Re: A proposal for a General Clustering Framework

[Peter Badovinatz <tabmowzo@yahoo.com>]

--- David Brower <David.Brower@oracle.com> wrote:
> IMO, IBM and Compaq both Got It Right when they
> put an generalized pub/sub event system in the middle
> of their cluster frameworks.   I've been pointing this
> out for a while, but it doesn't seem to have gotten any
> traction-- neither Tweedie's old proposal or Robertson's
> here have one AFAICT.

IBM's clustering has multiple possible subscription points.  One is tightly
synchronized, fully ordered, set semantics, etc.  This is used to drive
failover and such.  This is either contained within the cluster manager and not
a general API (HACMP) or exposed via the Group Services API.

The other seems more what you're referring to, the Event Management API.  This
is not really in the middle, more on the top, as it doesn't provide the
ordering guarantees and such.  But, it does provide a very general mechanism
for publishing and subscribing to almost any kind of event (with some work on
the producer side, depending on what you want to monitor.)  This is intended as
a very extensible monitoring engine, not per se a recovery driver.

> 
> FWIW, xml-rpc is a perfectly fine mechanism for such
> an event system, once you get the subscription mechanism
> in place.  You probably also want more authentication and
> authorization than is used on things that assume private
> networks for cluster traffic.

I, personally, am very uncomfortable with RPC except for local (intra-node)
communications.  I see it could be used as part of the event management type
notification, but, as I'm familiar with it, the events are really just "here
they are" messages, without the kind of execution implied for rpc.

> 
> -dB
> 
> -- 
> Butterflies tell me to say:
> "The statements and opinions expressed here are my own and do not necessarily
> 
>   represent those of Oracle Corporation."

Peter


=====
These have been the opinions of:
Peter R. Badovinatz -- (503)578-5530 (TL 775)
wombat@us.ibm.com/tabmowzo@yahoo.com
and in no way should be construed as official opinion of 
IBM, Corp.

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Linux-cluster: generic cluster infrastructure for Linux
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