#!/usr/bin/perl
use strict;
use warnings;

use GRID::Cluster;
use Data::Dumper;

my @host_names = split(/:/, $ENV{GRID_REMOTE_MACHINES});

my ($debug, $max_num_np);
for (@host_names) {
  $debug->{$_} = 0;
  $max_num_np->{$_} = 1;
}

my $cluster = GRID::Cluster->new(host_names => \@host_names,
                                 debug      => $debug,
                                 max_num_np => $max_num_np,
                             );

my $np = $cluster->get_max_np();
my @commands = map { "bc" } 0..$np-1;
my $handles_info = $cluster->open2(@commands);

my @write_handles = @{$handles_info->get_wproc()};
for (my $i = 0; $i < $np; $i++) {
  my $b = syswrite (
            $write_handles[$i],
            "10 + ($i + 1) * 10\n quit\n"
          );
}

my $result = $cluster->close2($handles_info);
print Dumper($result);

__END__

=head1 NAME

bc.pl -- A simple example of a remote command execution
using methods open2 and close2 of a GRID::Cluster object

=head1 SYNOPSIS

  ./bc.pl

=head1 DESCRIPTION

This example uses methods open2 and close2 of a GRID::Cluster object
to create bidirectional pipes for communications among different
processes. The example needs the definition of the the environment
variable GRID_REMOTE_MACHINES. For example, from a bash shell a
user can write:

  export GRID_REMOTE_MACHINES=host1:host2:host3

to set that environment variable.