NAME

XML::RSS::LibXML - XML::RSS with XML::LibXML (parse-only)

SYNOPSIS

  use XML::RSS::LibXML;
  my $rss = XML::RSS::LibXML->new;
  $rss->parsefile($file);

  print "channel: $rss->{channel}->{title}\n";
  foreach my $item (@{ $rss->{items} }) {
     print "  item: $item->{title} ($item->{link})\n";
  }

  # Add custom modules
  $rss->add_module(uri => $uri, prefix => $prefix);

DESCRIPTION

XML::RSS::LibXML uses XML::LibXML (libxml2) for parsing RSS instead of XML::RSS' XML::Parser (expat), while trying to keep interface compatibility with XML::RSS.

XML::RSS is an extremely handy tool, but it is unfortunately not exactly the most lean or efficient RSS parser, especially in a long-running process. So for a long time I had been using my own version of RSS parser to get the maximum speed and efficiency - this is the re-packaged version of that module, such that it adheres to the XML::RSS interface.

Use this module when you have severe performance requirements in parsing RSS files.

COMPATIBILITY

There seems to be a bit of confusion as to how compatible XML::RSS::LibXML is with XML::RSS: XML::RSS::LibXML is NOT 100% compatible with XML::RSS. For example, XML::RSS::LibXML is not capable of outputting RSS in various formats. It also doesn't do complete parsing of the XML document because of the way we deal with XPath and libxml's DOM (see CAVEATS below)

On top of that, I originally wrote XML::RSS::LibXML as sort of a fast replacement for XML::RAI, which looked cool in terms of abstracting the various modules. And therefore versions prior to 0.02 worked more like XML::RAI rather than XML::RSS. That was a mistake in hind sight, so it has been addressed.

From now on XML::RSS::LibXML will try to match XML::RSS's functionality as much as possible in terms of parsing RSS feeds. Please send in patches and any tests that may be useful!

PARSED STRUCTURE

Once parsed the resulting data structure resembles that of XML::RSS. However, as one addition/improvement, XML::RSS::LibXML uses a technique to allow users to access complex data structures that XML::RSS doesn't support as of this writing.

For example, suppose you have a tag like the following:

  <rss version="2.0">
  ...
    <channel>
      <tag attr1="val1" attr2="val3">foo bar baz</tag>
    </channel>
  </rss>

All of the fields in this construct can be accessed like so:

  $rss->channel->{tag}        # "foo bar baz"
  $rss->channel->{tag}{attr1} # "val1"
  $rss->channel->{tag}{attr2} # "val2"

See XML::RSS::LibXML for details.

METHODS

new

Creates a new instance of XML::RSS::LibXML

parse($string)

Parse a string containing RSS.

parsefile($filename)

Parse an RSS file specified by $filename

as_string()

Return the string representation of the parsed RSS.

add_module(uri => $uri, prefix => $prefix)

Adds a new module. You should do this before parsing the RSS. XML::RSS::LibXML understands a few modules by default:

    rdf     => "http://www.w3.org/1999/02/22-rdf-syntax-ns#",
    dc      => "http://purl.org/dc/elements/1.1/",
    sy      => "http://purl.org/rss/1.0/modules/syndication/",
    admin   => "http://webns.net/mvcb/",
    content => "http://purl.org/rss/1.0/modules/content/",
    cc      => "http://web.resource.org/cc/",
    taxo    => "http://purl.org/rss/1.0/modules/taxonomy/",

So you do not need to add these explicitly.

PERFORMANCE

Here's a simple benchmark using benchmark.pl in this distribution:

  daisuke@localhost XML-RSS-LibXML$ perl -Mlib=lib benchmark.pl index.rdf 
               Rate        rss rss_libxml
  rss        4.43/s         --       -87%
  rss_libxml 35.1/s       694%         --

CAVEATS

No support whatsover for writing RSS. No plans to support it either.

Only first level data under <channel> and <item> tags are examined. So if you have complex data, this module will not pick it up. For most of the cases, this will suffice, though.

TODO

Tests. Currently tests are simply stolen from XML::RSS. It would be nice to have tests that do more extensive testing for correctness

SEE ALSO

XML::RSS, XML::LibXML, XML::LibXML::XPathContext

AUTHORS

Copyright 2005 Daisuke Maki <dmaki@cpan.org>, Tatsuhiko Miyagawa <miyagawa@bulknews.net>. All rights reserved.

Development partially funded by Brazil, Ltd. <http://b.razil.jp>

cpanm XML::RSS::LibXML

perl -MCPAN -e shell
install XML::RSS::LibXML