[Opensim-users] Consequences of vicinity

[Diva Canto]

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