From: ptkwt@...1.aracnet.com (Phil Tomson)
Date: 2001-11-26T08:25:15+09:00
Subject: [ruby-talk:26474] DRbUndumped question


I'm using dRuby and I have a Client object which runs on a remote machine 
and is bound by dRuby to a port on that machine.  I want to pass a Task 
object to the Client object on the remote machine and have the Task object 
'run' itself there.

here's part of the Client.rb file:
require 'drb'
class Client

   def initialize
   ...
   end

   def run(taskObj, *args)
      taskObj.run(args) #an object that must respond to 'run'   
   end
end

if $0 == __FILE__
   clientObj = Client.new
   DRb.start_service('druby://0.0.0.0:9000',clientObj)
   DRb.thread.join
end
#end of Client.rb

Here's the Task.rb file which defines a Task class and then attempts to 
send a Task object to Client running on 'remote':

require 'drb'
class Task
   include DRb::DRbUndumped
   def initialize
   end

   def run(*args)
      puts "Task::Run - running #{args}"
   end
end

if $0 == __FILE__
   DRb.start_service()
   client = DRbObject.new(nil,'druby://remote:9000')
   puts client.run(Task.new, "ftp","xyz","abc")
end
#end of Task.rb

Now, if I'm running Client.rb on the remote machine (called 'remote') and 
Task.rb on the local machine, I would have expected to see the message:

Task::Run - running ftpxyzabc

on the STDOUT of the remote machine, instead I see it on the local machine 
- not what I want, I want to have the Task object run on the remote 
machine.

If I comment out the 'include DRb::Undumped' line in Task.rb 
and add 'require Task.rb' to the top of Client.rb (and make sure that 
Task.rb is available on the remote machine - which is, of course the 
drawback of this alternative) it works as I would expect 
(and want) - the message is printed on the remote machine.

So, my question is, what exactly does including DRbUndumped do?  (I 
thought it was to mixin to your own classes so that they could be passed 
by reference to the remote DRbObject, but now I think I misunderstand 
how to use it).

Phil