[oslc-core] Question on oslc query - absence of properties

[Arthur Ryman]

Ian,

Yes, that would be very useful. One approach to implementing this is to 
use aggregration, e.g. count. For example,

http://example.com/requirements?oslc.where=count(rm:satisfiedBy)=0

SQL implementations can handle this. Unfortunately, the current SPARQL 
spec does not support aggregration. However, this could be added as an 
extension but that would require spec and dev work. 

We'd have to add an oslc.groupBy query parameter too to make aggregation 
useful.

Regards, 
___________________________________________________________________________ 

Arthur Ryman, PhD, DE


Chief Architect, Project and Portfolio Management

IBM Software, Rational

Markham, ON, Canada | Office: 905-413-3077, Cell: 416-939-5063
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oslc-core-bounces at open-services.net wrote on 03/01/2010 05:02:59 AM:

> [image removed] 
> 
> [oslc-core] Question on oslc query - absence of properties
> 
> Ian Green1 
> 
> to:
> 
> oslc-core
> 
> 03/01/2010 05:08 AM
> 
> Sent by:
> 
> oslc-core-bounces at open-services.net
> 
> The draft query spec. doesn't seem to support queries involving absence 
of 
> properties .  For example, 
> 
>         find all requirements which do not have a satisfiedBy link
> 
> Do any ofher domains see the need for such questions to be supported by 
> OSLC Query?
> 
> Does anyone see any difficulty in extending OSLC query so that such 
> formulations would be possible?  (I think SteveS was looking at 
> "unsaid"/"negation by failure" at some point.)
> 
> best wishes,
>     -ian
> 
> ian.green at uk.ibm.com (Ian Green1/UK/IBM at IBMGB)
> Chief Software Architect, Requirements Definition and Management
> IBM Rational
> 
> 
>