[oslc-core] missing oslc query functionality

[Arthur Ryman]

Joe,

The query language was scoped to be simple to implement. It is not 
intended to be a fully general query language. For more complex 
requirements, services can implement a standard query language. SPARQL is 
recommended.

1. Correct. What semantics do you want for multi-value properties? Are you 
looking for the existence of one value that does not equal the given 
value?

2. Correct. However, you could approximate this effect by comparing the 
property to a value that you are sure does not exist. e.g. if ex:estimate 
is always non-negative, then ex:estimate > -1 would return resource that 
had any value for ex:estimate.

Regards, 
___________________________________________________________________________ 

Arthur Ryman 

DE, Chief Architect, Reporting &
Portfolio Strategy and Management
IBM Software, Rational 

Toronto Lab | +1-905-413-3077 (office) | +1-416-939-5063 (mobile) 





From:
Joe Ross <joeross at us.ibm.com>
To:
oslc-core at open-services.net
Date:
07/12/2012 06:39 PM
Subject:
[oslc-core] missing oslc query functionality
Sent by:
oslc-core-bounces at open-services.net



We've had a couple of scenarios that don't seem to be addressable using 
the OSLC core 2.0 query syntax: 

1. Finding all resources that don't have a particular value for a 
property. 
The != operator won't work for this, because in the case of multi-valued 
properties, records will be returned as long as there is a value that is 
not equal, even if there is also a value that is equal. This would require 
a unary "not" logical operator. 

2. Finding all resources that have any value for a particular property 
(matching on predicate, regardless of value). 
This is probably would probably be best handled by a unary "exists" 
operator, or support for wildcard as the value in oslc.where clauses. 
Currently the grammar seems to only allow for wildcard for the predicate. 

So, am I correct in this assessment? If so, was this omission intentional 
(and if so what was the reason), or an oversight? 

================================================
Joe Ross/Austin/IBM, joeross at us.ibm.com
Tivoli Autonomic Computing & Component Technologies
512-286-8311, T/L 363-8311_______________________________________________
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