Re: [netmod] draft-ietf-netmod-geo-location-01: an optional location info

Ladislav Lhotka <lhotka@nic.cz> Thu, 11 July 2019 10:45 UTC

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From: Ladislav Lhotka <lhotka@nic.cz>
To: Jan =?utf-8?Q?Kundr=C3=A1t?= <jan.kundrat@cesnet.cz>, netmod@ietf.org
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Date: Thu, 11 Jul 2019 12:44:43 +0200
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Subject: Re: [netmod] draft-ietf-netmod-geo-location-01: an optional location info
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Jan Kundrát <jan.kundrat@cesnet.cz>; writes:

> Hi, I'm augmenting the ietf-network and ietf-network-topology 
> from RFC 8345,  trying to add geolocation information to the 
> network nodes. I found your  draft (thanks for it!), 
> draft-ietf-netmod-geo-location-01. What I am  struggling with is 
> adding the geolocation as an *optional* element. 
> 
> When I try this YANG construct: 
> 
>   augment "/nw:networks/nw:network/nw:node" { 
>     when "../nw:network-types/my-topo:topology-type"; 
>     description "Optical elements within a network"; 
> 
>     uses geo:geo-location; 
>   } 
> 
> ....then my YANG instance data validator, libyang, complains 
> when the  location is missing:

The "location" choice is defined as mandatory, so an instance of 
one of the cases must be present. I don't know whether it is 
necessary or not, but you can avoid it easily by overriding the 
definition:

      uses geo:geo-location {
          refine geo-location/location {
              mandatory false;
          }
      }

Ahoj, Lada
 
> 
> err : Mandatory choice "location" missing a case branch. 
> (/ietf-network:networks/network[network-id='...']/node[node-id='...']/my-topo:location/geo-location) 
> 
> I can do the augmentation with one more container (a presence 
> one) like  this: 
> 
>   augment "/nw:networks/nw:network/nw:node" { 
>     when "../nw:network-types/my-topo:topology-type"; 
>     description "Optical elements within a network"; 
> 
>     container location { 
>       presence true; uses geo:geo-location; 
>     }     
>   } 
> 
> The resulting data then contain an extra level of nesting. I 
> think that  this is suboptimal. 
> 
> I have two questions: 
> 
> - Is that perhaps a bug in libyang?  - If libyang is correct, is 
> there a way of making the location info  optional without that 
> one more level of nesting? 
> 
> Also, the example does not work as-is because it's importing the 
> module  using a wrong name. Here's a tiny patch: 
> 
> index 7bd8622c..088621a1 100644 --- 
> a/experimental/ietf-extracted-YANG-modules/ietf-uses-geo-location@2019-02-02.yang 
> +++ 
> b/experimental/ietf-extracted-YANG-modules/ietf-uses-geo-location@2019-02-02.yang 
> @@ -2,7 +2,7 @@ module ietf-uses-geo-location { 
>    namespace 
>      "urn:ietf:params:xml:ns:yang:ietf-uses-geo-location"; 
>    prefix ugeo; 
> -  import geo-location { prefix geo; } +  import 
> ietf-geo-location { prefix geo; } 
>    organization "Empty Org"; contact "Example Author 
>    <eauthor@example.com>";; description "Example use of 
>    geo-location"; 
> 
> The -00 version was correct in this, BTW. 
> 
> With kind regards, Jan 
> 
> _______________________________________________ netmod mailing 
> list netmod@ietf.org 
> https://www.ietf.org/mailman/listinfo/netmod 

-- 
Ladislav Lhotka Head, CZ.NIC Labs PGP Key ID: 0xB8F92B08A9F76C67