From: Brian Candler <B.Candler@...>
Date: 2003-05-30T17:47:52+09:00
Subject: Re: Object Prevaylence vs. OODBMS or Madeleine vs. DyBase

On Fri, May 30, 2003 at 04:56:08PM +0900, Anders Bengtsson wrote:
>  --- Wai-Sun Chia <waisun.chia@hp.com> wrote:
> > Questions:
> > - can Madeleine support multiuser concurrent access? i.e. multiple 
> > instance of the client app can be run simultaneously
> 
> Hi Wai-Sun,
> 
> Madeleine itself doesn't have the concept of multiuser access or remote
> clients, but if you for instance run one Madeleine "server" with a DRb
> (Distributed Ruby) interface, then many DRb clients can work with it.

Beware: multiple DRb clients talking to the same remote object will make
*multiple concurrent method calls* - each incoming request is handled as a
separate thread on the same object at the server side.

Therefore DRb doesn't solve any concurrency issues you may have.

With Madeleine, I believe that serialising access to the database is your
own responsibility - e.g. while reading a group of objects, you want to be
sure that nothing is changing under your feet. But it's so fast that having
a global mutex for database access isn't too big a penalty in many cases.

Regards,

Brian.