require 'nokogiri'

class Parser < Nokogiri::XML::SAX::Document
  def start_element(name, attrs = [])
    puts name
  end
  def characters(string)
    string.strip!
    puts string
  end
  def end_element(name)
    puts name
  end
end

Nokogiri::XML::SAX::Parser.new(Parser.new).parse(File.open('sax_example3.xml'))

<?xml version="1.0" encoding="UTF-8"?>
<root>
    <ISA type="array">
        <ISA>
            <I02>
                <name>Information1</name>
                <value>
                    <raw>00</raw>
                    <description></description>
                </value>
            </I02>
            <I02>
                <name>Information2</name>
                <value>
                    <raw></raw>
                    <description nil="true"/>
                </value>
            </I02>
        </ISA>
    </ISA>
</root>