[Opensim-users] Consequences of vicinity

[Frank W Sweet]

The present HG "link-region" console command is, of necessity, a
temporary expedient. In a few years, there may well be tens of
thousands of independent stand-alone sims out there (mostly roleplay,
formal education, or corporate training). Users will need to TP among
them as easily as they link between web pages today. The appropriate
analogy for HG-TP is the html link.

Today's HG "link-region" console command demands sim owner involvment.
This is as infeasible as asking a website owner to let you link out of
her website. Instead, HG-TP must be made dynamic. The destination
region must be notified to prepare only when the use actually clicks
on TP-out, and the actual TP initiated only after that first step.

Users will never fly (or walk or drive) from one standalone region (or
one grid) to another. Hence, there is no need to notify every
conceivable destination sim (no matter how near or far grid-wise) that
user-A has logged on somewhere. Instead, only the immediate target
region of an initiated HG-TP should be notified, and that notification
should then be immediately followed by the incoming user.

That way, only those users actually present at the UCI Welcome region,
plus those inbound in transit, will spawn child agents in the region
(rather than spawnng child agents for every user in every linked sim). 
True, even these agents may still overload the region if it is
extremely popular. But that is a problem that we already know how 
handle.

Frank W. Sweet
Backintyme Publishing

----- Original Message ----- 

Message: 5
Date: Mon, 29 Dec 2008 11:16:00 -0800
From: Diva Canto <diva at metaverseink.com>
Subject: [Opensim-users] Consequences of vicinity
To: opensim-users at lists.berlios.de
Message-ID: <495921F0.9010306 at metaverseink.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi,

As we move opensim into a truly decentralized system, with things like
the Hypergrid, but also grids like OSGrid, it is important for people
to
understand what space vicinity really means, and the consequences of
neighboring someone. I thought I'd write this in an email, to reach
the
wider number of opensim users.

One of the main features of these 3D VWs is the continuity of 3D space
in a logical grid. That is, you are in a region but you can see the
things that are in neighboring regions, even when those neighboring
regions are running on machines half-way across the globe. You can
cross
to your remote neighbors as if you were crossing to a region on your
machine, etc. That's all very nice, but...

This model is taken from massive multi-player on-line games *that are
controlled by single organizations*. Things need a lot more
consideration when we go to a decentralized control system. Let me
explain why.

The illusion of space continuity is achieved by spawning computations
on
your neighbors' machines (and your neighbors' on yours). This is done
via inter-simulator communications, that start and manage what is
known
as "child agents". There are a number of consequences of this:

1) As we work on inter-simulator communications, if your neighbors
aren't exactly on the same version of OpenSim that you are, things may
break badly for you.

2) For HG, if you place an hyperlink next to your region, it will
create
child agents on that remote simulator. For example, if everybody would
place the UCI Welcome region as a direct neighbor, the poor UCI
Welcome
region would have hundreds of child agents -- the number of
hyper-neighbors is not restricted to 8.

For the HG, distance is not enforced (yet), but it may very well be
enforced soon.

For grids like OSGrid, I strongly advise people who want some form of
stability while using SVN Head (ah!) to keep distance from their
neighbors. Inter-sim comms are about to go through a period of change.

Crista