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[scpubgit/Object-Remote.git] / lib / Object / Remote.pm

package Object::Remote;

use Object::Remote::MiniLoop;
use Object::Remote::Handle;
use Object::Remote::Logging qw( :log );
use Module::Runtime qw(use_module);

our $VERSION = '0.002003'; # 0.2.3

BEGIN { 
  Object::Remote::Logging->init_logging; 
}

sub new::on {
  my ($class, $on, @args) = @_;
  my $conn = __PACKAGE__->connect($on);
  log_trace { sprintf("constructing instance of $class on connection for child pid of %i", $conn->child_pid) };
  return $conn->remote_object(class => $class, args => \@args);
}

sub can::on {
  my ($class, $on, $name) = @_;
  my $conn = __PACKAGE__->connect($on);
  log_trace { "Invoking remote \$class->can('$name')" };
  return $conn->remote_sub(join('::', $class, $name));
}

sub new {
  shift;
  Object::Remote::Handle->new(@_)->proxy;
}

sub connect {
  my ($class, $to) = @_;
  use_module('Object::Remote::Connection')->maybe::start::new_from_spec($to);
}

sub current_loop {
  our $Current_Loop ||= Object::Remote::MiniLoop->new
}

1;

=head1 NAME

Object::Remote - Call methods on objects in other processes or on other hosts

=head1 SYNOPSIS

Creating a connection:

  use Object::Remote;

  my $conn = Object::Remote->connect('myserver'); # invokes ssh

Calling a subroutine:

  my $capture = IPC::System::Simple->can::on($conn, 'capture');

  warn $capture->('uptime');

Using an object:

  my $eval = Eval::WithLexicals->new::on($conn);

  $eval->eval(q{my $x = `uptime`});

  warn $eval->eval(q{$x});

Importantly: 'myserver' only requires perl 5.8+ - no non-core modules need to
be installed on the far side, Object::Remote takes care of it for you!

=head1 DESCRIPTION

Object::Remote allows you to create an object in another process - usually
one running on another machine you can connect to via ssh, although there
are other connection mechanisms available.

The idea here is that in many cases one wants to be able to run a piece of
code on another machine, or perhaps many other machines - but without having
to install anything on the far side.

=head1 COMPONENTS

=head2 Object::Remote

The "main" API, which provides the L</connect> method to create a connection
to a remote process/host, L</new::on> to create an object on a connection,
and L</can::on> to retrieve a subref over a connection.

=head2 Object::Remote::Connection

The object representing a connection, which provides the
L<Object::Remote::Connection/remote_object> and
L<Object::Remote::Connection/remote_sub> methods that are used by
L</new::on> and L</can::on> to return proxies for objects and subroutines
on the far side.

=head2 Object::Remote::Future

Code for dealing with asynchronous operations, which provides the
L<Object::Remote::Future/start::method> syntax for calling a possibly
asynchronous method without blocking, and
L<Object::Remote::Future/await_future> and L<Object::Remote::Future/await_all>
to block until an asynchronous call completes or fails.

=head1 METHODS

=head2 connect

  my $conn = Object::Remote->connect('-'); # fork()ed connection

  my $conn = Object::Remote->connect('myserver'); # connection over ssh

  my $conn = Object::Remote->connect('user@myserver'); # connection over ssh

  my $conn = Object::Remote->connect('root@'); # connection over sudo

=head2 new::on

  my $eval = Eval::WithLexicals->new::on($conn);

  my $eval = Eval::WithLexicals->new::on('myserver'); # implicit connect

  my $obj = Some::Class->new::on($conn, %args); # with constructor arguments

=head2 can::on

  my $hostname = Sys::Hostname->can::on($conn, 'hostname');

  my $hostname = Sys::Hostname->can::on('myserver', 'hostname');

=head1 ENVIRONMENT

=over 4

=item OBJECT_REMOTE_PERL_BIN

When starting a new Perl interpreter the contents of this environment
variable will be used as the path to the executable. If the variable
is not set the path is 'perl'

=item OBJECT_REMOTE_LOG_LEVEL

Setting this environment variable will enable logging and send all log messages
at the specfied level or higher to STDERR. Valid level names are: trace debug
verbose info warn error fatal

=item OBJECT_REMOTE_LOG_FORMAT

The format of the logging output is configurable. By setting this environment variable
the format can be controlled via printf style position variables. See
L<Object::Remote::Logging::Logger>.

=item OBJECT_REMOTE_LOG_FORWARDING

Forward log events from remote connections to the local Perl interpreter. Set to 1 to enable
this feature which is disabled by default. See L<Object::Remote::Logging>.

=item OBJECT_REMOTE_LOG_SELECTIONS

Space seperated list of class names to display logs for if logging output is enabled. Default
value is "Object::Remote::Logging" which selects all logs generated by Object::Remote.
See L<Object::Remote::Logging::Router>.

=back

=head1 SUPPORT

IRC: #web-simple on irc.perl.org

=head1 AUTHOR

mst - Matt S. Trout (cpan:MSTROUT) <mst@shadowcat.co.uk>

=head1 CONTRIBUTORS

phaylon - Robert Sedlacek (cpan:PHAYLON) <r.sedlacek@shadowcat.co.uk>

triddle - Tyler Riddle (cpan:TRIDDLE) <t.riddle@shadowcat.co.uk>

=head1 SPONSORS

Parts of this code were paid for by

  Socialflow L<http://www.socialflow.com>

  Shadowcat Systems L<http://www.shadow.cat>

=head1 COPYRIGHT

Copyright (c) 2012 the Object::Remote L</AUTHOR>, L</CONTRIBUTORS> and
L</SPONSORS> as listed above.

=head1 LICENSE

This library is free software and may be distributed under the same terms
as perl itself.

=cut