Re: LDPR Interaction Model on Create

Hi all,

On 10/14/2014 11:06 AM, Steve Speicher wrote:
> Hi Nandana,
> 
> On Mon, Oct 13, 2014 at 9:59 AM, Nandana Mihindukulasooriya
> <nmihindu@fi.upm.es> wrote:
>> Hi John/SteveS,
>>
>> On Fri, Oct 10, 2014 at 5:50 PM, John Arwe <johnarwe@us.ibm.com> wrote:
>>>
>>> Moving this onto the right list for drafting a consensus response.
>>>
>>>> I also have a small comment that I've been meaning to send regarding the
>>>> interaction model.
>>>>
>>>> 5.2.3.4 states that "Clients use the same syntax, that is HTTP Link
>>>> headers, to specify the desired interaction model when creating a
>>>> resource as servers use to advertise it on responses."
>>>>
>>>> I noticed that in the primer, the POST request to an LDP-BC does not
>>>> contain a link header expressing the type of the resource to be created.
>>>> That also seems to be the behaviour of test suite. However, the POST
>>>> request to an LDP-DC *contains* the Link header Link:
>>>> <http://www.w3.org/ns/ldp#Resource>; rel="type", while *none* of the
>>>> examples in the LDP spec show a Link header being sent with POST
>>>> requests.
>>>
>>> THAT should be fixed, for sure.
>>> The only way a LDP client gets predictable behavior is by specifying the
>>> interaction model.
>>> That's what the examples should show, period... that which is
>>> interoperable.
>>
>>
>> I'm a bit confused regarding what is the consensus regarding including the
>> interaction model header and what to do in the primer examples on
>> POST/Create.
>>
>> In a previous email SteveS mentioned "I think requiring the header on create
>> was not intended and not desirable.  IF the header is present AND the server
>> can honor the request, then the client overrides whatever the server would
>> have done based on the content.  So I think that it makes complete sense for
>> LDP servers to determine the interaction model based on the content of the
>> creation request, with the Link header being part of that.". I thought it
>> was more biased towards not including the header in the primer examples.
> 
> Just stating my personal preference to "point people in the right
> direction" instead of "entirely open".  So I'd suggest we put
> something in BP (maybe primer) that says when client doesn't supply
> Link: rel="type" it is impl-specific, though they could dig into the
> content, find rdf:type to determine IM and send back Link: rel="type"
> indicate what it picked for the newly minted URI.
> 
>> But John's reply as well as Issue-91 suggests that we should include the
>> type Link relation header in the POST creation requests.
>>
>> So shall we include the interaction model header in all the POST creation
>> examples?
> 
> POST creation of LDPCs, yes.  POST creation of LDPRs, no.  I'm not
> sure what including type="LDPR" would mean when posting a LDPR to a
> LDPC, as it should not affect the already set interaction model of the
> LDPC.  Perhaps that is some extension to indicate on a per-request to
> a LDPC but feels a bit like it would violate what we have a MUST
> requirements on honoring client's requested interaction model on
> creation of the container (and would need to be expanded to other
> operations that affect containment and membership, like DELETE).

I thought the rel value would always be "type" (not "LDPR") when posting
an LDPR to an LDPC -- i.e. Link: <http://www.w3.org/ns/ldp#Resource>;
rel="type" .

-- Andrei

> 
> - Steve
> 
>>
>> Best Regards,
>> Nandana
>>
>>
>>
>>
>