[Opensim-dev] SceneObject* Metadata

[Justin Clark-Casey]

Frisby, Adam wrote:
> Well,
> 
> If we save it in RexEntity - then every storage provider needs to recognise it. RexEntity does and will exist - however when it comes to packaging the data up and putting it in a storage provider, we then need to make customised versions for each. The metadata field provides a convenient way of storing the extra properties in a backwards compatible way.
> 

Is a mesh UUID really metadata?  I agree with Melanie - it would seem to be more a property of the object than metadata 
about the object.  I also see it being generally useful, so I would argue that it would merit a proper column in a 
region db table.

I imagine the entire Metadata dictionary would need serialization into a single column in the regions table.  There 
would inevitably be a performance cost associated with packing and unpacking such a structure.  However, I do see that 
one might be generally useful and even necessary for other types of data.

Regarding serialization formats for storing inventory - these will need to evolve.  It's already proving to be 
problematic in any elimination of SOG or general code refactoring (since there's a <SceneObjectGroup> tag in there and 
everything).  I'm wondering if it wouldn't be better to have separate code serializing SOP rather than just using .NET's 
object serialization - I think Stefan may have suggested this a couple of times in the past.  Those damn things also 
really need to have a version number embedded in them, I think.

> Adam
> 
>> -----Original Message-----
>> From: opensim-dev-bounces at lists.berlios.de [mailto:opensim-dev-
>> bounces at lists.berlios.de] On Behalf Of Melanie
>> Sent: Wednesday, 26 November 2008 4:58 AM
>> To: opensim-dev at lists.berlios.de
>> Subject: Re: [Opensim-dev] SceneObject* Metadata
>>
>> Hi,
>>
>> ideally, Rex data should be in a RexEntity, not the LLEntity or
>> IEntity.
>>
>> I'm +1 on the metadata as such, but I think meshes should not be
>> metadata. As a stopgap measure maybe, but not as an architectural
>> choice.
>>
>> Personally, I see no call to bend over backwards for Rex, What have
>> they done for the project or me lately?
>>
>> If we do change the serialization stuff, let's please make the
>> format accommodate coalesced objects, too?
>>
>> Melanie
>>
>>
>> Frisby, Adam wrote:
>>> Hi everyone,
>>>
>>> I'd like to add another parameter onto SceneObjectPart and group
>> called 'Metadata' - Metadata would be a Dictionary<string,string> which
>> is serialised with the object when loaded and saved from inventory,
>> archives, etc.
>>> This change would require all the storage providers to handle the new
>> metadata fields. The purpose of this field is mainly to support things
>> that the stock OpenSim parts do not - without breaking compatibility.
>>> An example of such usage would be a "MeshUUID" metafield for the
>> Modular Rex components we're building inside DeepThink - this would
>> allow the Rex metadata to be attached to a otherwise normal field, but
>> would only be understood and handled by the simulator if you had the
>> modular rex components installed.
>>> Another example might be tagging keywords for search and indexing
>> purposes, AI, etc. All the metadata properties would be accessible from
>> region modules and they can write and add new ones relatively easily
>> under the proposal. (Just grab the SOG/SOP, then edit the metadata
>> dictionary).
>>> Thoughts?
>>>
>>> Adam
>>>
>>>
>>>
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Justin Clark-Casey
http://justincc.wordpress.com