Re: Call for Consensus: IRI resolution tests

On 25/10/15 16:14, Gregg Kellogg wrote:
> On Oct 25, 2015, at 8:48 AM, Andy Seaborne <andy@apache.org
> <mailto: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).

Being silent to me means the RFCs apply.  So we have two readings - we 
should have tests that do not choose one reading over another as we are 
not in the role of changing or interpreting the specs.

The RFCs say that ".." and "." are intended for relative URIs only.  RDF 
Concepts says they are "best avoided".

I think it is a bug in RFC 3986 and called out in 3987 as "situation not 
intended to happen".

 Andy

[*] A fix is merging the base and relative URI needs to treat "/.." as 
"/../" either by minimal normalization or in rule the merge rule. 
Otherwise various inconsistencies appear.


>
> 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?

"""
5.3 Resolving URIs

RDF/XML supports XML Base [XML-BASE] which defines a ·base-uri· accessor 
for each ·root event· and ·element event·. Relative URI references are 
resolved into RDF URI references according to the algorithm specified in 
XML Base [XML-BASE] (and RFC 2396).
"""
i.e. it says "use the algorithm".
>
> Gregg
>
>>> Best,
>>>
>>> Ruben
>>>
>>
>>

Received on Sunday, 25 October 2015 19:03:15 UTC