GRID::Machine::Result(3p)

NAME
GRID::Machine::Result - The object describing the result of a GRID::Machine RPC

DESCRIPTION
The class "GRID::Machine::Result" is used by both the local and remote sides of the "GRID::Machine", though most of its methods are called on the remote side.

The result of a RPC is a "GRID::Machine::Result" object. Such object has the following attributes:

•   type

    The "type" of result returned. A string. Fixed by the protocol. Common values are "RETURNED" and "DIED".

•   stdout

    A string containing the contents of "STDOUT" produced during the duration of the RPC

•   stderr

    A string containing the contents of "STDERR" produced during the duration of the RPC

•   results

    A reference to an "ARRAY" containing the results returned by the RPC

•   errcode

    The contents of $? as produced during the RPC

•   errmsg

    The contents of $@ as produced during the RPC

  The Constructor "new"
Syntax:

  GRID::Machine::Result->new(
    stdout => $rstdout,
    errmsg  => $err,
    stderr => $rstderr,
    results => \@results
  )

Builds a new result object.

  The "ok" Method
Returns "TRUE" if the RPC didn't died, i.e. if the "type" attribute is not the string 'DIED'

  The "noerr" Method
Returns "TRUE" if the RPC didn't died and didn't send any messages through stderr. See an example. When running the following program:

  $ cat noerrvsok.pl
  #!/usr/local/bin/perl -w
  use strict;
  use GRID::Machine;

  my $machine = shift || $ENV{GRID_REMOTE_MACHINE};
  my $m = GRID::Machine->new( host => $machine );

  my $r = $m->eval( q{print STDERR "This is the end\n" });

  print "print to STDERR:\n";
  print "<".$r->ok.">\n";
  print "<".$r->noerr.">\n";

  $r = $m->eval( q{warn "This is a warning\n" });

  print "Warn:\n";
  print "<".$r->ok.">\n";
  print "<".$r->noerr.">\n";

we get the following output:

                $ errvsok.pl
                print to STDERR:
                <1>
                <>
                Warn:
                <1>
                <>

  The "result" Method
Returns the first element of the list referenced by the "results" attribute This method is called when a "GRID::Machine::Result" object is evaluated in a Boolean context (i.e. "bool" is overloaded).

  The "Results" Method
Returns the list referenced by the "results" attribute

  The "str" Method. Stringification of a "Result" object
Returns the string made of concatenating "stdout", "stderr" and "errmsg". The Perl operator "q("")" is overloaded using this method. Thus, wherever a "GRID::Machine::Result" object is used on a scalar string context the "str" will be called.

SEE ALSO

•   GRID::Machine

•   GRID::Machine::IOHandle

•   GRID::Machine::Group

•   GRID::Machine::Process

•   GRID::Machine::perlparintro

•   Net::OpenSSH

•   IPC::PerlSSH

•   IPC::PerlSSH::Async

•   Man pages of "ssh", "ssh-key-gen", "ssh_config", "scp", "ssh-agent", "ssh-add", "sshd"

•   <http://www.openssh.com>

AUTHOR
Casiano Rodriguez Leon <casiano@ull.es>

ACKNOWLEDGMENTS
This work has been supported by CEE (FEDER) and the Spanish Ministry of Educacion y Ciencia through Plan Nacional I+D+I number TIN2005-08818-C04-04 (ULL::OPLINK project <http://www.oplink.ull.es/>). Support from Gobierno de Canarias was through GC02210601 (Grupos Consolidados). The University of La Laguna has also supported my work in many ways and for many years.

I wish to thank Paul Evans for his "IPC::PerlSSH" module: it was the source of inspiration for this module. To Alex White, Dmitri Kargapolov, Eric Busto and Erik Welch for their contributions. To the Perl Monks, and the Perl Community for generously sharing their knowledge. Finally, thanks to Juana, Coro and my students at La Laguna.

LICENCE AND COPYRIGHT
Copyright (c) 2007 Casiano Rodriguez-Leon (casiano@ull.es). All rights reserved.

These modules are free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlartistic.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.