[Zope3-dev] Re: RDFLib and Zope 3

[Daniel Krech]

On Sep 1, 2005, at 11:00 AM, Florent Guillaume wrote:

> Gary Poster wrote:
>
>> On Aug 23, 2005, at 8:07 PM, Michel Pelletier wrote:
>>
>>> On Tue, 2005-08-23 at 18:04 -0400, Gary Poster wrote:
>>>
>>>
>>>
>>>> The relationship between ZODB content objects, their int id as
>>>> provided by the pertinent intid utility, and a (theoretical)
>>>> corresponding RDF URI is what I'm having a hard time not making  
>>>> hacky
>>>> in my mind.  I'll think about it some more.
>>>>
>>>>
>>>
>>> They might not be that hacky, this might be the wrong direction  
>>> to  take
>>> but URI's don't have to be visually meaningful, blank nodes, for
>>> example, are usually just '_:' concatenated to a random opaque  
>>> string.
>>> If the URI were 'zope:XXXXXXXX' (maybe path/to/intid/ 
>>> util:XXXXXXXX)  that
>>> would work just as well, it would also be trival to transform into a
>>> feasible join key if the URI was also a URL that looked up,  
>>> instead of
>>> some network resource, an intid.
>>>
>>> Actually being able to trivially transform an intid to an rdflib URI
>>> might be something to think about.  Thinking about it more, the   
>>> current
>>> Zemantic uses the physical path of the object as the rdf:about=""  
>>> URI
>>> when an object adds itself, because honestly I could think of no  
>>> other
>>> URI in Zope.  This is obviously wrong, but I didn't have a  
>>> better  answer
>>> in paris.  Why not use the `intid` plus some URI sugar?  If the  
>>> URI  and
>>> the intid can be easily converted from one to the other then  
>>> that  should
>>> solve the whole problem, no?
>>>
>
> Here's another way to work with intids that I think could work:
>
> In rdflib in some backends like IOMemory, and internal id is found  
> for a subject (or predicate or object) to use in the internal  
> storage datastructures. rdflib uses some randid() for that.
>
> I propose that instead of calling randid(), it called self.assignid 
> (subject) which would be pluggable. By default this would be the  
> default randid, but you could allow Zope to create a graph with an  
> assignid that assigned ids based on the intid service.

This should definitely work for BNodes and think it can work for  
URIRef and Literals (will just need a second to think about it). I'll  
definitely keep this in mind as we're formalizing the interfaces with  
zope.interface -- which hopefully we can get a first cut done this  
weekend.

> Then if a subject or object passed to rdflib is an integer instead  
> of a URI, it would be used directly. In effect you'd give access to  
> the internal ids.
>
> (There are more details to solve (assignid needs to check for  
> collisions sometimes), but I think that's a good starting point).

I agree. We'll give it a go.

> Florent
>
> -- 
> Florent Guillaume, Nuxeo (Paris, France)   CTO, Director of R&D
> +33 1 40 33 71 59   http://nuxeo.com   fg at nuxeo.com
>

Daniel Krech, http://eikeon.com/