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From James Strachan <james_strac...@yahoo.co.uk>
Subject [clustering] (was Re: Volunteers - Topics AND Clustering)
Date Tue, 12 Aug 2003 18:19:06 GMT

On Tuesday, August 12, 2003, at 06:32  pm, Harman, Jeff wrote:

> I would like to work on Clustering and possibly JMS services that run 
> in a cluster.

Me too :)

>
> To wit:
> The J2EE 1.4 spec does not specifically address clustering but, I 
> believe that it is an essential service to have in order to gain 
> acceptance as a J2EE container.

Agreed.


> We could follow JBoss's lead and use something like JavaGroups to help 
> maintain state or we could layer it on top of other mechanisms like 
> JMS and allow JMS to manage intra-process communications.  Of course 
> this would require that the JMS mechanisms be distributed (unlike 
> JBoss).
>
> IMHO, I believe that JMS should act as a client of the cluster and not 
> the other way around.

Agreed.

The only point of the above to note is that JavaGroups is LGPL and we 
cannot import any LGPL code into any Apache code. Basically *GPL is 
viral so we cannot import directly any *GPL code.

However if we were to create a facade API (maybe with Bela and the 
other JavaGroups folks) that abstracted JavaGroups and made the API BSD 
licenced and JavaGroups implemented it then that would be fine. i.e. 
that LGPL code imported our BSD code and not the other way around.

This API would also allow us to have a JMS implementation as well.

I've had some conversations with Bela about this and he seems OK with 
helping to create this facade API. (There's even been talk of turning 
this facade API into a JSR for Group Communication).

Or another approach is we create the API ourselves as part of Geronimo 
to abstract out what we actually need from a group communication layer; 
then this could be implemented outside of Apache for JavaGroups and 
inside Apache for JMS. (Unfortunately this would mean we could not 
certify with JavaGroups, only with JMS).

An even simpler solution would be to persuade Bela to licence 
JavaGroups as BSD :)

James
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http://radio.weblogs.com/0112098/


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