From: Bob Showalter <bob_showalter@...>
Date: 2006-01-26T02:23:14+09:00
Subject: Re: DRb and ActiveRecord

Ezra Zygmuntowicz wrote:
> Friends-

Advance warning: I am not a drb or ActiveRecord expert. I'm not much of 
an expert on anything, come to think of it :-)

> 
>     I am trying to make a drb server publish an ActiveRecord model so 
> it  can be used by remote clients. 
> ...
> class RemoteRecord < ActiveRecord::Base

You need to make this class undumped:

      include DRb::DRbUndumped

> end
> 
> DRb.start_service("druby://:3500", RemoteRecord)
> puts DRb.uri
> DRb.thread.join
> --------------------------------------
> And my irb session trying to access the remote model.
> ...
> irb(main):006:0> test = DRbObject.new(nil, 'druby://ezra.local:3500')
> => #<DRb::DRbObject:0x1379990 @ref=nil, @uri="druby://ezra.local:3500">
> 
> irb(main):009:0> test.create(:title => 'Foo', :desc => 'Bar')
> => #<DRb::DRbUnknown:0x13727f8 @buf="\004\010o:\021RemoteRecord\010: 
> \020@new_recordF:\f@errorso:\031ActiveRecord::Errors\a;\a{\000: 
> \n@base@\000:\020@attributes{\010\"\ntitle\"\010Foo\"\aidi\010\"\tdesc 
> \"\010Bar", @name="RemoteRecord">

DRbUnknown is your clue here. See:

http://www.ruby-doc.org/stdlib/libdoc/drb/rdoc/classes/DRb/DRbUnknown.html

> ...
> irb(main):013:0> a.title
> NoMethodError: undefined method `title' for #<DRb::DRbUnknown:0x136dce4>
>         from (irb):13

Since "a" is a DRbUnknown object, it doesn't have a title method; hence 
the exception. You need drb to send over a proxy for the object so you 
can send methods back to it. That's what DRb::DRbUndumped does. After 
you make that change, "a" will be a DRb::DRbObject, and the method calls 
will be sent back to the server.

Or something like that...