NETCONF-based RPC/action replies cannot be parsed

[kwatsen]

RFC 7950 says in both Section 7.14.4 and Section 7.15.2:

If output parameters are returned, they are encoded as child elements to the <rpc-reply> element <snip/>

However, consistent with RFC 8040, Section 3.6.2, the various tests in test_model.py for rpc and action responses all expect an output container to be returned:

• yangson/tests/test_model.py

  Line 233 in 83ad93f

  "testb:output": {

• yangson/tests/test_model.py

  Line 827 in 83ad93f

  "testb:output" : {

• yangson/tests/test_model.py

  Line 833 in 83ad93f

  <output xmlns="http://example.com/testb">

• yangson/tests/test_model.py

  Line 923 in 83ad93f

  "test:output" : {

• yangson/tests/test_model.py

  Line 929 in 83ad93f

  <output xmlns="http://example.com/test">

For NETCONF, it seems that the string "output" needs to be replaced with the name of the rpc or action.

Bonus issue/effort: the tests for rpc and action requests should be doublechecked as well.

[llhotka]

Hmm, so do you suggest to remove the output container from instance data? This could work for JSON but probably not for XML, if there are multiple elements in reply data.

[kwatsen]

That is one option but, as you say, the XML would have an issue, unless we use a fake container like this one in list-pagination-rc.

My preferred option is to think about how to fix the problem in NETCONF (i.e., NETCONF-next). My recommendation would be to make the NETCONF-response be the same as the RESTCONF response. That is, have an output element under the rpc-reply element.

Looking at RFC 7950 for examples, I find that the rpc response example is unhelpful for this illustration. Thankfully, the action response example has output, and the same output is used for the rpc-response and action-response. This is the relevant part:

CURRENT:

     <rpc-reply message-id="101" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
       <reset-finished-at xmlns="urn:example:server-farm">2014-07-29T13:42:12Z</reset-finished-at>
     </rpc-reply>

I proposal changing this to:

NEW:

     <rpc-reply message-id="101" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
       <output xmlns="urn:example:server-farm">
           <reset-finished-at>2014-07-29T13:42:12Z</reset-finished-at>
       </output>
     </rpc-reply>

Note that the xmlns is moved to the output element.

If we can agree that this is a good/proper update for NETCONF-next, then we can discuss options for Yangson.

Some options:

• document that the calling code is responsible for converting the XML to have the output container, before calling from_xml()
• provide a "convenience" API to convert the XML to have the output container, before calling from_xml()
• add a parameter to the from_xml method to convert the XML to have the output container.

Thoughts?