Fwd: Persistence and worldbase server

> From: Howard Stearns <[hidden email]>
> Date: January 21, 2006 10:00:05 AM CST
> To: Hans N Beck <[hidden email]>
> Subject: Re: [croquet] Persistence and worldbase server
>
> I think in terms of in- and out-of-band:
>
>    Objects in or within Croquet are live objects situated in  
> context. You poke at them and they respond according to their  
> abilities, other objects can be affected, and everyone else sees  
> these effects.
>
>    But Croquet is part of a larger context of computers and the  
> Internet at large.  For example, you can have a Jabber chat window  
> within Croquet, and use this to communicate 'out-of-band' with  
> people who are not using Croquet.  And you can go around  
> serializing the state of Croquet objects and put them in an  
> external database. You can query such a database and unserialize  
> the data back into Croquet as different copies. The distinction (in  
> my mind) is that the out-of-band stuff aren't live objects situated  
> in context.
>
> Jasmine already has a basic out-of-band Worldbase interface. The  
> University of Minnesota runs an open SQL server for experimental  
> use, and you can use that as a model and set up your own to meet  
> your needs.
>
> Among the most important things about Hedgehog is that Croquet  
> worlds are persistent in a way that preserves the liveness of  
> objects and their context:
>    You can create, modify and delete objects in a virtual world and  
> then go away. When you come back later, everything is as you left it.
>    People can can come and go from the virtual world at any time,  
> and the liveness and context is preserved consistently among the  
> participants.
>    You can serialize the whole virtual world at the current time  
> and do what you like with it, such as storing it out-of-band, and  
> resurrecting it later as a twin or parallel world.
>
> There are (at least) two ways of combining these two concepts:
>
>    You can have a live object in Croquet that is proxy to an out-of-
> band service.  For example, our group is working on live,  
> persistent, Croquet objects that display, say, a given Web site or  
> Word document. In your case, you might have, say, writeable text-
> display proxy objects in Croquet.  The actual text would come from  
> an out-of-band database, and when you write on the display, the  
> database would get updated.  Croquet itself would persist only the  
> identifying information to access the database, from which it would  
> get the text to display.
>
>    The other way around would be to have very ordinary objects in  
> Croquet -- not proxies -- but which are identified by a sort of  
> URI. This would include a GUID for the world and a UID for the  
> object within that World. (Hedgehog will be able to do this, such  
> that given such a URI, you can participate in that world and work  
> with the specified object.)  Given this, you could create an  
> external database using metainformation about the objects you are  
> interested in, identifying them by this URI.  A query proxy object  
> in Croquet could then present the actual Croquet objects (not  
> serialized copies) as results, thus preserving liveness.  There are  
> issues. For example, if the original object and the object as query  
> result are both to be shown within the same 3D scene, then we have  
> to be able to have multiple views of the same original object, and  
> then you have decide which things (like global position) are  
> properties of the view and which (like text) are properties of the  
> model.  We're working on this, but I imagine that this may be  
> overkill for your needs.
>
> On Jan 21, 2006, at 3:50 AM, Hans N Beck wrote:
>
>> Hi,
>>
>> a question to persistence and worldbase servers (not shure if this  
>> occured already in this list):
>>
>> what kind of persistence  - if any - provides the next available  
>> release ("hedgehog", 1.0) ? I've something read about worldbase  
>> servers, but it sounds like  a big solution for big networks. But  
>> I want to use maybe 5 instances of Croquet in a closed team for  
>> storing and searching issues (requirements or feature requests for  
>> example), what can I do in this case ?
>> (That the image itself provides some kind of persistence  is  
>> clear, but one great value of databases is making queries )
>>
>> Regards
>>
>>
>> Hans
>>
>