Archive for November, 2009

Using perl to scrape and twitter the ISS sightings.

I have just got one of those electricity monitors and it has a data connection. I am going to write an app to allow it to tweet my power consumption but I’ve got to wait for the data cable so I thought I’d take some time to write a perl script in preparation. I’ve never coded in perl before so its a nice little project.

I decided to code up a script that gets the sightings for the ISS from heaves-above and tweets them. Nothing amazing but it will use a lot of the code I will need to parse the output from the energy monitor and then tweet it.

Below is my code, you’ll need to satisfy the dependencies using CPAN.

UPDATE: Thanks to osfameron, I’ve updated the script to be a little more strict and to use a config file. You need to create a config file in /etc/twitteriss.conf with the following:

twitter_username = someusername
twitter_password = somepassword
location_url = the_url_from_heavens_above



#!/usr/bin/perl

use strict;
use warnings;
use Net::Twitter;
use LWP::Simple;
use HTML::TableContentParser;
use HTML::Strip;
use POSIX qw/strftime/;
use Config::General;

my %config = Config::General->new("/etc/twitteriss.conf")->getall;
die "Could not read config file" unless defined $config{location_url};

my $twitter = Net::Twitter->new(
                                traits => [qw/API::REST/], 
                                username => $config{twitter_username},
                                password => $config{twitter_password}
                                );

my $url = $config{location_url};

my $content = get $url;
die "Couldn’t get $url" unless defined $content;

my $tcp = HTML::TableContentParser->new;
my $tables = $tcp->parse($content);
my $hs = HTML::Strip->new();

foreach my $table (@$tables){
        if (defined($table->{id}) && $table->{id} eq "ctl00_ContentPlaceHolder1_tblPasses"){
                my (undef, undef, @rows) = @{$table->{rows}};
                foreach my $row (@rows){
                        my $sightingdate = $hs->parse($row->{cells}[0]{data});
                        if ($sightingdate eq strftime(‘%d %b’,localtime)){
                                #we have a sighting today!
                                my @data = map $_->{data}, @{$row->{cells}};
                                my ($date, $mag, $starttime, $startel, $startdir, $maxtime, $maxel, $maxdir, $endtime, $endel, $enddir) = @data; 
                                my $tweetline = "ISS today: Mag $mag Starts: $starttime $startdir" . chr(176) . " $startel Max: $maxtime $maxel" . chr(176) . " $maxdir Ends: $endtime $endel" . chr(176) . " $enddir";
                                $twitter->update($tweetline);
                        }
                }
        }
}

Like I said, its my first perl script so I’m sure there are better ways but its a good start and it works! Comments on a postcard to the usual address.

Jay.

Thursday, November 26th, 2009

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