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From Brian McCallister <mccallis...@forthillcompany.com>
Subject Re: Distributed Lock Management
Date Tue, 07 Sep 2004 15:13:20 GMT
I am looking, in the very near future, to do a simple dirty-only cache 
replication system based on ActiveMQ/ActiveCluster as well.

My plans are to simply use topic support and broadcast TextMessage 
impls with table names and pk values of rows that need to be flushed. 
The idea is to crank up local caching and only transmit dirty changes. 
Replicating the whole object is too expensive on a large cluster. Using 
table+pk allows non-OJB apps making changes to participate as well by 
producing/subscribing and understanding the schema.

If you can get on IRC during the day (day meaning daytime and early 
evening in London) James Strachan is usually available and quite 
willing to help on irc.codehaus.org in #activemq

Having ODMG lockmap support in it would be very handy. I would suggest 
starting with activemq's built-in multicast support for local networks 
since the total size of identity+locktype should (really should!) be 
smaller than the broadcast packet size. If you (we) need bigger 
packets, using the jgroups support would probably be the next step. The 
reason for the multicast:// or jgroups:// is exactly that single point 
of failure problem. Both of these impls are fully peer-to-peer in 


On Sep 7, 2004, at 10:35 AM, Charles Anthony wrote:

> Hi All,
> We're looking into making our application clustered. Well, actually, we
> *are* making our application clustered (using multiple server processes
> residing on multiple servers reading requests off a JMS queue). It 
> looks
> really rather cool.
> What we need to do now is cope with distributed ODMG locking. I 
> realise that
> we have the Servlet LockMap which I shall certainly look at, but I 
> have to
> say, I'm a little concerned about having a single point of failure 
> (which is
> what I think would be the case - but please correct me if I'm wrong).
> I am thinking of implementing a distributed LockMap using JMS, 
> possibly on
> top of activecluster.codehause.org - but has anyone got any pointers 
> for me
> for building lock managers/maps ? Other products/papers/discussions 
> that I
> can read up on ? Basically, from the OJB point of view, I think that 
> the
> thing to do is to create implement a new LockMap.
> Cheers,
> Charles.
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