Druby two-way communication question

ruby-talk
1

Hello everybody,

I'm stuck with a simple task I want to complete using druby.

I have a server and some client processes. It is easy to make the client
execute code on the server side. But now I want to call back to the client
and execute a function there. But as soon as I pass a client object or
lambda function to the server, it blows up.

Here are my thoughts so far as a minimal example (I really tried to make
it short, so no $SAFE and friends):

== server.rb ==
require 'drb/drb'

class RemoteControl
  include DRb::DRbUndumped

  def initialize(client)
    @client = client
  end

  def callback
    @client.callback
  end
end

# The drb server
class Server
  def initialize(uri)
    @clients = []
    DRb.start_service(uri, self) # Start drb service
  end

  def connect(client)
    remote_control = RemoteControl.new(self, clientcallback) @clients <<
    remote_control
    remote_control
  end
end

TheServer = Server.new('druby://localhost:12345')

DRb.thread.join # Wait for the drb server thread to finish before exiting.
== eof ==

== client.rb ==
require 'drb/drb'

class RemoteControl
  include DRb::DRbUndumped

  def initialize(uri = 'druby://localhost:12345')
    @server = DRbObject.new_with_uri(uri) @remote = @server.connect(self)
  end

  def act
    @remote.callback
  end

  def callback
    puts "Called back"
  end
end

r = RemoteControl.new
r.act
r = nil
== eof ==

It blows up with:
/usr/lib/ruby/1.8/drb/drb.rb:1513:in `current_server':
DRb::DRbServerNotFound (DRb::DRbConnError)
        from /usr/lib/ruby/1.8/drb/drb.rb:1575:in `to_id' from
        /usr/lib/ruby/1.8/drb/drb.rb:981:in `initialize' from
        /usr/lib/ruby/1.8/drb/drb.rb:542:in `new' from
        /usr/lib/ruby/1.8/drb/drb.rb:542:in `dump' from
        /usr/lib/ruby/1.8/drb/drb.rb:581:in `send_request' from
        /usr/lib/ruby/1.8/drb/drb.rb:580:in `each' from
        /usr/lib/ruby/1.8/drb/drb.rb:580:in `send_request' from
        /usr/lib/ruby/1.8/drb/drb.rb:849:in `send_request' from
        /usr/lib/ruby/1.8/drb/drb.rb:1088:in `send_message' from
        /usr/lib/ruby/1.8/drb/drb.rb:1014:in `method_missing' from
        /usr/lib/ruby/1.8/drb/drb.rb:1013:in `open' from
        /usr/lib/ruby/1.8/drb/drb.rb:1013:in `method_missing' from
        ./drb.client.test.rb:11:in `initialize' from
        ./drb.client.test.rb:23:in `new' from ./drb.client.test.rb:23

which is not really helpful to me.

$ ruby -v
ruby 1.8.1 (2004-02-03) [i386-linux]

Thanks a lot for your help.

Brian

···

--
Brian Schröder
http://www.brian-schroeder.de/

2

There are a few slight glitches (probably left from when you cut it down), but the main problem is that you forgot to call DRb.start_service on the client before trying to connect to the server. Once I added that, it worked for me.

HTH,

Nathaniel
Terralien, Inc.

<:((><

···

On Jul 23, 2004, at 08:06, Brian Schroeder wrote:

I'm stuck with a simple task I want to complete using druby.

I have a server and some client processes. It is easy to make the client
execute code on the server side. But now I want to call back to the client
and execute a function there. But as soon as I pass a client object or
lambda function to the server, it blows up.

Here are my thoughts so far as a minimal example (I really tried to make
it short, so no $SAFE and friends):

3

but the main problem is that you forgot to call

DRb.start_service on the client before trying to connect to the server.
Once I added that, it worked for me.

HTH,

That helped indeed. Thanks for taking the time to try out my example and
giving advice.

Regards,

Brian

···

On Sat, 24 Jul 2004 00:56:03 +0900, Nathaniel Talbott wrote:

--
Brian Schröder
http://www.brian-schroeder.de/