An experimental class wrapping druby to make it easy to spawn and control Distributed Ruby servers from within a ruby context. Thus allowing a ruby program to relatively painlessly spawn and control "worker" subprocesses.

dserver.rb

#!/usr/bin/env ruby

require 'tempfile'
require 'drb/drb'


class DServer

  attr_reader :active_server
  attr_reader :service
  attr_accessor :server_object_script
  attr_accessor :server_uri

  @@script_template = ["
    require 'drb/drb'
    require 'drb/acl'


    ", :server_object_script ,"

    # Safety first!
    # disable eval and co
    $SAFE = 1
    # only allow connections from 127.0.0.1
    acl = ACL.new ['deny', 'all', 'allow', '127.0.0.1']

    DRb.start_service('", :server_uri, "', FRONT_OBJECT, :tcp_acl => acl)
    DRb.thread.join
  "]

  def initialize(server_object_script=nil, server_uri=nil)
    @server_object_script = server_object_script
    @server_uri = server_uri
  end

  # start the server by composing the script to a temp file and executing it
  def start
    unless @active_server
      composed_server_script = @@script_template.map do |segment|
        case segment
        when Symbol
          case segment
          when :server_object_script then @server_object_script
          when :server_uri then @server_uri
          end
        else
          segment
        end
      end.join

      script_file = Tempfile.new('drb-server-script')
      script_file.write composed_server_script
      script_file.close

      @active_server = IO.popen "ruby #{script_file.path}"
      # give popen a second to run before continuing
      sleep 1
      script_file.unlink
      @service = DRbObject.new_with_uri @server_uri

      DRb.start_service unless DRb.primary_server
    end
    self
  end

  # Check if this DServer is running
  def active?
    !!@active_server
  end

  # Don't forget to clean up your servers when you're done with them!
  def kill
    if @active_server
      Process.kill 9, @active_server.pid
      @active_server = nil
    end
    self
  end

end

# -- # -- # -- # -- # -- EXAMPLE USAGE -- # -- # -- # -- # -- #

SERVER_URI = "druby://localhost:8788"

SERVICE_SCRIPT = "
  class TimeServer

    def get_current_time
      return Time.now
    end

  end

  FRONT_OBJECT = TimeServer.new
"

timeserver = DServer.new(SERVICE_SCRIPT, SERVER_URI).start

# it works if the time is printed
puts timeserver.service.get_current_time

timeserver.kill