[oslc-cm] Updated State Predicates Proposal

[Steve K Speicher]

> From: Samuel Padgett/Durham/IBM
> To: Paul McMahan/Raleigh/IBM at IBMUS, 
> Cc: oslc-cm at open-services.net, oslc-cm-bounces at open-services.net, Steve 
K 
> Speicher/Raleigh/IBM at IBMUS
> Date: 06/20/2012 06:32 PM
> Subject: Re: [oslc-cm] Updated State Predicates Proposal
> 
> > From: Paul McMahan/Raleigh/IBM at IBMUS
> >
> > The consumer needs to know if state predicates are supported because
> > otherwise the query results could be unpredictable.   For example, if 
a
> > consumer sent a query like oslc.where="oslc_cm:closed=true" then one
> > service provider might include ALL of the change requests in the 
result but
> > another service provider might include NONE, depending on their
> > interpretation of the spec.

> Hey, Paul. My understanding of this scenario is that the query should 
never 
> return any results if the provider doesn't support predicates because no 

> resources will ever have that triple. I don't think it's ambiguous, 
although
> I agree some providers could get it wrong.

What if the results of the query are really no results, even if the 
provider supports it?  Even in the case of using oslc.select and the query 
returns 0 results, the selected property wouldn't be in the response due 
to no results.  Just an observation.

> We could offer that guidance here in the CM spec, but I still feel it 
should
> be in the Core query spec since it's not specific to predicates. It 
applies 
> to any property that a particular provider doesn't support. We still 
have an
> open Core issue on this, Issue 42 [1].
> 
> I agree with Steve that the simplest way is to use 
> oslc.select=oslc_cm:closed and see if the triples are in the response.
> 
> [1] http://open-services.net/bin/view/Main/OslcCoreV2Issues