[Opensim-dev] Always mutable assets in OpenSim -- does it make sense?

[Mike Mazur]

Hi,

On Sun, 14 Dec 2008 09:10:24 -0500
Sean Dague <sdague at gmail.com> wrote:

> Mike Mazur wrote:
> > I'm curious whether it may be beneficial to make assets mutable.
> > AFAIK assets are currently immutable because of a LL decisions
> > early on to re-use one asset instance for very popular items sold
> > no-modify. This makes sense for them because they can:
> > 
> > * clean up unused assets since they own the entire infrastructure
> > (regions & DBs)
> > * save on space because they anticipate more identical copies rather
> > than slightly modified copies
> 
> I think you are discounting getting the asset to the client.  This
> isn't just an issue of things we can change.  If you update an asset,
> any clients out there with that asset id already won't see the
> changes using any of the current full featured clients.

I see. Getting around this in the SL client is (pretty much) impossible,
agreed.

The new clients, though, are being developed by other members of the
community and are under friendlier licensing terms. I'm sure they
could implement regular caching strategies, like today's 2D web
browsers do.

In fact, we can do one better than today's browsers. Because each
connected client is known by the server, the server could inform the
client when an asset has been updated. At this stage the client
requests this asset again, updating its cache.

If you can, I encourage you to read "Scalable User Content Distribution
for Massively Multiplayer Online Worlds" by Carl Symborski[1].
Unfortunately, it's not freely available online.

The article describes a method of first transferring a skeleton of the
world to the client. The skeleton contains metadata about the world,
such as last modification time or the hash of an asset. The client can
then determine whether it needs to request a particular component from
the server, or whether it can re-use information from its cache. This
approach can be extended beyond simply assets to all the content in the
region.

To me this looks like an opportunity for open source virtual worlds to
innovate ;)

Thanks,
Mike


[1] Carl Symborski, "Scalable User Content Distribution for Massively
Multiplayer Online Worlds," Computer, vol. 41, no. 9, pp. 38-44,
September, 2008.
http://www2.computer.org/portal/web/csdl/magazines/computer#4