[oslc-core] Ambiguity in Resource Shape definition + consequent questions

[Arthur Ryman]

John,

At our last telecon I took the action of suggesting clarifications for the 
spec text [1].

The current decription for oslc:describes is: 

Type or types of resource described by this shape. 

I suggest this description: 

This shape describes resources that are of any of these types. That is, 
the shape applies to resources that are in the union of the types. Note 
that if a resource has multiple rdf:type properties then the resource is 
in the intersection of those types. Therefore a shape S applies to a 
resource R if R has a type T and there is a triple S oslc:describes T.

Regards, 
___________________________________________________________________________ 

Arthur Ryman 

DE, PPM & Reporting Chief Architect
IBM Software, Rational 
Toronto Lab | +1-905-413-3077 (office) | +1-416-939-5063 (mobile) 





From:
John Arwe <johnarwe at us.ibm.com>
To:
oslc-core at open-services.net
Date:
01/11/2012 11:19 AM
Subject:
[oslc-core] Ambiguity in Resource Shape definition + consequent questions
Sent by:
oslc-core-bounces at open-services.net



[1] Defines the Resource Shape resource definition.  It includes the 
following property definition: 

> oslc:describes zero-or-many True Resource Reference n/a Type or types of 
resource described by this shape. 

Q1: This allows for multiple oslc:describes triples in a resource shape, 
but leaves open what the relationship is between these values and the 
(possibly multiple) rdf:type values in any given "described" resource 
instance (i.e. what condition(s) must be true in order for a given shape 
to describe a given resource instance appears to be under-specified). 
Breaking it down case by case, and stating what I *think* is the intent 
for each (looking for confirmation/disputes of this interpretation) with 
??? in cases where [1] really leaves me guessing.  I have implementation 
folks already interpreting the ??? cases differently, BTW.   

Q1a; 
RS oslc:describes = { Fred } 
resource instance RI rdf:type = { Fred } 
intent: RS describes RI 

other cases where both {}s have single values: RS does not describe RI 

Q1b; 
RS oslc:describes = { Fred, Wilma , Barney } 
resource instance RI rdf:type = { Fred }    (or { Wilma } or { Barney } , 
but only 1 in an instance) 
intent ???: RS describes RI 

??? other cases where RI {}s has a single values: RS does not describe RI 

(one alternative interpretation was that the type sets must be identical 
in order to say the RS describes the RI) 


Q1c; 
RS oslc:describes = { Fred, Wilma , Barney } 
resource instance RI rdf:type = { Fred , Bambam } 
intent ???: RS describes RI 

??? other cases where both {}s have  multiple values: RS describes RI iff 
at least one type URI is present in both sets (i.e. the intersection of 
types is non-empty) 




Q2: (editorial change I think) 
from: A Resource Shape describes the properties that are allowed or 
required by one         type  of resource. 
to:   A Resource Shape describes the properties that are allowed or 
required by one or more types of resource. 
Q3: Is oslc:describes cardinality of 0:n (specifically the lower bound) 
intended?  vs 1:n?  If 0 is the intent, would need to tweak Q2 
Q4: Another disagreement between the words and oslc:describes cardinality 
from: providing a machine-readable definition of an          OSLC resource 
type . 
to:   providing a machine-readable definition of one or more OSLC resource 
types. 
FWIW: I kept "resource type" there, but "resource definition" might be 
more in keeping with the rest of the specs' content... did not do a wide 
search. 
Q5: (editorial nit?) 
from: OSLC Creation Factory MAY provide a Resource Shape  ... create a 
resource 
to:   OSLC Creation Factory MAY provide   Resource Shapes ... create 
resources 
...and similiar one for Query Capability in the next sentence. 
Q6: (editorial nit?) 
from: A Resource Shape resource can have a title and a        type . 
to:   A Resource Shape resource can have a title and a set of types. 
("one or more" again would do equally well) 
[1] 
http://open-services.net/bin/view/Main/OSLCCoreSpecAppendixA?sortcol=table;table=up;up=#oslc_ResourceShape_Resource 

Best Regards, John

Voice US 845-435-9470  BluePages 
Tivoli OSLC Lead - Show me the Scenario 
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