From: Jon Smirl Date: 2005-12-17T08:18:54+09:00 Subject: Parsing xhtml with libxml If you get errors complaining of undefined entities like when parsing xhtml it means you need to install the DTD for xhtml 1.0 or 1.1. Example of a doctype for xhtml 1.1: You want to install the DTDs locally following the model in /etc/xml. If you don't libxml will fetch the DTD from www.w3.org each time you parse a document. Needing to install these DTDs was not obvious to me and should be part of the documentation. There a rpm for xhtml 1.0 - "xhtml1-dtds-1.0-7". I couldn't find one for xhtml 1.1 so I downloaded it piecemeal from w3.org. Installing the DTD does not automatically turn on validation. If you want to validate you need to turn it on: XML::Parser::default_validity_checking = TRUE XML::Parser::default_load_external_dtd controls the loading of the 'external subset' (the definition for the character entities like &. It is defaulted to TRUE. XML::Parser::default_load_external_dtd is broken. This fixes it. Index: ruby_xml_parser.c ========================================================== RCS file: /var/cvs/xml-tools/libxml-ruby/ruby_xml_parser.c,v retrieving revision 1.1.1.1 diff -r1.1.1.1 ruby_xml_parser.c 274c274 < if (xmlSubstituteEntitiesDefaultValue) --- > if (xmlLoadExtDtdDefaultValue) 916c916 < ruby_xml_parser_default_load_external_dtd_set, 0); --- > ruby_xml_parser_default_load_external_dtd_get, 0); 918c918 < ruby_xml_parser_default_load_external_dtd_get, 1); --- > ruby_xml_parser_default_load_external_dtd_set, 1); Sam's patches for libxml are also needed: http://www.intertwingly.net/blog/2005/11/05/Patch-for-libxml2s-Ruby-binding