Re: Call for Consensus: IRI resolution tests

On Oct 25, 2015, at 8:48 AM, Andy Seaborne <andy@apache.org> wrote:
> 
>> On 25/10/15 12:01, Ruben Verborgh wrote:
>> Dear Andy,
>> 
>>> The tests make an additional assumption that absolute URIs are not normalized.  This is not covered by the Turtle spec one way or another (nor should it be).  Both normalizing and not normalizing are possible.
>> 
>> I disagree here—there Turtle spec should cover this.
> 
> "should" or "does"? Are you arguing for a change to Turtle?
> 
> If it's a change, then -1 to these tests.
> 
> One way is to avoid the area that is a problem for 3986 and change the tests to use the "/../" from the "/.." form.  As you yourself noted, normalization is assumed by RFC3986/5.2. Or follow RFC 3987 and don't have absolute URIs with them in.
> 
>> Otherwise, two identical Turtle documents can result in different sets of triples.
> 
> ... in the one case where the base URI ends in "/.." which isn't good practice; RFC 3987/5.3.2.4 even says it is not intended usage.
> 
>> I think it's clear that absolute URIS should not be touched,
>> and that the spec also says this.
> 
> The spec being Turtle?
> 
> Please quote text where it says that about @base.

The key for me was this sentence from the IRIs section:

> Relative IRIs like <#green-goblin> are resolved relative to the current base IRI.

It says that _relative_ IRIs are resolved, but is silent on absolute IRIs. Thus, if the value of @base is an absolute IRI it is not changed at all, and used as is when resolving other relative IRIs. (Note, my implementation did this previously, but I was convinced this was an error; always resolving an IRI against the current base is supported in RFC3982, but not called for from our specs. If it were, it would arguably be more consistent).

Looking at other specs, I think the same is true for JSON-LD, RDFa and RDF/XML.

>    Andy
> 
> (RDF/XML is different on relative URIs)

Why do you say this? Can you site something from the spec?

Gregg

>> Best,
>> 
>> Ruben
> 
>