Bogaert, Bart (Nokia - BE) je 12.5.2016 ob 11:28 napisal:
Juergen,
Thanks for the feedback.
With respect to functions available when using XPATH: XPATH 1.0 refers to a
Core Function Library. All the functions defined in there (Node set
functions, string functions, Boolean and number functions) are available in
a YANG XPATH context?
Yes. All functions defined in XPATH spec [1] are available. Usage of
some of them is discouraged, however. See Section 5.6.2 of usage
guidelines document [2].
[1] - https://www.w3.org/TR/1999/REC-xpath-19991116/#corelib
[2] -
https://tools.ietf.org/html/draft-ietf-netmod-rfc6087bis-06#section-5.6.2
Jernej
How wide-spread XPATH 2.0 and 3.0 is I also do not have an idea (I'm
currently "playing" with BaseX and there these versions are supported as far
as I know) but the fact that there are multiple versions of the standard can
cause confusion about what is "in" and what is "not in". So if, for
RFC6020bis, the supported set of functions is:
1. the Core Function library of XPATH 1.0
2. the added functions listed in RFC6020bis
We could conclude that the functionality is "confined". Maybe a statement
about full support of the Core Function Library of XPATH 1.0 in the RFC
could take away that ambiguity?
Best regards - Vriendelijke groeten,
Bart Bogaert
Broadband-Access System Architect Data
Contact number +32 3 2408310 (+32 477 673952)
NOKIA
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-----Original Message-----
From: EXT Juergen Schoenwaelder
[mailto:j.schoenwael...@jacobs-university.de]
Sent: 12 May 2016 10:57
To: Bogaert, Bart (Nokia - BE)
Cc: netmod@ietf.org
Subject: Re: [netmod] yang-next
On Thu, May 12, 2016 at 08:33:36AM +0000, Bogaert, Bart (Nokia - BE) wrote:
Hi,
Not sure whether this has been requested before but has it ever been
considered to support higher versions of XPATH in YANG? As far as I
remember only XPATH 1.0 is supported in YANG although the RFC mentions
adopting of XPATH 2.0 with respect to handling of unprefixed names.
RFC6020bis lists a set of functions that have been added and that are
available in an XPATH context. XPATH itself at this moment is at version
3.1. Some questions:
- are there any plans to follow the XPATH evolution in YANG?
So far, XPATH 2.0 has been considered too complex to require and there were
concerns of how widespread support there is for XPATH 2.0 (and
3.0 was never mentioned I think).
- to me at least it is not specifically clear what is and what is not
supported w.r.t. XPATH in YANG. Is there no clarification required in this
context?
Can you further detail what you find missing or unclear in
draft-ietf-netmod-rfc6020bis-12.txt regarding xpath? Simply search for
xpath, there is quite some text in various places.
Certain checks can't be expressed using an XPATH and require XQUERY (e.g.
when one need to follow a linked list in case of a lookup of a specific
node). Are there any plans to include support for XQUERY in YANG?
So far not.
Note that the goal so far has been to be somewhat conservative, that is, to
add features based on a good understanding which real-world problems are
being solved and ideally based on implementation and even better early
deployment experience. (A new feature that has been implemented and
successfully used as proprietary extensions is likely more important to
consider than something that exists as an idea on paper only).
/js
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