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Re: [Vrs-development] CMM Messages

From: Chris Smith
Subject: Re: [Vrs-development] CMM Messages
Date: Fri, 1 Mar 2002 18:13:50 +0000

Just a few quick points, I'll do more later.....

On Friday 01 March 2002 14:40, Bill Lance wrote:

> Does this upper limit have to be determined at compile
> time or later in configuration?

It's a configuration parameter.  If you've got lots of
memory, then you can allocate more (without incurring
hideous paging!)

> > So an LDS would contact another LDS (I was thinking
> > via
> > the webService access port because that's the public
> > bit)
> > and 'subscribe' to the VRS.  If accepted, it's
> > GWDomain
> > details would be added to Goldwaters runtime config.
> It sounds like there are certainly going to be
> overlaps in the data GW needs and the Cluster Image.
> Can we move those GW tables into the CI?

GW will handle all the communication and message routing
between LDSs.  As such it needs to know about each LDS
(that GW is told about dynamically by the CI manager).
GW takes care of whether LDSs (as they are GWDomains) are
up/down etc.
Knowledge of an GWDomain (LDS) will persist until GW is
rebooted or the CI manager tells GW that it has

So the overlap is just that an LDS needs to know about
all the other LDSs, and so does GW.
GW   sees them as GWDomains,
LDSs see them as other LDSs.

The only way for one LDS to send msgs to another LDS is
via GW:

Here the CIM on LDS A sends a message to CIM on LDS B.
It gets there by dropping into the Goldwater layer where
it gets routed and sent.

         LDS A                           LDS B

    -----------------             -------------------
CIM     msg -->--+                   +-->-- msg     
    -------------|---             ---|---------------
GW               +------>------>-----+
    -----------------             -------------------

- What LDSs comprise the Cluster is a CI issue, and so that
   information is held in the CI.
- Where LDSs are and whether they are available etc is a 
   Goldwater issue, as GW handles all network comms and 

The CI may look at GW's tables to see if an LDS is available
before sending a message.  Even if GW says that it is available,
the message may fail to be sent, and so GW will update its
tables to reflect this and provide feedback to the CI.

So I wouldn't say it's an overlap - more of common data.
This common data cannot reside in an application built on top
of Goldwater because GW knows nothing about the application.

Applications however know everything about Goldwater, and can
thus freely access any data/tables that Goldwater exposes.

Besides, without GW knowing about ip/port and availability
of other GWDomains, then it's not going to be able to do
anything is it???? :o)


Chris Smith
  Technical Architect - netFluid Technology Limited.
  "Internet Technologies, Distributed Systems and Tuxedo Consultancy"
  E: address@hidden  W: http://www.nfluid.co.uk

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