Re: [Uri-review] ACTION-103 Follow up on the about: scheme Registration

<454C3572-0594-4D66-9472-968A0E78809D@josephholsten.com>

Current votes: None.


On Feb 23, 2010, at 3:27 AM, Julian Reschke wrote:

> On 23.02.2010 10:08, Joseph Holsten wrote:
>> On Feb 22, 2010, at 8:26 AM, Julian Reschke wrote:
>>> 1)
>>>=20
>>> "7. Relative "about" URIs
>>>=20
>>>   As "about" URIs do not use a hierarchical path, relative "about" =
URIs
>>>   are not permitted."
>>>=20
>>> I think this is misleading.
>>>=20
>>> A relative reference, as defined =
in<http://greenbytes.de/tech/webdav/rfc3986.html#rfc.section.4.2>, does =
not contain a URI scheme (by definition). So it's meaningless to talk =
about the scheme of a reference.
>>>=20
>>> In doubt, just drop the paragraph.
>>=20
>> It's meaningless, but there are a few issues. First, as a stupid =
implementor writing a URI parser and handler, I'm used to having to deal =
with relative URIs. Obviously, I'm going to be confused about the right =
thing to do is. I want to tell these people, "Don't worry, you don't =
have to deal with relative about URIs, they don't exist."
>=20
> Well, there aren't relative URIs. They are called "relative =
references". They do not have a scheme.
>=20
> So the question needs to be rephrased as: "what does happen when I =
resolve a relative reference against an "about" URI"? The answer is the =
same for all URIs (because generic URI processors need to be able to do =
this regardless the scheme), and the answer is in RFC 3986, Section 5 =
(<http://greenbytes.de/tech/webdav/rfc3986.html#rfc.section.5>).

I learn something new every day. Looks like I just swiped this from RFC =
2397.

Trouble is, I'm seriously confused as to whether about URIs can or can't =
have relative references. So far as I can tell, RFC 3986 =A74.4 says the =
handling of short same-document references (e.g. #SectionOne) is =
formally defined in =A75.2.2. But =A7D.2 says:

"The determination of whether a URI reference is a same-document =
reference has been decoupled from the URI parser, simplifying the URI =
processing interface within applications in a way consistent with the =
internal architecture of deployed URI processing implementations. The =
determination is now based on comparison to the base URI after =
transforming a reference to absolute form, rather than on the format of =
the reference itself. This change may result in more references being =
considered "same-document" under this specification than there would be =
under the rules given in RFC 2396, especially when normalization is used =
to reduce aliases. However, it does not change the status of existing =
same-document references."

Which makes me think I'm wrong. Surely there is a way for =
non-hierarchical URIs to handle same-document references. Obviously the =
recomposition function in =A75.3 only generates hierarchical URIs. I =
want to say this is a bug in RFC 3986, but that seems hard to believe.

I'm beginning to think the reason I added that line was to remind myself =
that this is hard to verify.

Links:
RFC 2397. The "data" URL scheme, http://tools.ietf.org/html/rfc2397
RFC 3986 =A74.4. Same-Document Reference, =
http://greenbytes.de/tech/webdav/rfc3986.html#rfc.section.4.4
RFC 3986 =A75.3. Component Recomposition, =
http://greenbytes.de/tech/webdav/rfc3986.html#rfc.section.5.3
RFC 3986 =A7D.2. Modifications. =
http://greenbytes.de/tech/webdav/rfc3986.html#rfc.section.D.2
--
j=