Re: Server behaviour on PUT

On Thu, May 16, 2013 at 10:21 AM, Raúl García Castro <rgarcia@fi.upm.es>wrote:

> Dear all,
>
> [[
> 4.4.1 If HTTP PUT is performed on an existing resource, LDPR servers MUST
> replace the entire persistent state of the identified resource with the
> entity representation in the body of the request.
> ]]
>
> Currently there are no restrictions on the representation of resources
> allowed by a server. Therefore, an LDPR representation submitted by a
> client may include properties that will be ignored by the server and
> properties that will not be ignored by the server. Besides, the LDPR
> representation provided by a server may include properties submitted by the
> client and properties not managed by the client (e.g., timestamp). Right
> now it may happen that all the properties in the client representation are
> ignored and the server representation includes only server managed
> properties (i.e., the specification does not restrict this).
>
> In summary, when a client updates a resource anything can happen. E.g.,
> the server may ignore every property stated by the client. However, the
> specification seems to indicate the contrary, that all the properties
> exposed for an LDPR can be freely updated by a client.
>
> While this can be the case for vanilla LDP servers, which don’t take into
> account the contents of resources, it does not hold for domain-dependent
> LDP servers that expose data for whom specific restrictions apply, i.e.,
> certain properties are not under the control of the client.
>
> At the same time, this MUST clause does not align with what is said in the
> next MAY clause on the same point, which asserts that LDP servers can
> ignore server managed properties.
>
> A collateral effect in terms of testing is that, since LDP servers are not
> forced a minimum behaviour on PUT, no data validation is possible (e.g., we
> can only check that a different ETag is returned on the updated resource).
>
> Proposal:
>
> Rewrite clause 4.4.1 making clear that only the part of the LDPR state
> that is under the control of the client will be updated with the contents
> of the representation, and that it is the responsibility of the LDP server
> to define which parts of the representation are under its control.
>
>
I think the 4.4.* sections cover this already, reading 4.4.3 and 4.4.4.  It
is hard to put everything into 4.4.1 itself.  I'd be interested to hear
others opinion or see what language in the following sections doesn't meet
this need.

- Steve


> Kind regards,
>
> --
>
> Dr. Raúl García Castro
> http://delicias.dia.fi.upm.es/**~rgarcia/<http://delicias.dia.fi.upm.es/~rgarcia/>
>
> Ontology Engineering Group
> Departamento de Inteligencia Artificial
> Universidad Politécnica de Madrid
> Campus de Montegancedo, s/n - Boadilla del Monte - 28660 Madrid
> Phone: +34 91 336 36 70 - Fax: +34 91 352 48 19
>
>


-- 
- Steve