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List:       linux-ha-dev
Subject:    Re: [Linux-ha-dev] Re: ZDNet on us!
From:       David Brower <dbrower () us ! oracle ! com>
Date:       2000-01-31 19:13:35
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"Stephen C. Tweedie" wrote:
> ...  Sockets are what all existing support
> libraries, such as xdr/rpc, run on top of.  As such, I'd need an
> overwhelming reason not to use that as the primary communications
                                             ^^^^^^^
> architecture for clustering.

Agreed, with emphasis on "primary"; existence of primary need not
exclude other, "secondary" methods.

]
> Umm, sockets *are* the Unix transport-independent messaging layer.  What
> I've already suggested is that we have a name service which lets us open
> or connect to a socket by the cluster node ID, rather than by address.
> That already gives us full protocol independence.  We can run over IP,
> IPX, VIA or whatever if we have that in place, and we don't need to
       ^^^^
> throw away the socket infrastructure to get it.

I';ll get off the boat with Stephen on this point, though.  VIA is one
of the transports I'd strongly consider as a "secondary" interface.  This
is because it's strengths are not well-revealed through a socket interface,
and really cry for other mechanisms to exploit well.   If you're willing
to put up with the socket overhead, the cost of running IP on it is trivial,
so you might as well just make it another IP stack at that point.

 > I also know that even without clustering, there is a tremendous
> > opportunity to provide GPL Message Queuing services in Linux (which
> > will give application programmers a lot of power, and increase Linux
> > integration with other platforms).
> 
> I agree, but I just don't think that we want to build it as a core
> cluster component on which the functioning cluster services will
> depend.  Rather it should be something we can offer to applications
> later.

Messaging is interesting, and good, but there is no architecturally
compelling reason to put it into the core cluster infrastructure.  Using
Occam's Razor, it is wise to limit the scope of the cluster effort as
much as possible; that means leaving messaging fans in search of their
own vehicle (bus, I guess) for community development.

-dB

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