NAME

Weather::NOAA::Alert - Polling and parsing of NOAA CAP 1.1 Alerts

VERSION

Version 0.90

SYNOPSIS

    my $alert = Weather::NOAA::Alert->new(['TXZ104', 'TXC082', 'TXZ097']);
    my $events = $alert->get_events();
    my ($errorCount, $eventCount, $addCount, $deleteCount) = $alert->poll_events();

DESCRIPTION

Weather::NOAA::Alert will retrieve and parse the NOAA National Weather Service ATOM and CAP 1.1 feeds for the specified forecast zones. It is designed to cache previously polled CAP items. The overall process is to get the requested ATOM feed, get any CAP entries that are not in the cache, and store the alerts.

You can find the zone list and more information about NOAA watches, warnings, and advisories at the following sites:

Zone List: http://alerts.weather.gov/
Zone Maps: http://www.weather.gov/mirs/public/prods/maps/pfzones_list.htm

EXAMPLE

    use Weather::NOAA::Alert;
    use Data::Dumper;
 
    my $SLEEP_SECS = 60;   #Poll every 1 minute
 
    #my $alert = Weather::NOAA::Alert->new(['US']);
    my $alert = Weather::NOAA::Alert->new(['TXC085', 'TXZ097']);
    $alert->printLog(1);
    $alert->errorLog(1);

    my $events = $alert->get_events();
 
    while (1) {
         my ($errorCount, $eventCount, $addCount, $deleteCount) 
                 = $alert->poll_events();
       
         print Dumper( $events) . "\n";
       
         print "Tracking $eventCount " . ($eventCount ==1 ? "event" : "events");
         print "   $addCount added, $deleteCount deleted";
         print ", $errorCount " . ($errorCount ==1 ? "error" : "errors");
         print "\n";
         
         print "Sleeping $SLEEP_SECS seconds\n-----------------\n\n";
         sleep($SLEEP_SECS);
     }

METHODS

new - Create a new Weather::NOAA::Alert object

    $alert = Weather::NOAA:Alert->new(@zones);
    $alert = Weather::NOAA:Alert->new();

An array reference may be provided with the list of NOAA forecast zones that should be polled. If the list is not supplied then you must call $object->zones(@zones) to set the zone list prior to calling $object->poll_events().

zones - Set the monitored zone list

    $object->zones([zone1, zone2, ...]);
    @zones = $object->zones();

Setting the zone list will overwrite the existing list with the supplied list. If called with no arguments, returns a reference to the current zone array. To return data for all zones use "US".

get_events - get a reference to the alert object events hash

    %events = $object->get_events();

This is the primary output of the Weather::NOAA::Alert module. The data structure is the result of parsing the NOAA CAP 1.1 objects retrieved for the specified zones. The events hash is indexed first by zone, then by the CAP ID.

Remembers past events in a data structure hash consisting of: {zone}->{CAP id}->{'delete'} ->{'actionTime'} ->{'event'} ->{'certainty'} ->{'senderName'} ->{'urgency'} ->{'instruction'} ->{'description'} ->{'category'} ->{'severity'} ->{'effective'} ->{'headline'} ->{'expires'}

Note that the hash keys are dynamically created from the <info> section of the event. If NOAA adds, renames, or removes an XML parameter it will also change in the structure. In addition, nothing is currently parsed from the event header. There are XML parameters in the header that might be interesting to collect but I didn't have a use for any of that data. Future module revisions might include more of the NOAA data.

SETTINGS