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Fw: [oslc-core] Proposal to remove Link header option from Resource Preview spec

From: John Arwe <johnarwe@us.ibm.com>
Date: Tue, 2 Sep 2014 11:48:44 -0400
To: "public-ldp-wg@w3.org Working Group" <public-ldp-wg@w3.org>
Message-ID: <OF688D05C9.659846F9-ON85257D47.0055519B-85257D47.0056DEBD@us.ibm.com>
The >-quoted text is from a Sam Padgett offline email.  He's working on 
the Eclipse Lyo reference implementation and test suite.

> Should we add mention the Link header context in the LDP spec? For 
> instance, this requirement? It seems like describedby should have an
> anchor parameter here.
> http://www.w3.org/TR/ldp/#ldpc-post-createbinlinkmetahdr
> Upon successful creation of an LDP-NR (HTTP status code of 
> 201-Created and URI indicated by Location response header), LDP 
> servers MAY create an associated LDP-RS to contain data about the 
> newly created LDP-NR. If a LDP server creates this associated LDP-RS
> it MUST indicate its location on the HTTP response using the HTTP 
> Link response header with link relation describedby and href to be 
> the URI of the associated LDP-RS resource [RFC5988]. 

Short answer, yes; I think we should clarify that the context URI for the 
Link header is *not* the default, so anchor= is required.
I don't think that's any change of intent (all the existing implementation 
report suppliers got it right, assuming the tests cover it);  anyone in 
the WG discussions I think would say that our intent (expressed as a 
pseudo-RDF-triple) was

newly-created-LDP-NR   describedby   newly-created-LDP-RS

Since the effective request URI in this case was an existing LDPC, not the 
newly-created-LDP-NR, the default Link context URI (LDPC's URI) is not our 

As a more concrete example, consider the following:

>     POST /bugs HTTP/1.1
>      HOST: rtc9-foo.tivlab.ibm.com 
>  ... 
>     HTTP/1.1 201 Created
>      Location: http://rtc-master.ibm.com/bugs/478
>      Link: <http://example-previews.com/bugs/478?compact>; rel="
describedby"; anchor="http://rtc-master.ibm.com/bugs/478",
>            <http://www.w3.org/ns/ldp#Resource>; rel="type"

*With* anchor= (context URI) present, this expresses our intent: "bugs/478 
describedby ...?compact"
Remove anchor=, and it says instead "/bugs  describedby  ...?compact".

Best Regards, John

Voice US 845-435-9470  BluePages
Cloud and Smarter Infrastructure OSLC Lead
Received on Tuesday, 2 September 2014 15:49:18 UTC

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