[OASIS Issue Tracker] (OSLCCORE-140) OSLC Core 3.0 Discovery does not describe the results of GET on a QueryCapability queryBase URL.

[OASIS Issues Tracker <workgroup_mailer@lists.oasis-open.org>]

     [ https://issues.oasis-open.org/browse/OSLCCORE-140?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

David Honey updated OSLCCORE-140:
---------------------------------

    Description: 
OSLC Core 3.0 Discovery defines QueryCapability and oslc:queryBase: The base URI to use for queries. Queries are invoked via HTTP GET on a query URI formed by appending a key=value pair to the base URI, as described in Query Capabilities section. But there is no Query Capabilities section in the Discovery document that describes what the results of such a GET would be, or addresses the OSLC Core 2.0 use of rdfs:member vs. ldp:contains. 

https://web.archive.org/web/20151031160403/http://open-services.net/bin/view/Main/OSLCCoreSpecRDFXMLExamples#Specifying_the_shape_of_a_query provides examples that use rdfs:member. However, that documernt does not appear to be referenced by the specification.

The use of lpd:contains is preferable because it is consistent with other LDPCs, some of which are, in essence, query-based containers without support for oslc.where. However, rdfs:member appears to the current usage, albeit not described in the OSLC Query 2.0 specification itself.

  was:OSLC Core 3.0 Discovery defines QueryCapability and oslc:queryBase: The base URI to use for queries. Queries are invoked via HTTP GET on a query URI formed by appending a key=value pair to the base URI, as described in Query Capabilities section. But there is no Query Capabilities section in the Discovery document that describes what the results of such a GET would be, or addresses the OSLC Core 2.0 use of rdfs:member vs. ldp:member. Since ldp:member is a subproperty of rdfs:member, OSLC Core 2.0 Query Capability's use of rdfs:member to list the members of a GET on a queryBase URL is compatible with the queryBase being an LDPC. However, this needs to be documented in the OSLC Core 3.0 Discovery specification and referenced in the updated OSLC Core 3.0 Query Capability specification.

       Proposal: 
We can satsify both backwards compatibility and LDPC compatibility by having the standard say that implementations SHOULD return an LDPC that includes both ldp:contains (as required by https://www.w3.org/TR/ldp/#ldpc) and rdfs:member. One way of having both is to use an ldp:DirectContainer. For example, consider a queryBase URI of http://example.com/query. A GET with some oslc.where query expression might have returned the following in an OSLC Query 2.0 implementation (omitting namespace prefixes for brevity):

<http://example.com/query>
    rdfs:member <http://example.com/resource/1>,
        <http://example.com/resource/2>,
        <http://example.com/resource/3>;

A response might be:

<http://example.com/query>
    a ldp:DirectContainer;
    ldp:membershipResource <http://example.com/query>;
    ldp:hasMemberRelation rdfs:member;
    ldp:contains <http://example.com/resource/1>,
        <http://example.com/resource/2>,
        <http://example.com/resource/3>;
    rdfs:member <http://example.com/resource/1>,
        <http://example.com/resource/2>,
        <http://example.com/resource/3>;

Additionally, the response should contain the following header:
Link: <http://www.w3.org/ns/ldp#DirectContainer>; rel="type",
      <http://www.w3.org/ns/ldp#Resource>; rel="type"



> OSLC Core 3.0 Discovery does not describe the results of GET on a QueryCapability queryBase URL.
> ------------------------------------------------------------------------------------------------
>
>                 Key: OSLCCORE-140
>                 URL: https://issues.oasis-open.org/browse/OSLCCORE-140
>             Project: OASIS OSLC Lifecycle Integration Core (OSLC Core) TC
>          Issue Type: Bug
>          Components: Core, Query
>            Reporter: James Amsden
>            Assignee: James Amsden
>
> OSLC Core 3.0 Discovery defines QueryCapability and oslc:queryBase: The base URI to use for queries. Queries are invoked via HTTP GET on a query URI formed by appending a key=value pair to the base URI, as described in Query Capabilities section. But there is no Query Capabilities section in the Discovery document that describes what the results of such a GET would be, or addresses the OSLC Core 2.0 use of rdfs:member vs. ldp:contains. 
> https://web.archive.org/web/20151031160403/http://open-services.net/bin/view/Main/OSLCCoreSpecRDFXMLExamples#Specifying_the_shape_of_a_query provides examples that use rdfs:member. However, that documernt does not appear to be referenced by the specification.
> The use of lpd:contains is preferable because it is consistent with other LDPCs, some of which are, in essence, query-based containers without support for oslc.where. However, rdfs:member appears to the current usage, albeit not described in the OSLC Query 2.0 specification itself.



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