Re: [Netconf] Unable to filter strings with leading whitespace

----- Original Message -----
From: "Balazs Lengyel" <balazs.lengyel@ericsson.com>
To: <netconf@ietf.org>
Cc: "Peter Labraaten" <peter.labraaten@ericsson.com>
Sent: Friday, February 20, 2015 1:55 PM

> Hello,
> I assume that " hello" with the leading space is a perfectly OK value
in
> Netconf/YANG for a string leaf. I also think that the " hello" string
is
> not the same as the "hello" string without the space.
> However https://tools.ietf.org/html/rfc6241#section-6.2.5 part of the
> Netconf RFC says about filtering
>
> "Leading and trailing whitespace characters are ignored, but any
>        whitespace characters within a block of text characters are not
>        ignored or modified."
>
> IMHO this is an error for YANG string leafs. It is perfectly OK to
> convert an integer "  1" into "1" but converting the string " hello"
> into "hello" is changing its content. So there should be an errata
> stating that for string type content all white space content is
> considered during filtering.
>
> Agree? If you do not agree, how am I supposed to filter for " hello"
> instead of "hello"?

You can't!  I think that the Netconf RFC is very clear.  YANG does allow
spaces to be significant or not, depending on the quoting (RFC6020
s6.1.3) but Netconf, as you point out, does not.

Nor is this an erratum, which would imply that the RFC wrongly (or
unclearly) states the consensus of the WG.

The text you cite first appears in
  draft-ietf-netconf-prot-06
in April 2005, following an e-mail from Andy  at
http://www.ietf.org/mail-archive/web/netconf/current/msg00414.html

The earlier text also came from Andy
http://www.ietf.org/mail-archive/web/netconf/current/msg00004.html

There was a lengthy discourse on subpath filtering between the two but
that was about whether to have home-grown filtering, a subset of XPath
or full XPath or some combination thereof.

Tom Petch

> regards Balazs
>
>
> --
> Balazs Lengyel                       Ericsson Hungary Ltd.
> Senior Specialist
> ECN: 831 7320                        Tel: +36-1-437-7320
> Mobile: +36-70-330-7909              email:
Balazs.Lengyel@ericsson.com
>
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Re: [Netconf] Unable to filter strings with leading whitespace - errata on Netconf RFC?