[oslc-core] How will Resource Shapes be provided?

[Steve K Speicher]

Dave <snoopdave at gmail.com> wrote on 06/16/2010 03:46:54 PM:

> From: Dave <snoopdave at gmail.com>
> To: oslc-core <oslc-core at open-services.net>
> Date: 06/16/2010 03:50 PM
> Subject: [oslc-core] How will Resource Shapes be provided?
> Sent by: oslc-core-bounces at open-services.net
> 
> We expect that OSLC domain specifications will specify Resource Shapes
> for some resources. How will we provide these shapes and can providers
> extend them? Consider these two question:
> 
> 1) Should we make OSLC defined shapes available at open-services.net
> or do we expect that providers will each provide these shapes as part
> of their implementation? My opinion: we should do both. Make shapes
> available on open-services.net and recommend that allow providers to
> provide them as well.

We should provide them on open-services.net. Implementations can use this 
as the base of the shapes they need to serve up.

> 2) If we allow implementations to provide the specified shapes, what
> are the requirements? What changes are implementations allowed to
> make? Can they add new "custom" properties? I have two opinions on
> this one:
> a) Implementation must provide the OSLC Defined Resource shapes
> verbatim with no changes and no additional properties. Resource Shape
> Extensibility is a new feature not in the spec and we shouldn't add
> new features during convergence.
> b) Implementations must not remove or add any properties to an OSLC
> defined resource shape, but may add new custom properties. To prevent
> conflicts, for custom properties, implementations should define
> entirely new properties in an entirely implementation-specific
> namespace.

I think it is up to a domain spec to make it clear which ones are 
"required" to be supported.  I can see where there are some properties 
that make sense for all providers to support.  Though one way to discover 
whether an implementation supports some properties is whether or not they 
are in the shape.  Maybe we don't have a way to indicate this today, 
zero-or-many isn't quite right as the only option for a service provider 
to indicate it doesn't support a property is to use either zero-or-zero or 
omit it from the shape.

Thanks,
Steve Speicher | IBM Rational Software | (919) 254-0645
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