[OASIS Issue Tracker] (OSLCCORE-6) How does POST to an LDPC that supports multiple creationTypes indicate which resource to create?

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

    [ https://issues.oasis-open.org/browse/OSLCCORE-6?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=59504#comment-59504 ] 

James Amsden commented on OSLCCORE-6:
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There are two separate issues above. I'll try to clarify them separately:

1. Use of creationType

OSLC Core 3.0 Discovery specifies that the response to a HEAD, GET or OPTIONS request on an LDPC can return multiple Link headers with rel="http://open-services.net/ns/core#creationType"; in to indicate what resource RDF types can be created in that container.

The question is how clients should use this discovered information. Should a link header with rel="http://open-services.net/ns/core#creationType"; be included on a POST to that container to create a resource of that type, or is it expected that the entity request body on the POST would indicate the RDF type that should be created. i.e., do we expect servers to do anything with creationType headers on POST, or only return them for discovery?

2. constrainedBy association with creationType

OSLC Core 3.0 Discovery also specifies that the response to a HEAD, GET or OPTIONS request on an LDPC can return multiple Link headers with rel="http://www.w3.org/ns/ldp#constrainedBy"; to define constraints on the created resource. The issue is that if there are multiple types supported by the LDPC, then there may be different constraints on each type, and there needs to be some way of indicating which constraint goes with which type. I propose that the Link header with rel="http://www.w3.org/ns/ldp#constrainedBy"; should allow an anchor parameter to indicate the RDF type that is being constrained.


> How does POST to an LDPC that supports multiple creationTypes indicate which resource to create?
> ------------------------------------------------------------------------------------------------
>
>                 Key: OSLCCORE-6
>                 URL: https://issues.oasis-open.org/browse/OSLCCORE-6
>             Project: OASIS OSLC Lifecycle Integration Core (OSLC Core) TC
>          Issue Type: Task
>            Reporter: James Amsden
>            Assignee: James Amsden
>
> An OPTIONS request on an LDPC could return multiple Link: headers with rel="http://open-services.net/ns/core#creationType"; indicating the container can support multiple resource types. The Accept-Post header indicates the entity request body format, but does not specify the resource type expressed by that content. RDF resources could specify their type directly in an assertion, but this is not available for LDP-NR (Non-RDF) sources. 
> Section A.1.2 creationType seems to indicate that this could be used on a Link-relation rel value for POST, but this should be explicitly specified and have an example.
> A related issue is that an HTTP OPTIONS request on an LDPC can also return multiple Link: headers with rel="http://www.w3.org/ns/ldp#constrainedBy";. A POST or PUT to create or update a resource can use return this header when the request fails because of violation of the constraint. But there is currently no way to associate multiple creationType and constrainedBy link relations for an LDPC. The constraindBy link may need to include a context IRI (anchor parameter) to identify the resource type that is being constrained.



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