A scrape tool I wrote downloads XHTML documents and parses them using XML::LibXML. As it turns out, it is hammering www.w3.org, fetching http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd (the XHTML DTD) and the three DTD it includes for every document I parse.

Can libxml2 be told to cache this? Or better yet, cache the parsed result? Is this what ext_ent_handler catches? Does someone already have a ext_ent_handler written? It seems silly that I have to do any of this.

See also: W3C Systems Team Blog: W3C's Excessive DTD Traffic.

Update: Well, the following answers my third question affirmatively: 

use strict;
use warnings;

use XML::LibXML qw( );

my $xhtml = <<'__EOI__';
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Test</title>
</head>
<body>Test</body>
</html>
__EOI__

my $parser = XML::LibXML->new(
    ext_ent_handler => sub {
        use Data::Dumper;
        local $Data::Dumper::Useqq = 1;
        print(Dumper(\@_));
        return "";
    },
);

$parser->parse_string($xhtml);

[download]
$VAR1 = [
          "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd",
          "-//W3C//DTD XHTML 1.0 Strict//EN"
        ];

[download]

In reply to Caching Entities with XML::LibXML by ikegami

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.