Re: SPARQL vnext new feature? cascadedQueries

Is there a reason one would like to do a local subquery? Isn't it  
equivalent to something that you could write at top level with about  
the same number of characters?

-Alan

On Nov 4, 2007, at 7:55 AM, Steve Harris wrote:

> Well, that would be the obvious syntax for a local sub-query too.
>
> - Steve
>
> On 4 Nov 2007, at 12:48, Alan Ruttenberg wrote:
>
>> Although I intended that the specification of this was that it was  
>> only legal for an endpoint, as that's what makes it easy. I'm not  
>> sure it's a useful construct otherwise, as you don't need it  
>> nested in the FROM if you have to download the file.
>> -Alan
>>
>>
>> On Nov 4, 2007, at 7:38 AM, Alan Ruttenberg wrote:
>>
>>> Good point. Perhaps FROM ENDPOINT.
>>>
>>> -Alan
>>>
>>> On Nov 4, 2007, at 7:35 AM, Steve Harris wrote:
>>>
>>>> On 4 Nov 2007, at 04:09, Alan Ruttenberg wrote:
>>>>
>>>>> This is a particularly easy one, since it adds no new  
>>>>> expressivity. The form
>>>>> below can be syntactically transformed into SPARQL as specified  
>>>>> now by way
>>>>> of using the SPARQL protocol for the construct in the FROM.
>>>>> Since this is the only reasonable way we have to do federation  
>>>>> now, within
>>>>> spec, it's more like adding friendly syntactic sugar.
>>>>
>>>> As far as I can tell there's no way to tell that <http:// 
>>>> example.com/sparql?> is a SPARQL endpoint, rather that a graph  
>>>> served by a CGI script with no arguments.
>>>>
>>>> - Steve
>>>>
>>>>> On 11/3/07, Dan Connolly <connolly@w3.org> wrote:
>>>>>>
>>>>>> Alan Ruttenberg wrote:
>>>>>>>
>>>>>>> SELECT ?a ?b
>>>>>>> FROM ( CONSTRUCT { ?d <b> ?b }
>>>>>>>                         FROM < http://example.com/sparql?>
>>>>>>>                       WHERE { ?b <b> ?d } )
>>>>>>> WHERE { ?a <b> ?b }
>>>>>>
>>>>>>
>>>>>> Yes... the Data Access WG considered this sort of thing briefly;
>>>>>> we didn't see any particular reason not to do it but we...
>>>>>>
>>>>>> RESOLVED 2005-01-20: to postpone cascadedQueries; while  
>>>>>> federation use
>>>>>> cases are interesting, the designs don't seem mature and the  
>>>>>> use cases
>>>>>> are not urgent; with KendallC abstaining.
>>>>>> http://www.w3.org/2001/sw/DataAccess/issues#cascadedQueries
>>>>>>
>>>>>> I'm happy to see people playing around with it; I hope the
>>>>>> designs get mature soonish.
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Dan Connolly, W3C http://www.w3.org/People/Connolly/
>>>>>>
>>>>>>
>>>>
>>>
>>
>

Received on Sunday, 4 November 2007 13:05:03 UTC