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RE: Multiple representations of the same resource without content negotiation

From: <Armin.Haller@csiro.au>
Date: Fri, 28 Sep 2012 19:03:52 +1000
To: <Erik.Wilde@emc.com>, <public-ldp-wg@w3.org>
Message-ID: <378F8A27C40D3741AC0445CC2A5C50E0F004126E97@EXNSW-MBX05.nexus.csiro.au>
Hi Erik,

Thanks for the response, see comments below.

> >Of course content negotiation can be used to retrieve the different
> >representations of the same object. However, how does the user know what
> >representations do exist about this object?
> 
> ideally, you would expose that RESTfully through link relations, and many
> RESTful data formats have ways of exposing "alternate" links to resources
> ("alternate" is one of the registered link relationships in the IANA link
> registry
> http://www.iana.org/assignments/link-relations/link-relations.xml). so if
> you GET a resource, links can be exposed in HTTP, allowing clients to
> understand the available set of resources.
> 
> additionally, there's a "describedby" link relation (defined in POWDER),
> and there's "describes" (draft
> http://tools.ietf.org/html/draft-wilde-describes-link), which allow to
> represent the relationships between described resources and description
> resources independent of any specific resource representation. this is
> important, because requiring clients to understand a specific format so
> that they can decide how to find a format that they support and thus can
> request would be a bit counterproductive. so my recommendation would be to
> not encode fundamental discoverability issues like this in a specific
> format, and instead rely on HTTP and link relations, so that you support a
> bigger set of clients.

Ok, that does make sense to me and I was not aware of POWDER. It does solve the problem of referring the user to other resource representations, but do we really want to only model this on the REST layer and not reference it from the semantic layer? Should we not maintain the list of available resource representations also in the RDF model and keep the two in sync/link them? A user can then figure out that there are other resource representations on the REST layer as well as on the semantic layer and the LDP could support both ways.
Received on Friday, 28 September 2012 09:04:29 UTC

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