#!/usr/bin/env perl

use strict;
use warnings;

use CGI ();
use JSON ();

my $q     = CGI->new;
my $json  = JSON->new->utf8;
my $input = $json->decode( $q->param('POSTDATA') );

my $a = $input->{a};
my $b = $input->{b};
my $c = $a + $b;

print $q->header("application/json");
print $json->encode({ c => $c });

##</code><code>##

#!/usr/bin/env perl

use strict;
use warnings;

use JSON ();
use LWP::UserAgent ();
use HTTP::Request::Common qw( POST );

my $data = { a => 40, b => 2 };

my $json = JSON->new->utf8;
my $ua   = LWP::UserAgent->new;

my $req = POST(
	"http://buzzword.org.uk/2013/json-addition.cgi",
	Content_Type => 'application/json',
	Content      => $json->encode($data),
);

my $result = $json->decode( $ua->request($req)->decoded_content );
print $result->{c}, "\n";