[Opensim-users] Meta-data for IAR and OAR + Sharing

[Justin Clark-Casey]

On 18/06/10 23:47, Revlin John wrote:
> This is related to a thread from the dec '09 archives, "Re: OAR File
> Sharing Revisited", but I have some subject matter to add to the
> previous discussion that I don't think was directly addressed.
>
> The OAR & IAR file formats need a meta-data component, most likely
> XML-based. This would facilitate many file sharing capabilities, allow
> for some sort of version system AND, most importantly I think, allow for
> tracking relationships between OAR's. The last capability seems to
> relate back to "Re: OpenVCE OAR on Mega-Region?" thread from jan '10.

There actually is already a metadata file contained within OARs and IARs called archive.xml.  It doesn't act as a 
manifest but it does record version numbers for upward compatibility purposes.

>
> Right now there's no mechanism for tracking relationships between
> multiple OARs other than the archive's filename which tells almost
> nothing about contents of the archive. Dido for IAR. A Meta-data system
> of OAR/IAR archives should first and fore-most list the contents of the
> archive as well as additional meta-data for each of individual component
> of those contents. Version tracking is particularly useful  in the case
> where a second user wishes to edit and re-archive the contents of an
> OAR, which would be a kind of sim re-mix. The would also allow for
> saving/loading multi-region sims in ways that address some of the
> short-falls of the current megaregion scheme (terrain load-tile still
> isn't working on my server, but I digress...)

Not being able to save multi-regions is annoying and will ideally be fixed one day.  Loading/saving regions is 
unfortunately probably more complicated than simply load/saving the separate 256x256 spaces.

>
> I also think that the issue of sharing content is seperate from the
> issue of running the OpenSim server, meaning it should not be handled by
> another os module. All that the OpenSim server requires for loading new
> content from OARs and IARs is that the archive be placed in a folder
> under the bin heiarchy (I download OARs to bin/import/oar)  and then
> loaded via the server command line. This is a pretty simple mechanism,
> although some extra command line tools like the ability to list the
> contents of an archive before loading it (via meta-data component) would
> be extremely helpful.

Archives are actually just tar.gz files.  You can untar them and inspect their contents.  See

http://opensimulator.org/wiki/OpenSim_Archives

for more details.

>
> However, the issue of retreiving OARs and IARS from a remote location is
> another matter. What's needed is a  separate application for tracking
> and sharing OAR/IAR and it would naturally implement the above mentioned
> meta-data component. Given these needs it seem like an appropriate
> system might be something like a feed/subscription system, kind of like
> a podcast/aggregator app. Feeds allow an app to track updates to content
> without requiring the host system to actually download such content. The
> retreival process can be managed, customized and automated, much like
> the process of retrieving new and past episodes in a podcast feed.
> Although the podcast system is limited by centralization, I think an
> OAR/IAR feed system could implement some form of peer-to-peer
> distribution capability, as well as allowing for multiple
> creator/authors for a single feed (and multiple versions of a single
> OAR/sim).

I'm not going to address this point directly, but I will note that it's possible to load iars/oars on the command line 
from an URL as well as a file.

Any more complicated arrangement should almost certainly be left for tools outside OpenSim, imo.  There are hooks by 
which add-on region modules can call load/save oar/iar functionality.

>
> This would be awesome. My lexicon of technical terms kind of fails me
> when I think about the possibilities for OpenSim. If there's any
> interest in these ideas I'd love to have an extensive group discussion
> on the details of a potential implementation.
>
> play and have fun,
> Revlin
>
>
>
>
>
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Justin Clark-Casey (justincc)
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