Url Observer: monitor changes of web pages according to user-defined XPath rules. Written in Perl, use YAML config format. Dead simple.

Require (cpan install):

• LWP::UserAgent
• HTML::TreeBuilder::XPath
• XML::XPath
• XML::XPath::XMLParser
• YAML::Syck
• Digest::MD5
• Text::Diff

Use:

perl urlobs.pl example.yaml

YAML format is a list of entry where:

• url: is the url
• xpath: XPath rule selecting monitored nodes (text extracted)
• title: used for humans [optional]
• interval: is the minimum fetching interval (seconds) [optional]
• type: whether it is html or xml [missing means html]
• no_order: whether we do a sorting (effectively ignoring the output ordering)
• keep_old: whether we should ignore deletions by keeping old entries (useful for youtube RSS, they blink). This option forces no_order by default.
• user_agent: Specify the browser signature, useful to circumvent certain useless site protections [optional].
• cookie: raw data sent directly as the Cookie header [optional]

The file is modified by the program as a database. Look at example.yml for an example.