Re: [netmod] [Technical Errata Reported] RFC7950 (5157)

Jan Lindblad <janl@tail-f.com> Tue, 24 October 2017 10:41 UTC

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From: Jan Lindblad <janl@tail-f.com>
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Date: Tue, 24 Oct 2017 12:41:16 +0200
Cc: Andy Bierman <andy@yumaworks.com>, Vladimir Vassilev <vladimir@transpacket.com>, "netmod@ietf.org" <netmod@ietf.org>
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To: Robert Wilton <rwilton@cisco.com>
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Subject: Re: [netmod] [Technical Errata Reported] RFC7950 (5157)
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Rob,

>> The XPath mixed-quotes problem is well-known, and the suggested
>> solution seems to be use the "concat" function
>> 
>>    /foo/bar[name=concat("It's a", ' "valid" string')]
>> 
>> Not very user friendly, is it?
> 
> I suspect that this is unlikely to be popular, but I think that it would be nice if there was a plan to move away from XPath, and define a YANG specific equivalent instead.  Broadly it could follow the same format as XPath but be defined against a YANG data tree, and bind to YANG's types.  We could get rid of the bits of XPath that aren't really helpful or meaningful for YANG, and add in some new functionality/fixes that are helpful to solve the YANG specific problems related to path expressions.

The idea has some merit, and I understand the background for this sentiment. Trying not to be on either side at this point, I would just like to point out that this would mean a considerable amount of work. Both for the WG to define this language, and later, for implementors to implement it.

/jan