[OASIS Issue Tracker] (OSLCCORE-44) oslc:instanceShape should explicitly allow multiple values

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    [ https://issues.oasis-open.org/browse/OSLCCORE-44?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=61156#comment-61156 ] 

Nick Crossley commented on OSLCCORE-44:
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It is not clear to me what the semantics of multiple instance shapes would be. There have been other proposals for saying that one shape extends another, via a new property on a shape, and there has been other work on dynamic merging of shapes for query builders. I do not believe we are ready to introduce multiple instance shapes as another way to address variant shapes.

As for the asymmetry in the cardinalities of resource shapes on creation factories vs. query capabilities, this was in fact deliberate. Multiple create shapes are allowed, to handle multiple possible resource types being POSTable to the same factory. On the other hand, a single query capability shape defines the shape of the single query base resource itself, which might in turn have references to resources of various types, using the valueShape property for property definitions in the outer shape. However, I do note an issue there - a property definition may have multiple values for oslc:range (which is presumably intended to indicate a union of possible types, though it doesn't say so), and it may have multiple oslc:valueType values (the semantics of which are again undefined), but it may have only a single valueShape! Logically, multiple valueShapes should be allowed, though it would be impossible to correlate the value shapes with the value types and oslc:range values other than by assumptions based on the rdf:type of the linked resources.

> oslc:instanceShape should explicitly allow multiple values
> ----------------------------------------------------------
>
>                 Key: OSLCCORE-44
>                 URL: https://issues.oasis-open.org/browse/OSLCCORE-44
>             Project: OASIS OSLC Lifecycle Integration Core (OSLC Core) TC
>          Issue Type: Bug
>            Reporter: Martin Pain
>            Assignee: James Amsden
>
> With a quick look on both Core 2.0 and the W3C member submission for Resource Shapes, it looks like neither mention whether a client can expect zero-or-one or zero-or-many instanceShape links from a resource.
> I would expect zero-or-many. As I can't see any problem with an instance having the properties from multiple shapes. This would help with the question about vendor-specific shapes raised on OSLCCORE-25 - as then the resources can include a link to both the vendor-specific shape and the OSLC TC-minted-URI for the a shape as defined in the spec.
> In v3.0 I think we should clarify this to state that a resource can specify zero or more instance shapes. (If we don't already & I missed it).



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