On Wed, Oct 10, 2018 at 6:59 PM, Reshad Rahman (rrahman) <[email protected]>
wrote:

> On 2018-10-10, 9:59 AM, "netmod on behalf of Martin Bjorklund" <
> [email protected] on behalf of [email protected]> wrote:
>
>     Ladislav Lhotka <[email protected]> wrote:
>     > Martin Bjorklund <[email protected]> writes:
>     >
>     > > Hi,
>     > >
>     > > While reviewing restconf-notif, I saw this example:
>     > >
>     > >    {
>     > >       "ietf-subscribed-notifications:input": {
>     > >          "stream": "NETCONF",
>     > >          "stream-xpath-filter": "/ds:foo/",
>     > >          "dscp": "10"
>     > >       }
>     > >    }
>     > >
>     > > Note the "stream-xpath-filter".  It has a prefix in the XPath
> string.
>     > > How are prefixes declared when JSON is used?
>     > >
>     > > The leaf "stream-xpath-filter" says:
>     > >
>     > >               o  The set of namespace declarations are those in
> scope on
>     > >                  the 'stream-xpath-filter' leaf element.
>     > >
>     > > (I think I provided that text...)
>     > >
>     > > This assumes that the encoding is XML, or at leas that the encoding
>     > > can somehow transfer namespace declarations.
>     >
>     > It can't. There are two options:
>     >
>     > 1. have different representations of this value in XML and JSON,
>     >    analogically to instance indentifiers (sec. 6.11 in RFC 7951).
>     >
>     > 2. use a module name rather than a prefix in XML, too.
>     >
>     > I would suggest #2.
> <RR> But that means making non-backwards compatible change to the XML
> representation?
>

Not really. It means NETMOD WG would be creating its own special variant of
XPath.


>     Hmm, so you mean change the leaf "stream-xpath-filter" to say:
>
>              o  The set of namespace declarations has one member for each
>                 YANG module supported by the server.  This member maps
>                 from the YANG module name to the YANG module namespace.
>
>                 This means that in the XPath expression, the module name
>                 serves as the prefix.
>
>     .... and then also give an example of this.
>
>     This is probably what we need to do in all places where yang:xpath1.0
>     is used, going forward.  Maybe even define a new type
>     yang:xpath1.0-2 (name?) with the set of namespace declarations
>     built-in.
>


We should avoid making off-the-shelf implementations of standards like
XPath unusable.
At the very least this should be only available if the server supports it
(with a capability URI)



> <RR> So we need an update to RFC7951?
>
> Regards,
> Reshad.
>
>

Andy


>
>     /martin
>
>
>
>
>
>     >
>     > Lada
>     >
>     > >
>     > > How is this supposed to work with JSON?
>     > >
>     > >
>     > > /martin
>     > >
>     > > _______________________________________________
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>     > > [email protected]
>     > > https://www.ietf.org/mailman/listinfo/netmod
>     >
>     > --
>     > Ladislav Lhotka
>     > Head, CZ.NIC Labs
>     > PGP Key ID: 0xB8F92B08A9F76C67
>     >
>
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