web (you can find them in the benchmark directory of the 
libxml distribution).

From http://depixelate.com/2008/4/23/ruby-xml-parsing-benchmarks

               user     system      total        real
 libxml    0.032000   0.000000   0.032000 (  0.031000)
 Hpricot   0.640000   0.031000   0.671000 (  0.890000)
 REXML     1.813000   0.047000   1.860000 (  2.031000)

From https://svn.concord.org/svn/projects/trunk/common/ruby/xml_benchmarks/

               user     system      total        real
 libxml    0.641000   0.031000   0.672000 (  0.672000)
 hpricot   5.359000   0.062000   5.421000 (  5.516000)
 rexml    22.859000   0.047000  22.906000 ( 23.203000) 

== USAGE

For in-depth information about using libxml-ruby please refer
to its online Rdoc documentation.  Some simple examples
are shown below.

=== READING

There are several ways to read xml documents.

  require 'xml'
  doc = XML::Document.file('output.xml')
  root = doc.root
  
  puts "Root element name: #{root.name}"
  
  elem3 = root.find('elem3').to_a.first
  puts "Elem3: #{elem3['attr']}"
  
  doc.find('//root_node/foo/bar').each do |node|
    puts "Node path: #{node.path} \t Contents: #{node.content}"
  end

And your terminal should look like:

  Root element name: root_node
  Elem3: baz
  Node path: /root_node/foo/bar[1]         Contents: 1
  Node path: /root_node/foo/bar[2]         Contents: 2
  Node path: /root_node/foo/bar[3]         Contents: 3
  Node path: /root_node/foo/bar[4]         Contents: 4
  Node path: /root_node/foo/bar[5]         Contents: 5
  Node path: /root_node/foo/bar[6]         Contents: 6
  Node path: /root_node/foo/bar[7]         Contents: 7
  Node path: /root_node/foo/bar[8]         Contents: 8
  Node path: /root_node/foo/bar[9]         Contents: 9
  Node path: /root_node/foo/bar[10]        Contents: 10


=== WRITING

To write a simple document:

  require 'xml'
  
  doc = XML::Document.new()
  doc.root = XML::Node.new('root_node')
  root = doc.root
  
  root << elem1 = XML::Node.new('elem1')
  elem1['attr1'] = 'val1'
  elem1['attr2'] = 'val2'
  
  root << elem2 = XML::Node.new('elem2')
  elem2['attr1'] = 'val1'
  elem2['attr2'] = 'val2'
  
  root << elem3 = XML::Node.new('elem3')
  elem3 << elem4 = XML::Node.new('elem4')
  elem3 << elem5 = XML::Node.new('elem5')
  
  elem5 << elem6 = XML::Node.new('elem6')
  elem6 << 'Content for element 6'
  
  elem3['attr'] = 'baz'
  
  format = true
  doc.save('output.xml', format)

The file output.xml contains:

  <?xml version="1.0"?>
  <root_node>
    <elem1 attr1="val1" attr2="val2"/>
    <elem2 attr1="val1" attr2="val2"/>
    <elem3 attr="baz">
      <elem4/>
      <elem5>
        <elem6>Content for element 6</elem6>
      </elem5>
    </elem3>
    <foo>
      <bar>1</bar>
      <bar>2</bar>
      <bar>3</bar>
      <bar>4</bar>
      <bar>5</bar>
      <bar>6</bar>
      <bar>7</bar>
      <bar>8</bar>
      <bar>9</bar>
      <bar>10</bar>
    </foo>
  </root_node>

== DOCUMENTATION

RDoc comments are included - run 'rake doc' to generate documentation.
You can find the latest documentation at:

* http://libxml.rubyforge.org/rdoc/

== License

See LICENSE for license information.

== MORE INFORMATION

For more information please refer to the documentation.  If you have any
questions, please send email to libxml-devel@rubyforge.org.