HTML::Encapsulate - rewrites an HTML page as a self-contained set of files
This document describes HTML::Encapsulate version 0.1
use HTML::Encapsulate qw(download);
# This will download the page at the URL given in the first
# argument into a folder named in the second, here called
# C<bar.html>. The folder will contain all the images and other
# components required to view the page. The page itself will be
# saved as C<index.html>
download "http://foo.com/bar" => "bar.html";
# It also has an OO interface, allows various defaults to be
# adjusted via the %options hash.
my $he = HTML::Encapsulate->new(%options);
$he->download("http://foo.com/bar" => "bar.html");
# HTTP::Requests can also be passed. This enables the result of
# form posts to be captured.
my $request = HTTP::Request->new(GET => 'http://somewhere.com/something.html');
my $download_dir = 'some/directory/path';
The main motivation for this module is for archiving and printing web pages: these typically come in various separate pieces and aren't simple to download as one chunk.
However, it is possible to preserve the content of a web page, but to rewrite the links to the embedded contend like images, stylesheets, etc. so that the downloaded version can be viewed entirely offline.
Once web pages have been downloaded in an "encapsulated" form, they can then be archived, and/or converted into other formats.
The wget command line utility has an option for downloading web pages with their images and stylesheets, rewriting the links to point to the downloaded copies, like this:
wget -kp http://foo.com/bar
This command isn't always convenient, nor available, so it's a fairly non-portable option. This module aims to perform the same function in a portable, pure-perl fashion.
See the documentation for the ->download method for more details.
download($url_or_request, $download_dir, $user_agent)
Essentially constructs a default instance and delegates to its ->download method. See the appropriate documentation for that method. Note that, once created, this instance will be re-used by future calls to download.
Optionally, a LWP::UserAgent instance $user_agent may be supplied for use, e.g. if the download needs to be performed as part of an ongoing session, or needs to have specific properties or behaviour.
If no $user_agent is supplied, a new LWP::UserAgent instance will be created by the default instance used. See the ->new method for details.
$obj = $class->new(%options)
Constructs a new instance with tweaked properties.
Only one option is currently available:
Supplies a LWP::UserAgent instance to use instead of the default. If not supplied, a default new instance will be constructed like this:
$ua = LWP::UserAgent->new(
requests_redirectable => [qw(GET POST HEAD)]
This means that redirects will be followed for GET, HEAD, and (unlike a default instance), POST.
One reason for using an externally supplied user agent might be to download within the context of a session it has created.
This downloads the page obtained by the HTTP::Request $request (which could be a post, or any other request returning HTML) in the directory $download_dir, plus all images and other dependencies needed to render it.
The main HTML document will be saved in $download_dir as 'index.html'. Other dependencies will be saved with filenames composed of an index number (1 for the first item saved, 2 for the second, etc.), plus an extension (taken from the source URL).
By design, this function will dowload but not attempt to process non-html content (i.e. if the 'content-type' header does not end in html). Note also that I've been lazy, so it will still save the content with as index.html as for a HTML page.
The content of the HTML is re-written so that links to dependencies refer to the downloaded files. External dependencies (anything not downloaded) are left as-is.
The following dependencies are handled:
<img href="..."> linked images
<style href="..."> stylesheet links
CSS @import url(...) linked stylesheets
<script src="..."> linked scripts.
<input src="..."> linked images.
CSS url() links.
The following constructs are not handled, but ought to be:
Frames and iframe tags.
These are not handled, and may or may not get implemented:
inline data:// urls
Dependencies are intentionally kept fairly minimal, but do exist. The main non-core ones are HTML::Tidy, HTML::Entities and HTML::TreeBuilder::XPath. See the META.yaml included the distribution for full details.
The internals are a bit of an ugly hack. If I could find something off the shelf which does the job equivalently, I'd have used that. Since I couldn't find anything suitable I whipped this up in a jiffy, and then warped it to support as much as I could.
See the description of ->download for details of what is and isn't implemented.
Please report any bugs or feature requests to bug-HTML-Encapsulate@rt.cpan.org, or through the web interface at http://rt.cpan.org.
Nick Woolley <email@example.com>
Copyright (c) 2009, Nick Woolley <firstname.lastname@example.org>. All rights reserved.
This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlartistic.
BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
To install HTML::Encapsulate, copy and paste the appropriate command in to your terminal.
perl -MCPAN -e shell
For more information on module installation, please visit the detailed CPAN module installation guide.