Your package doesn't match the filename, see Simple Module Tutorial , the filename should match the package name.

Instead of comments write documentation :) Tutorials: POD in 5 minutes and maybe

See Modern Perl and Class::Inspector AND Howto create a Moose baseclass/superclass/contract? Moose equivalent of Module::Pluggable? Favorite way to create base/super class?

You might start with

module-starter --author="David Luu" --email=man...mail.com --license=LGPL --module=RobotRemoteServer,RobotRemoteServer::Frontier,RobotRemoteServer,RobotRemoteServer::RPCXMLServer

Added to MANIFEST: Changes
Added to MANIFEST: ignore.txt
Added to MANIFEST: lib/RobotRemoteServer.pm
Added to MANIFEST: lib/RobotRemoteServer/Frontier.pm
Added to MANIFEST: lib/RobotRemoteServer/RPCXMLServer.pm
Added to MANIFEST: Makefile.PL
Added to MANIFEST: MANIFEST
Added to MANIFEST: README
Added to MANIFEST: t/00-load.t
Added to MANIFEST: t/boilerplate.t
Added to MANIFEST: t/manifest.t
Added to MANIFEST: t/pod-coverage.t
Added to MANIFEST: t/pod.t
Created starter directories and files

Then maybe write something like

package RobotRemoteServer;
use Class::Inspector;

sub get_keyword_names {
    my ($self) = @_;
    my $class = $self->lib;
    my @methods = Class::Inspector->methods( $class, 'public' );
    return \@methods;
}

sub run_keyword {
   my $self = shift;
   my ($stdout, $stderr) = capture { ... };
}
sub start_server {
    my $self = shift;
    $self->backend->start_server;
}
[download]

package RobotRemoteServer::Frontier;
sub _shut_down_request {
RobotRemoteServer::Frontier
sub start_server {
  my ($self) = @_;
  my $svr = Frontier::Daemon->new(
    methods => {
      get_keyword_names => sub { $self->get_keyword_names(@_) },
      run_keyword => sub { $self->run_keyword($_[0], eval{@{$_[1]}}) }
+,
      stop_remote_server => sub {
          $srv->_shutdown('yes please');
          $self->schedule_shutdown;
          return;
      },
    ....
}

sub schedule_shutdown {
    my $self = shift;
    my $url = $self->url;
    if( eval { require threads; } ){
        threads::async {
           sleep 5;
           require Frontier::Client;
           Frontier::Client->new( 'url' => $url )->call('stop_remote_s
+erver');
        };
    } elsif( eval { require Proc::Background; } ){
        Proc::Background->new(
            $^X,
            '-e', q{
use Frontier::Client;
sleep 5;
my $url = shift @ARGV;
Frontier::Client->new( 'url' => $url )->call('stop_remote_server');
exit;       },
            $url,
        );
    }
}
sub Frontier::Daemon::_shutdown {
    my( $self, $true ) = @_;
    ${*$self}{'_Frontier::Daemon::_shutdown'} = !!$true if $true; 
    return ${*$self}{'_Frontier::Daemon::_shutdown'} ;
}

sub Frontier::Daemon::accept { ## monkeypatch
    package Frontier::Daemon;
    my $self = shift;
    if( $self->_shutdown ){
        close $self;
        return;
    } else {
        return $self->SUPER::accept;
    }
}
[download]

To handle shutdown in similar way as https://robotframework.googlecode.com/hg/tools/remoteserver/robotremoteserver.py you could monkeypatch shutdown, but writing your own frontier deaemon ( Frontier::Daemon::Forking ) is probably the correct way to do it

backend is the new argument, RobotRemoteServer::Frontier by default

use RobotRemoteServer;
#my $rob = RobotRemoteServer->new (qw' host localhost port 666  ');
my $rob = RobotRemoteServer->new (qw'
  host    localhost 
  port    666 
  backend Frontier
  lib     ExampleLibrary
');
$rob->start_server;
[download]

Maybe it makes more sense for backends to be named as RobotRemoteServer::Backend::Frontier ...

But that is a start, pod beats comments, seperate backends into seperate modules, use existing modules for introspection , has-a not isa-a ...

Future direction:
maybe Moo/Moose or Badger for accessors/mutators...
Maybe POE server ( ex Hopkins::Plugin::RPC ), ex?Catalyst::Plugin::Server::XMLRPC, Plack for ideas
maybe cooperation with Daemon::Generic, AnyEvent::XMLRPC, ...

If I were more knowledgeable, I might make better suggestions ;)