[Zope3-dev] Re: RDFLib and Zope 3

[Florent Guillaume]

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.

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).

Florent

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