[oslc-core] Oslc-Core Digest, Vol 11, Issue 24

Tue Dec 14 19:08:23 EST 2010

I think this confirms that the only safe option for a client is to assume
nothing. I think the spec should say this. I don't think it's even safe to
assume that "the resources that you get from a service that claims to
comply with a domain spec must comply with that domain spec". Let's assume
I'm a client that is programmed to understand version n of the XYZ OSLC
specification. If I access an XYZ service, I might find resources created
from version 1 through version n+m of the domain spec stored within the
same service, so it probably isn't even meaningful to talk about the
version of the service, unless it means simply the version of its
service/service provider document. Since I can't know in advance what
changes were introduced in versions n+1 through n+m, I can't really say
what it means for the resources to be compliant with a spec, so I'd better
be prepared for the unexpected.

Best regards, Martin

Martin Nally, IBM Fellow
CTO and VP, IBM Rational
tel: +1 (714)472-2690

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  |Arthur Ryman <ryman at ca.ibm.com>                                                                                                                   |
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  |Martin Nally/Raleigh/IBM at IBMUS                                                                                                                    |
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  |oslc-core at open-services.net, oslc-core-bounces at open-services.net                                                                                  |
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  |12/14/2010 06:50 PM                                                                                                                               |
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  |Re: [oslc-core] Oslc-Core Digest, Vol 11, Issue 24                                                                                                |
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Martin,

When Jim raised this topic initially, I pointed out that OSLC does not
currently make any statement about how type URIs should be used outside
their domain specs, i.e. you should assume that the resource satisfies the
domain spec. All you can count on is the service, i.e. the resources that
you get from a service that claims to comply with a domain spec must
comply with that domain spec. However, it does seem natural that the type
URIs (and any other property URIs) defined by one domain might be useful
to other domains or other non-OSLC services. Since these type URIs are in
the OSLC namespace, it seems appropriate that OSLC should specify their
intended use, with the usual understanding that no organization can
restrict how other organizations use URIs.

No, I didn't consider versioning. I assume the versioning rules are
specified by each domain and so any user of the type URIs should comply
with that. Yes, this could be a can of worms when a resource has more than
one type URI since you'd have to specify the versions for each of the
domains. This is a great topic for the "Mutli-Type" workgroup to discuss.

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

From:
Martin Nally <nally at us.ibm.com>
To:
oslc-core at open-services.net
Cc:
oslc-core at open-services.net, oslc-core-bounces at open-services.net
Date:
12/10/2010 11:30 AM
Subject:
Re: [oslc-core] Oslc-Core Digest, Vol 11, Issue 24
Sent by:
oslc-core-bounces at open-services.net

>> the RDF representation of T SHOULD satisfy the OSLC Domain
specification
that defines T.

Have you thought about what this means for versioning? Does this mean the
2.0 version of the OSLC specification? All past and future versions? I
think this will open a can of worms. I think we should make the opposite
statement - that when something says it is of some OSLC type, this carries
no guarantees whatever. Caveat emptor.

Best regards, Martin

Martin Nally, IBM Fellow
CTO and VP, IBM Rational
tel: +1 (714)472-2690

  From:       oslc-core-request at open-services.net

  To:         oslc-core at open-services.net

  Date:       12/09/2010 12:00 PM

  Subject:    Oslc-Core Digest, Vol 11, Issue 24

  Sent by:    oslc-core-bounces at open-services.net

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Today's Topics:

   1. Re: Resources that have Multiple rdf:type Values (Arthur Ryman)

----------------------------------------------------------------------

Message: 1
Date: Wed, 8 Dec 2010 17:25:40 -0500
From: Arthur Ryman <ryman at ca.ibm.com>
To: Dave <snoopdave at gmail.com>
Cc: oslc-core at open-services.net
Subject: Re: [oslc-core] Resources that have Multiple rdf:type Values
Message-ID:

<OFBE176E2F.3D444635-ON852577F3.007A354B-852577F3.007B3507 at ca.ibm.com>
Content-Type: text/plain; charset="US-ASCII"

Dave,

I was pointing out the status quo. However, our desire is that types be
used in a predictable way.

I am recommending that we add an explicit statement to our spec to avoid
"capricious" use of OSLC-defined types. We don't "enforce" this via an
ontology so we need to provide explicit guidance in the Core spec.

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

From:
Dave <snoopdave at gmail.com>
To:
Arthur Ryman/Toronto/IBM at IBMCA
Cc:
oslc-core at open-services.net
Date:
12/08/2010 04:56 PM
Subject:
Re: [oslc-core] Resources that have Multiple rdf:type Values

On Wed, Dec 8, 2010 at 12:22 PM, Arthur Ryman <ryman at ca.ibm.com> wrote:
> At the Core telecon today, Jim raised this topic. We need to continue
the
> discussion. Here is a suggestion for how to handle this:
>
> Any RDF resource representation MAY contain zero or more triples that
have
> a given URI, S, as the subject, and rdf:type as the predicate,  If there
> is a triple of the form (S, rdf:type, T) where T is a type URI defined
by
> some OSLC Domain specification, then the RDF representation of T SHOULD
> satisfy the OSLC Domain specification that defines T.

I thought you argued against this point today, saying that you can
only make that sort of inference when you that a resource is provided
by a service that implements an OSLC specification.

- Dave

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