use Carp qw(croak);
sub call_service {
   my $svc  = shift;
   my $cmd  = shift;
   my @args = @_;

   my $name = "$svc\::$cmd";
   my $handler = *{$name}{CODE};
   croak "Couldn't find a handler for $name"
     unless $handler;

   # maybe log the invocation to your logfile?

   return $handler->(@args);
}

##</code><code>##

my $handler = \*{$name}{CODE};