W3C home > Mailing lists > Public > public-ldp@w3.org > March 2014

Re: Practical issues arising from the "null relative URIs"-hack

From: Richard Cyganiak <richard@cyganiak.de>
Date: Thu, 27 Mar 2014 13:38:39 +0000
Cc: Henry Story <henry.story@bblfish.net>, "public-ldp@w3.org" <public-ldp@w3.org>
Message-Id: <30E45287-43B3-45A2-A6B0-AC828FF3A8CC@cyganiak.de>
To: Reto Gmr <reto@wymiwyg.com>
Hi Reto,

On 27 Mar 2014, at 13:05, Reto Gmr <reto@wymiwyg.com> wrote:
> Of course if you want the prefixes to remain the same RDF isn't the right level of abstraction to work on.

Well, then what *is* the right level of abstraction?

Users who convert an RDF/XML file to Turtle usually expect that prefix mappings and relative IRIs are retained. Not all tools do this, and this is a common source of confusion and complaints.

So the syntax level is not right (information should be carried across syntaxes), and neither is the RDF graph level (the information is not part of the RDF graph model).

My view is that this missing level should be standardised. And if it were standardised, then that extended model would be a reasonable candidate for the payload of LDP messages.

Whether the required definitions happen in the RDF specs, in the LDP spec, or somewhere else, doesnt really matter for this argument.

>> I think Henry makes a good case that the use of relative IRIs is the Right Thing here. Its practical, it has precedent with the way HTML works, its webby, and its supported by the relevant RFCs.
> 
> Ok, let's look into this:
> - "practical": it requires hack on the client (throwaway URI to serialize against) and prevents framework to be effectively used on the server side. As for expressiveness it allows less flexibility (creating multiple resources in one post) as Antoine's proposal

It works just fine, without hacks, if client and server use RDF libraries that support relative IRIs.

> - "it has precedent": I don't know of any protocol which requires the sender to send URIs that are relative to something that isn't defined yet. So I don't know where the precedent is.

There are protocols (WebDAV, APP) where messages with relative IRIs can be POSTed and it works just as expected.

> - "supported by the relevant RFCs": The RFC says the sender is responsible that the base URI can be established, this seems quite different from "the receiver defines a base URI" to me.And I haven't got an answer to  http://lists.w3.org/Archives/Public/public-ldp/2014Mar/0033.html yet.

If the protocol implemented by the server asserts that the server will choose an appropriate base IRI, then a client has met its responsibility by using that protocol.

>> Given all this, it appears to me that using relative IRIs to good effect in LDP is a step in the right direction.
> 
> Well the goal of LDP is not to establish faits accomplis to push the RDF specification to adopt new features but in my understanding to apply the existing standards where possible. As for this use case there are alternatives that do not go beyond the current standard and they do not provide any disadvantage (except if you need the dirt) I don't think we should go beyond the existing standard.

As you have seen in this thread, one can argue in either direction by pointing to existing standards.

It comes down to a question whether you prefer to do the Right Thing vis-a-vis RDF Concepts or vis-a-vis RFCs 2616 and 3986.

Best,
Richard
Received on Thursday, 27 March 2014 13:39:06 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 16:16:37 UTC