[Opensim-dev] JSON or XML for serialization in the OpenSim database?

Tue Jul 6 10:06:07 UTC 2010

My 2cents:

The most important thing here is to make sure there is a mechanism in 
place for alternative formats. Personally, I have no preference for any 
format; the best format depends on the context of the application. Since 
we are doing a framework, we must assume that these applications will 
exist in a variety of contexts. Hence the absolute requirement that we 
will be able to plug in whatever serialization procedure we want.

On 7/5/2010 6:08 PM, Dahlia Trimble wrote:
> If it's using the OSD serialization methods in libomv, then there are 
> several serializations available, including XML, JSON, and a binary 
> format. I've used all three in projects and I've found the XML to be 
> the most robust and mature. Depending on the version of libomv 
> included with OpenSimulator, there may be bugs in formats other than XML.
>
> Would any of the formats reduce the need for on-the-fly conversion 
> between database and viewer? If the messages sent to the viewer are 
> XML then I don't see JSON as a candidate, especially since we've used 
> XML as a storage method in the past.
>
>
> On Mon, Jul 5, 2010 at 4:23 PM, Teravus Ovares <teravus at gmail.com 
> <mailto:teravus at gmail.com>> wrote:
>
>     Not a whole lot of feedback here yet, maybe people are on a long
>     weekend type camping vacation..
>
>     I'm partial to OSD/json, myself.    I'd also like to, at some point,
>     get a version number in there along with a definition of the format
>     for people who want to write integration tools..    however, that last
>     bit may be more of a 1.0 thing.
>
>     I think a lot of tools are going to go the way of JavaScript in the
>     future for various reasons...   one being that..   it's generally
>     implemented in all web enabled devices.   Computers, 'tablets', 'smart
>     phones'...   Another reason is it's more compact, while still being
>     fairly human readable.     One last reason that I can think of at this
>     moment is there are no external dependencies that 'get lost and turn
>     into a 404', like with XML Schemas.   I've done several XML based
>     integrations using REST and noted that in 55% of the cases, the
>     defining schema is a 404 which makes validation and automatic creation
>     of XML Serialization classes impossible.  Worse, in 15% of the cases,
>     extensions are defined in the schema and then used in the XML..  Only,
>     you won't ever know what tags and parameters the extensions provide
>     because the schema is 'missing'.
>
>     Regards
>
>     Teravus
>
>     On Sun, Jul 4, 2010 at 8:28 PM, Justin Clark-Casey
>     <jjustincc at gmail.com <mailto:jjustincc at gmail.com>> wrote:
>     > Hi folks,
>     >
>     > As part of the media-on-a-prim implementation, I'm serializing the
>     > parameters for a media texture to the database.  This seems
>     better than
>     > creating new database fields or even a whole new table for these
>     parameters,
>     > both because there are lots of them (url, scaling, controls,
>     whitelist,
>     > etc.) and because different future virtual environments may want
>     to store
>     > different things.
>     >
>     > I'm going to serialize them as an OSDArray or MediaEntrys using the
>     > libopenmetaverse library.  However, the question then becomes
>     whether to use
>     > the JSON representation or the XML representation.
>     >
>     > I tend to prefer XML for storage representations.  I believe
>     that it's
>     > somewhat more human readable and that there is better tool
>     support for
>     > manipulating it.  However, I know other people would prefer
>     storage in JSON
>     > and I accept that serialization/deserialization there may be
>     slightly
>     > faster.
>     >
>     > The only other example of serialization that I know of in
>     OpenSim currently
>     > is that of SceneObjectGroups into inventory, which encompasses
>     object
>     > properties, object inventory properties and script state.  This
>     is done in
>     > XML and media entries would become part of that serialization.
>     >
>     > If there's a majority preference for JSON I don't mind using
>     that instead,
>     > though I would want a justification for going this route rather
>     than XML.
>     >  If there's no real argument then I will go with XML.
>     >
>     > Also, I believe that we should try and be consistent, so picking
>     one or the
>     > other now should make it more likely that the same approach
>     would be used
>     > for the next serialization case.
>     >
>     > Regards,
>     >
>     > --
>     > Justin Clark-Casey (justincc)
>     > http://justincc.org
>     > http://twitter.com/justincc
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