[Versa] Question about query

[Michael Olson]

On Sep 4, 2005, at 10:07 AM, Uche Ogbuji wrote:

> On Thu, 2005-09-01 at 12:15 -0600, Michael Olson wrote:
>> On Sep 1, 2005, at 12:02 PM, Chimezie Ogbuji wrote:
>>
>>>> The following is a legal expression in Versa:
>>>>
>>>>    <http://foo.com>
>>>>
>>>
>>> This doesn't look like current Versa syntax for identifying resources
>>> (unless you had the previously suggested <..uri ..> form in mind -
>>> from N3), so I'll assume you meant (@'http://foo.com').
>>
>> see
>> http://lists.fourthought.com/pipermail/versa/2005-August/000086.html
>> and issue 1010 in the issue log.
>>
>> Since I've received no objections to the proposal I've moved it to
>> accepted so it is valid next gen versa.
>
> I don't think this is proper procedure.  Even when we've all three
> caught up on all threads, all we have is a set of proposals.

Then what is proper procedure?  WRT N3 syntax all three of us have  
stated that we agree it should be in there.  So I added it.

>
> For sure, I don't agree with everything you have in your draft of Versa
> 2.0.  I think we have a decent amount of discussion to continue.
>

I wrote the draft because I was not getting any (except some from  
Chime) response to my questions.  I figured the best way to proceed was  
to put out my thoughts and see what people think.

I think we have less to discuss then you imply, here is a run down of  
the changes to the spec and where I think we are at.

1)  move toward N3 syntax.  No objections to this at all.
2)  addition of the declarations section to a query.  I think we are  
pretty much at agreement here except for the next tiem
3)  addition of a "scope" for a query.  I think we agree that we need  
to have these, just need to figure out how to spell them.
4) addition of exitensial filter and traverse, no objections
5)  addition of operators ie < > !=.  No objections, just a  
clarification you made.
6)  resource/literal queries vs patterns.  This is about the biggest  
point I think we need to resolve, should we support top level queries  
of this form.


> And we also have to remember to throw things out for public discussion.
>

I do.  So far public discussion has been you, me and Chime.

> So we don't have anything at all that is "valid next gen versa".
>
>

Sure we do.  We have a proposed next gen versa (even if you don't agree  
with all of it it is proposed) and the above expression is valid in  
that grammar.


>> So are we in agreement, the following queries return an empty set if
>> the resource is not in the model:
>>
>> <http://foo.com/res>
>> @"http://foo.com/res"
>> foo:res
>
> What does it mean for a Versa resource data type to be the actual
> resource itself, and not just its name?  It hurts my head to try to  
> make
> sense of that.  I think these are just names, and therefore I draw the
> opposite conclusion.
>

Because a resource does not have to be named.  rdf:nodeID="x" is an  
unamed resource in XML.  An implementation needs a way to reference  
these internally.  the semantics document talks about "allocation of a  
blank node" but I wanted to avoid requiring the simple entailment in a  
versa implementation.

Mike

>
> --  
> Uche Ogbuji                               Fourthought, Inc.
> http://uche.ogbuji.net                    http://fourthought.com
> http://copia.ogbuji.net                   http://4Suite.org
> Use CSS to display XML, part 2 -  
> http://www-128.ibm.com/developerworks/edu/x-dw-x-xmlcss2-i.html
> XML Output with 4Suite & Amara -  
> http://www.xml.com/pub/a/2005/04/20/py-xml.html
> Use XSLT to prepare XML for import into OpenOffice Calc -  
> http://www.ibm.com/developerworks/xml/library/x-oocalc/
> Schema standardization for top-down semantic transparency -  
> http://www-128.ibm.com/developerworks/xml/library/x-think31.html
>
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Mike Olson                                                Principal  
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