#53 R0886 uses different URI/IRI standard

[Maximilian Pilz]

Comment

It uses RFC 3986, but it should be RFC 2396 or RFC 3987.

Rationale / Proposed change

http://www.w3.org/TR/xmlschema-2/#anyURI references RFC 2396 instead of RFC 3986.
http://www.w3.org/TR/xmlschema11-2/#anyURI references RFC 3987 instead of RFC 3986.

[David]

It looks like the newer RFC does only impose restrictions; 3986 should be backwards compatible such that a 2396 parser can always parse 3986 URIs. Requirement has been relaxed to SHOULD.

[Maximilian Pilz]

I do not see this parser statement being true, for example "http:" is valid according to RFC 3986 and can be parsed by RFC 3986 parsers, but it is not allowed in RFC 2396 and thus may be rejected by an RFC 2396 parser.

This is also stated in RFC 3986:

"The ABNF has been corrected to allow the path component to be empty.
This also allows an absolute-URI to consist of nothing after the
"scheme:", as is present in practice with the "dav:" namespace
[RFC2518] and with the "about:" scheme used internally by many WWW
browser implementations."

Though your argumentation is wrong, it really is a matter of the corresponding XML schema being used or not, because it enforces RFC 2396 and thus would eliminate the possibility of such URI.

Then the question arrises, if those URIs that are valid for both are enough for the use case and if different segment names are a problem for interoperability.

[Björn Andersen]

Different segments names could lead to different parsing results!
Is this a potential problem?

[Maximilian Pilz]

Yes, it is a potential problem.

[David]

We shouldn't rely on outdated RFCs. For this reason, keep using RFC 3986 and fix the URI standard reference in BICEPS, see [ieee11073-10207:#209]

[Maximilian Pilz]

Could be fixed by changing the XML Schema links to link to the XML Schema version 1.1 and use RFC 3987.

https://sourceforge.net/p/opensdc/ieee11073-10207/246/
https://sourceforge.net/p/opensdc/ieee11073-20701/47/

[Björn Andersen]

Course of action:
1. Require XML Schema version 1.1 with 1.1-based datatypes in BICEPS, see [ieee11073-10207:#246].
2. Require XML Schema version 1.1 with 1.1-based datatypes in SDC, see [ieee11073-20701:#47].
3. Require RFC 3986 in BPKP, because every 3986 URI is (by definition) also a valid 3987 IRI. The advantage of using URIs rather that IRIs in SDC would be the reduced handling complexity for SDC participants, see [ieee11073-10207:#209].

[Björn Andersen]

@d-gregorczyk argues against this solution here: https://sourceforge.net/p/opensdc/ieee11073-20701/47/#81c7

If we do not want to require XML Schema 1.1, we may need to introduce a dirty fix like this:

An SDC Participant SHALL limit values of pm:InstanceIdentifier/@Root to those matching the form scheme ":" hier-part as defined in [RFC 3986] Clause 3 and scheme ":" hier_part as defined in [RFC 2396] Clause 3 except for "biceps.uri.unk" and "sdc.ctxt.loc.detail".

[Björn Andersen]

Accepted as proposed on 2022/03/10.