[Opensim-users] grid operation

Thu Dec 4 18:36:40 UTC 2008

Kyle Hamilton wrote:
> Could someone please read
> http://opensimulator.org/index.php?title=OpenSim:Introduction_and_Definitions
> and fix any glaring errors or omissions I may have made?  There's a
> couple of TODO items therein (at least one needs examination by people
> familiar with Assets, Inventory, and how they're managed), and I'd
> like to solicit feedback on how I can write these kinds of things
> better.
> 

Nice stuff Kyle - this is a good start.  I made some edits and eliminated the TODOs.

On this subject, you might be interested in a blog post I wrote some time ago (but naughtily never transferred to the wiki)

http://justincc.wordpress.com/2008/04/17/opensim-tech-basics-opensim-is-brought-to-you-by-the-letters-u-g-a-i-and-r/

(though some of this info is probably out of date)

There is also another wiki page

http://opensimulator.org/wiki/OpenSim:TechRef

with some architectural description on it and links to other pages - not sure how fresh this is.

Is this intended to be for users or for developers?  If for developers, is it worth cross-posting to opensim-dev?

> -Kyle H
> 
> On Mon, Dec 1, 2008 at 12:42 AM, Stefan Andersson <stefan at tribalmedia.se> wrote:
>> Really, if somebody would be so excellent as to take this whole thread, and
>> out of the questions and answers on it, make a wiki page, called
>> 'OpenSim:Introduction and Definitions' or something, that would be SO
>> golden.
>>
>> You seldom get these opportunities to learn from noob confusion. This is an
>> excellent thread.
>>
>> Best regards,
>> Stefan Andersson
>> Tribal Media AB
>>
>> Join the 3d web revolution : http://tribalnet.se/
>>
>>
>>
>>
>>
>>
>> ________________________________
>> Date: Sun, 30 Nov 2008 13:16:35 -0800
>> From: diva at metaverseink.com
>> To: opensim-users at lists.berlios.de
>> Subject: Re: [Opensim-users] grid operation
>>
>> Yes, those are all functions of the 3D space service currently. Scripting
>> and backend modules provide programmable behavior for the objects and agents
>> in the 3D environment.
>> The scripts are stored in the asset server, just like all other assets. They
>> are brought in to the region when the region starts and run on the same
>> process that runs the region. When you create a new script in a region, that
>> script is cached in that region's asset cache (in memory), and is sent to
>> the asset server for persistent storage.
>>
>> This is the current architecture. I remember vaguely someone suggesting to
>> move the script engine(s) to a different server, as an alternative physical
>> architecture. In that case, the region wouldn't cache the scripts, they
>> would go to that other server; only the effects of the scripts would be seen
>> inworld. Not sure how far that idea went.
>>
>> This thread is making suspect that many people might be under the wrong
>> impression that just because they have their own region server connected to
>> someone's grid, they have 100% control over the assets in the region and
>> even in their inventories. That is not correct. The persistent storage of
>> everything is done in the grid-level servers, therefore under the control of
>> whoever runs those servers. If the asset server kaputs, and there were no
>> backups, you will loose just about everything you have in your region and in
>> your inventory. (This is true independent of who has the control over the
>> asset server, so maybe it's a good thing to have them on someone else's
>> asset server, you can blame someone else :-)
>>
>>
>> Dickson, Mike (ISS Software) wrote:
>>
>> Well, it's running scripts for prims in the region also isn't it…  And
>> physics for physical items in the scene the region is managing. (These are
>> assumptions, feel free to clarify, like Paul I'm trying to learn.)
>>
>>
>>
>> Mike
>>
>>
>>
>> From: opensim-users-bounces at lists.berlios.de
>> [mailto:opensim-users-bounces at lists.berlios.de] On Behalf Of Diva Canto
>> Sent: Sunday, November 30, 2008 11:36 AM
>> To: opensim-users at lists.berlios.de
>> Subject: Re: [Opensim-users] grid operation
>>
>>
>>
>> Right.
>> When your region is connected to a physical grid, your region is *just* a 3D
>> space server, nothing else.
>> All assets belong to the asset server, all inventories belong to the
>> inventory server, all users belong to the user server.
>>
>> Paul Fishwick wrote:
>>
>> Got it. So, the data are stored on the asset server. If this is
>>
>> so, it doesn't seem that my region server (the opensim instance
>>
>> I might run as part of someone's grid) is doing much of
>>
>> anything since any change in prim or agent attribute must be
>>
>> conveyed back to the grid's asset server.
>>
>> -p
>>
>>
>>
>> Diva Canto wrote:
>>
>>
>>
>> By "assets" I mean the data itself, the blobs/text/etc.
>>
>> The region prims/primitems storage holds only references to that data.
>>
>>
>>
>> Look inside OpenSim.db. There is no "data" there, only meta data and
>>
>> references to the data (by UUID) stored on the asset server.
>>
>>
>>
>> Paul Fishwick wrote:
>>
>>
>>
>> When you say the prims and primitems are not assets, I am confused.
>>
>> My understanding was that all items are assets, identified by their unique
>>
>> UUIDs. If I follow the point about the asset server, the asset servers
>>
>> stores all asset UUID references by region, but that the specific asset
>>
>> attributes (i.e., position of an object, or its texture) are stored by UUID
>>
>> in the region's DB?
>>
>> -p
>>
>>
>>
>>
>>
>> Diva Canto wrote:
>>
>>
>>
>>
>>
>> The asset server holds the assets for the entire collection of regions
>>
>> on that physical grid. For example, when you create an object inworld,
>>
>> the asset corresponding to that object is stored on the asset server.
>>
>>
>>
>> The region caches some assets in memory. For example, in that creation
>>
>> scenario, the asset would be on the cache of the region too.
>>
>>
>>
>> The region also has a database storing "prims" and "primitems". These
>>
>> are not assets; they are the prims that are inworld at any given time.
>>
>> The prims refer to assets (by UUID) that are stored on the asset
>>
>> server. Which, as the previous sentence says, may be cached in memory
>>
>> of the region.
>>
>>
>>
>> Paul Fishwick wrote:
>>
>>
>>
>>
>>
>> Right. But what, exactly, are these servers doing?  I guess I am trying
>>
>> to get at more of the architectural details of what types of messages are
>>
>> sent among servers (over the network and to the database(s)). For
>>
>> example, there are the UGAIM servers in grid mode. Does the grid's "A"
>>
>> server hold all of the assets on your region that  you plugged into the
>>
>> grid? Or does your region database (on the same computer as your
>>
>> opensim.instance) take care of that?
>>
>> -paul
>>
>>
>>
>>
>>
>> Ideia Boa wrote:
>>
>>
>>
>>
>>
>>
>>
>> If you run 1 region in a grid, you only run OpenSim server, the others
>>
>> servers (User, Grid, Asset, Inventory and Message) are running on the
>>
>> Grid servers with the grid OpenSim server.
>>
>>
>>
>>
>>
>>
>>
>> Paul Fishwick wrote:
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> If one hooks a region to a grid, what functions does the
>>
>> region server (operating on your computer) perform? The
>>
>> Grid servers are running asset and inventory management,
>>
>> so does this mean that the grid A and I machines handle
>>
>> the assets and inventory or is that the function of the region
>>
>> server that connects to the grid?
>>
>> -p
>>
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>>
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>>
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>>
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>>
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>>
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>>
>>
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-- 
justincc
Justin Clark-Casey
http://justincc.wordpress.com