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

From: Richard Cyganiak <richard@cyganiak.de>
Date: Thu, 27 Mar 2014 11:35:31 +0000
Cc: "public-ldp@w3.org" <public-ldp@w3.org>
Message-Id: <174E3C09-9B24-4213-A59F-DFE50D744240@cyganiak.de>
To: Reto GmŁr <reto@apache.org>, Henry Story <henry.story@bblfish.net>
Reto,

On 26 Mar 2014, at 09:29, Reto GmŁr <reto@apache.org> wrote:
>> It is clear that the usage of relative URIs is correct here and in the spirit of the web.
> 
> Clearly not. If the RDF Data Model would support relative URIs then it would be an acceptable solution (Antoine's still being more elegant, imho). But as RDF has no relative URIs this is just an unnecessary hack.

You are absolutely right that the RDF Data Model doesn't support relative IRIs.

But why is this? Is it by design? I think the reason is historic: the use cases didnít seem sufficiently compelling at that time.

Back then, RDF/XML was the only syntax intended for deployment, so the line between whatís syntax and whatís model could be drawn more or less anywhere. The WG tried to keep the model as simple as possible, and perhaps ended up making it too simple.

Today, we have an entire zoo of syntaxes, and many of them share certain features that are not in the model, especially support for relative IRIs and prefix mappings. The fact that these features are not in the data model leads to multiple problems, including subtle interoperability failures, poor support in library APIs, varying behaviour across implementations, and poor user understanding. Real instances of these problems have been brought up by you and Pierre-Antoine in this discussion. If the features were normatively defined in the model, then interoperability and support would likely be better and more consistent.

Perhaps the latest RDF WG could have done something to improve this situation, but it didnít, for complex reasons. As a member of that WG and one of the editors of the relevant document, I will accept some of the blame for this.

I think Henry makes a good case that the use of relative IRIs is the Right Thing here. Itís practical, it has precedent with the way HTML works, itís webby, and itís supported by the relevant RFCs.

Given all this, it appears to me that using relative IRIs to good effect in LDP is a step in the right direction.

Best,
Richard
Received on Thursday, 27 March 2014 11:36:03 UTC

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