[oslc-core] Comments on OSLC Core Specification Version 2.0 - DRAFT

Dave snoopdave at gmail.com
Mon Jun 14 15:00:55 EDT 2010


Hi Arthur,

Thanks for taking the time to do a detailed review. This is very
helpful. I have added each of your comments to the issues page and I
will work through them and responding there for most of the issues.

   http://open-services.net/bin/view/Main/OslcCoreV1Issues

- Dave


On Mon, Jun 14, 2010 at 2:31 PM, Arthur Ryman <ryman at ca.ibm.com> wrote:
> I carefully read the entire spec again, this time translating it into OWL
> as a check on its overall consistency. I corrected some obvious typos.
> Here are the issues I found below. I also have some comments on how the
> Core spec relates to OWL, which I'll send in a separate note.
>
> 1. Resource value-types. There is a technical error in the description of
> Local Inline Resource and the subsequent examples. The spec incorrectly
> uses rdf:ID to refer to local resources. Recall that we introduced the
> term "local resource" to be a synonym for "blank node" because we did not
> want to depend on RDF terminology. I think we should look at this decision
> again since the new terms and descriptions we are introducing may be
> adding to the confusion instead of simplifying the specification.
>
> The correction is to use rdf:nodeID whenever referring to a blank node
> within an RDF/XML document. The rules are described in [1].
>
> rdf:ID is also very useful, but is not used for blank nodes. It is used to
> define URI references that are relative to the XML base of the RDF/XML
> document. [2] rdf:ID defines a unique fragment identifier within the
> document, which is then appended to the base URI + "#" to for a URI
> reference.These URI references are global, i.e. their values have meaning
> outside the document. They are useful for identifying resources within an
> RDF/XML document.
>
> We introduced the concepts of local and inline resources to put
> constraints on the format of documents so that they would be easier to
> parse. However, we are using most of RDF/XML anyway, so maybe we should
> simply allow RDF/XML and use the correct RDF terms? A quick Google search
> shows that there are RDF parsers for all major languages.
>
> 2. dc:title and dc:description
>
> First, we are using the dcterms namespace, so our documentation should use
> the prefix dcterms: which is the normal convention. dc: is conventionally
> used for the DC elements namespace.
>
> Second, we had a long email discussion on using rich text for these
> properties, specifically XHTML <span> and <div> content, and this is
> recommended in Appendix A. [3] This means the datatype should be
> rdf:XMLLiteral. However, the Core uses string for these on its own
> resources. Shouldn't we follow our own recommendations?
>
> 3. Resource: Respsonse Information - the value of oslc:nextPage should be
> a resource, not a string.
>
> 4. In Conceptual Model diagram oslc:QueryCapability should be
> oslc:queryCapability - the convention is that property names start with
> lowercase letter, and class and individual names start with uppercase
> letter.
>
> 5. Namespace Definition versus Prefix Definition - I think these are the
> same thing, but both terms are used in the spec. We should use
> PrefixDefinition.
>
> 6. Resource: Service Provider - the spec says that namespace definitions,
> aka predefined prefixes, can be used in JSON respresentations, We should
> only use predefined prefixes on URLs to keep them short and readable. We
> should NOT use predefined prefixes in documents. Documents should be
> self-contained and define any prefixes they use.
>
> 7. Resource: Creation Factory - the spec uses both oslc:Factory and
> oslc:CreationFactory. These are the same. We should only use
> oslc:CreationFactory.
>
> 8. Resource: Error
> - the datatype of oslc:statusCode is Decimal. I suggest that String is
> more appropriate since a code is usually an arbitrary sequence of
> characters, not necessarily a decimal number.
> - the (misspelled) property oslc:exendedMessage should be
> oslc:extendedError since it refers to an ExtendedError resource
> - the text refers to the resource type oslc:ExtendedMessage but that
> should be oslc:ExtendedError
>
> 9. Resource: Extended Error
> - the properly oslc:url should be renamed to the more descriptive term
> oslc:moreInfo since it refers to a document that contains more information
> - the property oslc:rel has datatype Resource which is inconsistent with
> the text which defines a string value 'alternate'. The datatype should
> therefore be String
> - the properties oslc:highWidth and oslc:hintHeight have datatype Decimal,
> but this is inconsistent with their use elsewhere, where it is String in
> order to allow CSS window size units. Use String here too.
>
> 10. JSON Representations
>  - the text refers to QNames but should refer to Prefixed Name. A QName
> represents a pair consisting of a namespace URI and a local name. A
> Prefixed name represents a URI ref.
> - the property rdf:id is used but this should be rdf:nodeID
>
> [1] http://www.w3.org/TR/REC-rdf-syntax/#section-Syntax-blank-nodes
> [2] http://www.w3.org/TR/REC-rdf-syntax/#section-Syntax-ID-xml-base
> [3]
> http://open-services.net/bin/view/Main/OSLCCoreSpecAppendixADRAFT?sortcol=table;up=#Dublin_Core_Properties
>
> 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
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