wwwatchdog.pm
    The library is intended to facilitate web site availability checks. It
    processes a list of base URLs and URIs to visit, reports problems
    detected (broken or slow pages).

    It's supposed to be used in inversion of control environment, i.e.
    there's a controller script defining the lists to process and the
    notificaton routines, it then calls wwwatchdog::process subroutine to
    perform actions (URL checks and customer notifications) based on those
    lists. A sample of controller script can be seen in poll-sample.pl,
    test-suite.pl can be run to check wwwatchdog.pm proper functioning.

    The controller script is meant to be put in crontab with short interval
    (like run every 5 minutes).

   init_ua()
    The subroutine does additional initialization to a LWP::UserAgent object
    (it sets some default headers and creates a cookie jar if requested).
    It's used in a few places in the "process()" function .

    Arguments:

    $ua - LWP::UserAgent or derivative object to perform the initialization
    on.
    $session_support (boolean) - whether to initialize cookie jar or not.

   process()
    The main function that performs actions as prescribed by controller
    script.

    Arguments:

    $targets (hashref) - the list of URLs and URIs to process. It's
    stuctured as a nested tree and is of complex stucture. See
    poll-sample.pl for ideas on how to make it up for your needs.
    $default_notifier (sub ref) - a function taking two params (Subject and
    Message) and reporting them to the script customer (by sending an e-mail
    or other means). It's supposed to be defined in the controller script.
    It can be overridden on per-URL basis in $targets param.
    $custom_ua (Test::LWP::UserAgent object of sub ref, optional) - the
    script allows to override the UserAgent object for automated testing
    purposes.

  author
    Victor Ichalov <[email protected]>, 2015.