Submodels

[HRogge]

This extension of yangson allows the user to hook multiple YANG trees together into a larger schemata without manually joining them. This make it easy to add IETF defined subtrees like "ietf-yang-library:modules-state" and process incoming requests in one yangson call.

[llhotka]

Hmm, this is quite a substantial change. Can you be more specific about its purpose? Is it similar to schema mount [RFC 8528]?

[kwatsen]

I don’t support adding more features to Yangson until the XML-feature is solid.

I’m concerned about what XML-testing has been performed. What is needed are for XML-oriented test cases to be added to test/test_module.py, such as:

1. convert the configuration to/from XML (add support for anydata/anyxml? - a callback function?)
2. convert the “action” statement’s input/output to/from XML (add an ‘input’ statement?)
3. convert the “rpc” statement’s input/output to/from XML
4. convert the “notification” statement input to/from XML

It may be that this PR is needed in order to process the nodes from the "subtest" module, but I don't see it yet.

[HRogge]

I was unaware of RFC 8528, but I think it should be the same or similar...

I am using it to multiple YANG definition files into a larger YANG specification without any need to edit them.

In my server I ususe the "ietf-restconf@2017-01-26.yang" unified model as a base... then hook in (at the "data" node) the users YANG model... than add the RPCs under the "operations" node (and so forth with "ietf-restconf-monitoring:restconf-state" and "ietf-yang-library:modules-state").

This makes it very easy to construct a representation of all Restconf nodes the server uses, which makes input and output checking very easy. No need to parse the incoming GET/PUT/POST Paths by hand to decide that I have to add the modules-state to the output, I can just add it to the instance data.

[HRogge]

I don’t support adding more features to Yangson until the XML-feature is solid.

I’m concerned about what XML-testing has been performed. What is needed are for XML-oriented test cases to be added to test/test_module.py, such as:

I have a set of (machine readable) XML and JSON testcases I collected from the RFCs that I use to verify me servercode at https://github.com/fkie/ietf-restconf-testcases .

1. convert the configuration to/from XML (add support for anydata/anyxml? - a callback function?)
   anydata/anyxml is a mess... I am not even sure how to resolve this in general.

2. convert the “action” statement’s input/output to/from XML (add an ‘input’ statement?)
   I am already doing this with the XML code in place.

3. convert the “rpc” statement’s input/output to/from XML
   I am already doing this with the XML code in place.

4. convert the “notification” statement input to/from XML
   My server lacks the notification support, so I am not sure about this one.

[kwatsen]

It is comforting to see the testing that exists for your server. But I think that XML-oriented tests need to exist in the Yangson tree as well.

Regarding #1, yes, anydata/anyxml is a mess. It's okay for Yangson's XML-oriented tests to skip the anydata/anyxml nodes for now...at least until everything else is working. FWIW, my app does have/use anydata (e.g., ietf-restconf:errors/error-info), so this isn't something I can ignore for long.

Regarding #4, a Yangson test would just serialize/deserialise a known-good instance document - no other "processing" needs to occur, AFAICT.

[HRogge]

I wonder what would be needed to use the same kind of tests with Yangson... maybe each test could have a JSON and a XML version of input output and we could test Yangson by converting between the two?

An alternative would be to build a Yangson Data instance object "by hand" (in python code).