[MUD-Dev] Re: Graphic design, client questions

[J C Lawrence <claw#under,engr.sgi.com>]

On Fri, 18 Dec 1998 10:45:48 -0600 
Sunny Gulati<sunnywiz#radiks,net> wrote:

> Thinus Barnard wrote:

> This raises a deeper philosophical question:

> To mirror the state of one entity to another entity, do you:
>   -- mirror EVERY possible incremental change to the entity? 
>   -- Cover one's rear by occasionally doing a state dump anyway?

The standard approach I've seen used:

  1) While objects are within each other's direct working sets the
exchange updates as state changes occur (this is part of the
standard notify message semantics).

  2) Periodically exchange checksum's of their current states and
use that to ensure correctness (update only as needed).  This
prevents slippage (and should be logged as a form of error
detection) as well as communication corruption (simple line noise,
local computation/prediction error, man in the middle, whatever).

  3) When objects are not members of the other's direct working set,
stop sending state change messages.

-- 
J C Lawrence                              Internet: claw#kanga,nu
(Contractor)                             Internet: coder#kanga,nu
---------(*)                    Internet: claw#under,engr.sgi.com
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