[MUD-Dev] Re: TECH: Distributed Muds

Vincent Archer archer at nevrax.com
Fri Apr 20 09:26:35 New Zealand Standard Time 2001

According to Bruce:

> I've never really personally liked the models of transparent
> distributed communications between objects for roughly the same
> reason that I prefer message-passing over distributed shared memory.
> From my point of view, it seems that it is much easier to notice
> when you're doing a distributed operation when it isn't entirely
> transparent.  But, when it is transparent, you need a whole new set
> of tools to help monitor and debug what's going on in terms of
> frequency and number of distributed operations because it is too
> easy to add a distributed operation without realizing it, either
> because you simply didn't notice something in the docs, the
> implementation or the docs were lacking.

I recently had this point raised, but in a different domain. We were
looking for database work, and we got a few sales pitch. The one that
seemed the most interesting was for an object-oriented database, or,
as they say, a "permanent object store".

For those who don't know the heck an OO Database does, it's a form of
database in which you store objects. "All" you have to do is have said
object inherit a "permanency" class, and voila: your object is
permanent in the database. Whenever you reference one, it's pulled out
of the database and available. Modify it, and sometime later, it's
back there.  And what's even better, your object may reside in
different programs.

  "Ohhh" "Ahhh" (sounds within the minds of the local dev team)

A friend looked at what we were trying to do and said: "it's a trap".
Because you no longer know that objects are now in fact stored on
disk, and not resident in a process memory, you quickly fall into
traps. Like searching for an object by scanning a linked list. Ahhh,
but the linked list will quickly pull 1Gbyte of data in your process
just to find the object that has this property or that. And worse:
you're not conceptually aware of it. Until you try the program on the
real data, and finds out everything crawling at speeds that would make
an old 8086 seem a decent system :)

For those still interested in OO databases, I think there's one in
open source floating somewhere. Pretty nice for MUD developpers still,
since you no longer have to worry about how to store and load things.
But better hone that Detect Trap skill first.

Vincent Archer                                         Email: archer at nevrax.com

Nevrax France.                              Off on the yellow brick road we go!
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