CPS-391 - Getting issue details... STATUS

Guiding Principles

  1. NCMP REST Interface will follow/be inspired by RESTConf interface for easy acceptance of and transition to this interface
  2. Will follow ONAP's RESTful API Design Specification 
  3. The interface will include the concept of data-stores inspired by Network Management Datastore Architecture (NMDA) and as used in RESTConf
  4. The application should be able to easily switch between 'pass-through' and other datastores (also identical rest endpoint and responses)

References

Follow principles/patterns of RESTCONF RFC-8040 https://datatracker.ietf.org/doc/html/rfc8040
Follow principles/patterns of yang-patch RFC-8072 https://datatracker.ietf.org/doc/html/rfc8040
Follow principles/patterns of RESTCONF NMDA RFC-8527 https://datatracker.ietf.org/doc/html/rfc8527

Issues & Decisions


IssuesNotesDecisions
1KPI for De-registration of 100 CM-handlesThis was mentioned. Was this ever agreed, is this a valid use case that needs to be covered together with the Registration ?

Not priority for now, but acceptable if we match the registration req.
#2 for de-reg  
kieran mccarthy Kolawole Adebisi-Adeolokun 

2DMI delayCould we get some feedback on DMI-delays for other use cases as not mentioned in FS document

Awaiting for ETH feedback AP On Kolawole Adebisi-Adeolokun and Csaba Kocsis


Provided

3

Number of instances


In some cases, ETH have used 2 instances, can we verify the number of instances for each use case.

Some of the req were defined per instance and resources used : Identify which of these ? 

Agreed to;

CPS use 1 instance currently, but should focus on aligning performance with 2 instances for all use case 

4Input Load Distribution the CM-handle search and ID search

Currently has 5 parallel request between them distributed at 2.5 each. This fractional distribution isn't feasible for parallel processing; the load should be allocated as whole numbers. Load needs to be distributed at. Would it be acceptable to adjust this distribution to either 2 or 3 parallel requests each (and vice versa ) without any negative repercussions?


Agreed to do 6 parallel request combined total and divide the load to 3 parallel request each

5Regarding CM-handle search and ID search

FS only identified Module performance, are there any testing done towards a combined search of properties and modules in a single query


Confirmed no other testing was previously done on this.....  

CPS have the capabilities to do mixed testing. ETH tbc on if they want to consider this ( Csaba Kocsis )


Requirements

Please note this section was added long after the implementation and focuses on characteristic and enhancements after this study only.

CPS-2249: NCMP To support Conflict Handling (Policy Execution) using External Service

Functional: CPS Impacts Policy Executor


InterfaceRequirementAdditional InformationSignoff
1CPS-E-05

Write operations are intercepted and validated using the new external service.
No effect on existing behavior if the result is 'Allow'



2CPS-E-05When the External validation is negative NCMP REST Response should be '409 Conflict'.  The HTTP status message should contain the message and decision id from the external validation service.NCMP interface validation shall be done before the external validation (Conflict management)
3CPS-E-05

NCMP to provide metrics on external validation

AP on CPS to provide the metrics (Kolawole Adebisi-Adeolokun )

Error Handling


ScenarioExpected BehaviorNotesSignoff
1External validation service does not respond (in time) Or does not respond with 2xx (Http status code)

configurable default answer


This needs further investigation AP Gergely Molnar  

Possible proposal:

  • Implement watchdog similar to DMI health check

2Unrecognized response from External Validation

(Low prio)

No default behavior covered yet in //, 

If not reachable - default accept/reject with specific message



3CM Handle ID without Alternate Id (fdn)




Characteristics


ParameterExpectationNotesSignoff
1Performance impact? 
  • External Validation Response time depends on various response time at the moment

Characteristics

It is proposed that reported characteristics will be used as a baseline for NCMP when agreed and sign-off.


OperationConcurrent requests/parallelDMI DelayResponse sizePerformance Requirement
(Blue Stone tablet KPI)
NotesSign-Off
1Registration of 20,000 CM-handles
(in batches of 100)
1 (requests are sequential)

100 ms to get module references
1,000 ms to get module resources

N/A

  • 11 CM-Handles/second as per Stone Tablet E2E Wich include module conversion warm-up
  • NCMP Budget: 22 Cm Handles/second 
  1. Batch Size: 100 (per request)
    Not using Module Set Tags
  2. Time measured start of first rest-call until all cm handle states READY
  3. 1,000 unique module references.
  4. Five different types of Nodes. So 5 requests for Module Resources. Avg 200 modules each.
2De-registration of 100 CM-handles1 (requests are sequential)

No Module delays

N/A

  • 11 NEs/second
  • NCMP should target 22 NEs/Second 

De-registration is currently not mentioned in Stone Tablet KPI or FS, however we have agreed to match the performance of registration for now as de-reg is also not a priority at this point in time




3CM-handle ID search with Module filter

3
Run in parallel with #4

N/A20,000 CM Handles i.e.
100*20.000 = 2MB

As provided byCsaba Kocsis 0.625 seconds/Operation

FS stated 5 parallel request for both ID search and search.  CPS to run with 3 parallel each for both ID search and Search meaning a combine total of 6 parallel request 
4CM-handle search with Module filter3
Run in parallel with #3
N/A20,000 CM Handles i.e.
500*20.000 = 10MB

As provided by Csaba Kocsis 13 seconds/Operation

FS stated 5 parallel request for both ID search and search.  CPS to test with 3 parallel each for both ID search and Search meaning a combine total of 6 parallel request 
5Synchronous single CM-handle pass-through read

10
Run in parallel with #6

5 KB

25 (parallel) request/sec

Read are done in parallel with Write

6Synchronous single CM-handle pass-through write (CUD)

10
Run in parallel with #5

670 msCsaba Kocsis 

5 KB

13 (parallel) request/sec

No response is expected

Notes

  1. This is for mixed TCs
  2. Single KPIs will be monitored in NCMP owned pipeline with our performance every day(2 hrs interval) - Performance


Synchronous single cm-handle pass-through (read) requests

Parameter

Expectation

Notes

Sign-Off

Average Response Size
5KB
Shall not exceed 5KB
Concurrent request12 clients requests toward 1 NCMP simultaneously
DMI also support 12 simultaneous requests

40ms of overhead on top of DMI latency for each requests, at most for NCMP request. This shall remain within 40ms for 12 parallel requests. 

Given the DMI delay below; this means up to 240 request per second

DMI Delay10ms 

This is not in control of CPS. 
So for performance testing our stub should simulate a 10ms delay

Assume DMI is 1.25 seconds average DMI response time for high latency, low latency =10 ms, this should also work for DMI Plugin. I.e 40ms ontop of the DMI. 1.25seconds+40ms= 1.29seconds

Test Environment
  1. CPS and NCMP

requests:
    cpu: 2000m
    memory: 2Gi
limits:
    memory: 3Gi
    cpu: 3000m

2. Postgres

requests:
    cpu: 4000m
    memory: 1Gi
 limits:
    memory: 3Gi
    cpu: 6000m


Security

Disable Basic Authentication in Springboot

If configurable from application yaml, then it’s acceptable.

Open Issues & Decisions



Description

Notes

Decision

1Priority of async calls
In Istanbul, async calls are required only in pass-through cases. NCMP does not have to handle these requests 
2Will we use the data node wrapper on GET rest operations?

Currently, we wrap the response of GET operations using the data node wrapper.

we should mainly support yang-data/json

controlled by "accept-header"

3In the URI will we distinguish between data and operations (RFC calls) as part of the path?

This only applies to pass-through

yes, we will distinguish between data and operation

4Which query parameters will NCMP support?

Parent data resource identifier can handle any path using the same query parameter 

  1. cpsPath
  2. RESTConf Path (pass-through)
  3. Proprietary Path (pass-through)
5

Yml should include return types and examples of the payload


Legacy and new API documentation needs to include output examples.

Task created, see  CPS-401 - Getting issue details... STATUS

6camel case or dash in URI

We will use a dash for param names e.g. cmHandle (although it has since been agreed we use 'ch' in this particular case)

See no.3 https://restfulapi.net/resource-naming/

7Insert /resourcePath in front of the resource path to prevent ambiguous paths<OP>/ncmp/<v{vNumber}>/ch/<cmHandle>/<data|operations|{ncmp-operation}>/ds/{datastore}/[rp:]{resourcePath}?{query}Optionally insert the resource path ('rp:') if it clashes with the current
8Granularity of update scenarios (and priority)
  1. Add child and its descendants (supported in cps core)
  2. Add all list elements (supported in cps core)
  3. Replace child and its descendants (supported in cps core)
  4. Replace all list elements (pending in cps core)
  5. Update single leaf (new)
  6. Add list entry (new)

Priority is pass-through only so it depends on the RETSConf protocol that is supported.

In Jakarta or if required by other projects more fine-grained 'operation' datastore update options can be implemented

9Fallback option for datastore in release I
No, explicit datastore options will be used in Istanbul
10fields is a rest conf option, investigate is it fully supported by onap
Supported in pass-through for ONAP DMI plugin but depending on the support by the actual target. The intention is to increase support 'fields' in future requirements following RFC-8040 for operational datastore etc.
11Agree on URI syntax 

Proposed syntax by CPS team 

<OP>/ncmp/<v{vNumber}>/ch/<cmHandle>/<data|operations|{ncmp-operation}>/ds/{datastore}/[rp:]{resourcePath}?{query}

review completed and proposed URI agreed 
12Will we combine query capabilities with update capabilities?
We have decided not to combine query capabilities with update capabilities
13Description of header limitations

HTTP Header Limitations
Some servers put size limitations on HTTP headers, making them unsuitable for storing cmHandle information.

LIMITATION NOTE: server implementations put size limits on the headers meaning header contents should be designed carefully :
Apache - 8K
Nginx - 4K-8K
IIS - 8K-16K
Tomcat - 8K – 48K

14Will NCMP support paths for pass-through:running

The plugin will not do transformation or validation of paths in the case of pass-through:running

15Specification of path per cm handle
DMI Plugin can take cps paths or restconf paths and it needs to specify that per cm handle when cm handle is created
16What is the default path for NCMP
In NCMP default will always be cps path and depending on the adapter we can change it as needed per cm handle
17Fields parameter for ncmp/operational?
The fields parameter is ignored in ncmp/operational (in Istanbul release)
18Is specifying the datastore mandatory?
Datastore is mandatory in Istanbul release
19Register a DMI plugin with NCMP
DMI plugin is a part of cm handle registration. The rest endpoint on NCMP can be multiple calls
20Retrieve list of modules (names) for a cmHandle
Retrieve a list of module names for cm handle - this will be used by ncmp to get the models. - assuming ncmp model discovery is complete and it is stored in cps core, this will come from cached information
21Where will sync be implemented?
Implement sync in the dmi plugin and then have ncmp be able to pass on the request. This is not a bulk operation
22Config-true only support (filter out config-false data)
Use datastore 'running' to select this but filtering not supported in I for cached data
23Enable NCMP to convert cpsPath to mutliple options(RESTConf, netConf, leave as cpsPath)When other DMI-Plugins are realized they might need a different conversion then the default from cspPath to RESTConf. This could be configured by using a known property for each cmHandle Not required in Istanbul. But DB model can easily be updated to cater for this when needed
24Datastore conversion in NCMP or DMI-PluginDMI-Plugin will know best how to convert. This will also reduce future impacts on NCMP for new options.NCMP will do now conversion of datastore names
25What datastore/s (name/s) is/are supported by NCMP to referred to the cached data. 'Operational' or 'running''operational' would imply RO and config=false data is included. 'To also support 'running' using the same data a filter would have to be appliedsee supported datastore in I : Datastores
26Consider fallback option when user specifies ncmp/operational but data is NOT synced
NCMP will forward requests for un-synced cmHandles to the DMI Plugin
(Including required transformation of resource path etc.)
27Support for &fields parameter when using cached data
  1. not supported (ignored, not rejects, nice for future compatibility)
  2. treat as 'no descendants'  (low cost)
  3. use to filter cached data

&Fields parameter will be ignored for 'cached' data in Istanbul timeframe 

long term expectation is to have support following RESTConf/ODL behavior as much as possible

28Support for &fields parameter when forwarding to plugin for non-synced cmHandles
  1. not supported (ignored, not rejects, nice for future compatibility)
  2. treat as 'no descendants'  (low cost)
  3. translate (insert module names) and forward

A spike  CPS-455 - Getting issue details... STATUS  will be executed to determine the feasibility of option 3 and decide if it can make Istanbul scope

29Response for Data Sync request (in Istanbul timeframe)The action is blocking synchronous through whole stack (in I) so response could include the data returned by the node. However this seem incorrect for an 'action' so maybe the response should just be just an acknowledgment it is 'done'No need to return data,  just HTTP Code 200 (OK) will suffice

RESTCONF/NETCONF relationship

NCMP URI

NCMP URI format to follow below pattern

<OP>/ncmp/<v{vNumber}>/ch/<cmHandle>/<data|operations|{ncmpAction}>/ds/{datastore}?[rp:]{resourcePath}&{options}

Below table shows the proposed interface, actual implementation might deviate from this but can be accessed from

URI
Mandatory or Optional
<OP>the HTTP methodMandatory
ncmp /the ncmp root resourceMandatory
<v{vNumber}>version of the ncmp interface <path> is the target resource URI <query> is the query parameter listMandatory
ch/<cmHandle>unique (string) identifier of a yang tree instance.Mandatory
<data|operations|{ncmpAction}>request category - yang data, rpc operation or a (non-modelled) ncmp api action. this could be data, operations or ncmpAction (e.g. 'sync-data')Mandatory
ds/{datastore}
Mandatory
<resourceIdentifier>the path expression identifying the resource that is being accessed by the operation. If this field is not present, then the target resource is the API itself.Optional
<options>

Parameters with the familiar form of "name=value" pairs. Query parameters are optional to implement by the server and optional to use by the client. Each optional query parameter is identified by a URI

Optional

DMI should be able to support (/pass through) ANY parameter associated with the RESTCONF message; see Section 3.4 of [RFC3986].

Datastores

New datastores are defined for ncmp to access the CPS 'running' or 'operational' datastore.
Alternatively, the request can be sent directly to the 'device' itself (bypassing CPS datastores) using one of the 'passthrough-*' datastores options as below

The new ncmp datastores required for ONAP Release I include :

CPS-333 Network Configuration Management (NCMP) scope for I release considerations

Datastore Mapping in ONAP DMI Plugin impl.

#Incoming DS value (NCMP & DMI Rest interfaces)Outgoing (non-NMDA RestConf controller)Notes
1/ds/ncmp-datastores:operational
content=all
CT + CF, RO
2/ds/ncmp-datastores:running
content=config
CT, RW
3/ds/ncmp-datastores:passthrough-operational
content=all
CT + CF, RO
4/ds/ncmp-datastores:passthrough-running
content=config
CT, RW
5/ds/<anything-else>N/ANot supported

  

Datastore, Paths and Format Combinations for Read Operations


StateInputBehaviorDataNotes
#Data-Sync Datastore parameter

Expected resourcePath

format

Accept-Header

Fields

(filter)

Data Source

Included DataNodes
(config)

1OnNot SpecifiedcpsPathapplication/yang-data+jsonN/ANot supportedN/AN/A
2OnNot SpecifiedcpsPathapplication/jsonN/ANot supportedN/AN/A
3Off

Not Specified

cpsPathapplication/yang-data+json

N/A

Not supported

N/AN/A


4OffNot SpecifiedcpsPathN/AN/ANot supportedN/AN/Athere are NO DataNode objects in CPS to output as JSON)
5OffNot Specifiedother then cpsPathN/AN/ANot supportedN/AN/ANot supported Since NCMP can only convert cpsPaths
6On | Offncmp/passthrough-operational

NCMP does not parse

NCMP does not parsedepends on DMI-Plugin
(supported in ONAP)

Resolve DMI plugin

Forward request to plugin

Output received response
DMI-Pluginconfig +
non-config

The DMI plugin may error if the RP or accept header are not supported.

The DMI plugin may forward the request without processing too.
7On | Offncmp/passthrough-runningNCMP does not parseNCMP does not parsedepends on DMI-Plugin
(supported in ONAP)

Resolve DMI plugin

Forward request to plugin

Output received response
DMI-Pluginconfig-only
8Onncmp/operationalcpsPathapplication/yang-data+json
  • Not supported in Istanbul releases.
  • Considered for Kohn Release

Read from cache

output: application/yang-data+json

CPS-Coreconfig +
non-config
NCMP/CPS-Core needs to remove DataNode wrapping

9Onncmp/operationalcpsPathapplication/json
  • Not supported in Istanbul releases.
  • Planned for Kohn Release

Read from cache

output: application/json

CPS-Coreconfig +
non-config

Output will use DataNode wrapping (as is from CPS-Core)

For forwarding (cached config off) dmi-reposne need to be wrapped explicitly in 'DataNode'

10Offncmp/operationalcpsPathapplication/yang-data+json

to be determined in spike, see issue #28


Resolve DMI plugin

Convert cpsPath to RESTConfPath*

Forward request to plugin | Read from DMI plugin

Output application/yang-data+json

DMI-Plugin

config +
non-config


11On | Offncmp/runningcpsPathapplication/yang-data+jsonto be determined in spike, see issue #28

Resolve DMI plugin

Convert cpsPath to RESTConfPath*

Forward request to plugin | Read from DMI plugin

Output application/yang-data+json

DMI-Pluginconfig-only

*Note Convert cpsPath to RESTConfPath wil only support 'absolute' cpsPath for conversion no query-type paths

Read Example

Read with fields
{ncmpRoot}/ncmp/v1/ch/<cmHandle>/data/ds/<datastore>/{dataResourceIdentifier}?fields={fieldsExpression}


URI :{ncmpRoot}/ncmp/v1/ch/node123/data/ds/ncmp-datastores:operational/TopElement[@id=1]/SomeFunction[@id=1]?fields=cell-model:Cell/attributes(attr1;attr2)
 
Header :
      Accept : application/yang-data+json
 
Response :
      200 OK
{
  "function-model:SomeFunction": [
    {
      "id": "1",
      "cell-model:Cell": [
        {
          "id": "Cell-001",
          "attributes": {
            "attr1": "value1",
            "attr2": "value2"
          }
        },
        {
          "id": "Cell-002",
          "attributes": {
            "attr3": "value3",
            "attr4": "value4"
          }
        }
      ]
    }
  ]
}



Works Items for above.

#DescriptionComponentEnables
1Forward request from NCMP to CPS-CoreNCMP8,9
2Forward request from NCMP to DMI-PluginNCMP6,7
3Convert json (dataNode) to yang-data+jsonCPS-Core/NCMP8
4Convert cpsPath to RESTConf PathNCMP10,11
5Enhance &fields parameter where neededNCMP10,11+fields option
6NOT SupportedN/A1,2,3,4,5

Datastore, Paths and Format Combinations for Write Operations

  • Write operations are only supported on the ncmp-datastores:running and ncmp-datastores:passthrough-running datastores
  • The Data Target for all write operation is DMI-Plugin
  • Write operations are only supported for config=true data
  • Fields and similar parameters are not supported for write operations

StateInputBehaviorNotes
#Data-Sync OperationDatastore parameter

Expected resourcePath

format

Content-Type
1On | OffCreatencmp/passthrough-running

NCMP does not parse

NCMP only checks it is valid JSON, then embeds the data in a larger JSON structure (see CPS-390 page)

Resolve DMI plugin

Forward request to plugin

Output received response (success or failure)

The DMI plugin may error if the RP or content type are not supported.

The DMI plugin may forward the request without processing too.
2On | OffReplacencmp/passthrough-running

NCMP does not parse

NCMP only checks it is valid JSON, then embeds the data in a larger JSON structure (see CPS-390 page)

Resolve DMI plugin

Forward request to plugin

Output received response (success or failure)

The DMI plugin may error if the RP or content type are not supported.

The DMI plugin may forward the request without processing too.
3On | OffDeletencmp/passthrough-running

NCMP does not parse

NCMP doesn't expect any input data from application, will create request body to DMI plugin without embedded data.

Resolve DMI plugin

Forward request to plugin

Output received response (success or failure)

The DMI plugin may error if the RP or content type are not supported.

The DMI plugin may forward the request without processing too.
4On | OffPatchncmp/passthrough-running

NCMP does not parse

NCMP only checks it is valid JSON, then embeds the data in a larger JSON structure (see CPS-390 page)

Resolve DMI plugin

Forward request to plugin

Output received response (success or failure)

The DMI plugin may error if the RP or content type are not supported.

The DMI plugin may forward the request without processing too.
5On | OffCreatencmp/runningcpsPathapplication/yang-data+json

Resolve DMI plugin

Convert cpsPath to RESTConfPath

Forward request to plugin

Output received response (success or failure)


6On | OffUpdatencmp/runningcpsPathapplication/yang-data+json

Resolve DMI plugin

Convert cpsPath to RESTConfPath

Forward request to plugin

Output received response (success or failure)


7On | OffDeletencmp/runningcpsPathN/A

Resolve DMI plugin

Convert cpsPath to RESTConfPath

Forward request to plugin

Output received response (success or failure)


8On | OffPatchncmp/runningcpsPath

application/yang-data+json

(*plain patch)

Resolve DMI plugin

Convert cpsPath to RESTConfPath

Forward request to plugin

Output received response (success or failure)


9On | OffPatchncmp/runningcpsPathapplication/yang-patch+json

Resolve DMI plugin

Convert cpsPath to RESTConfPath

Forward request to plugin

Output received response (success or failure)


Write Example

Write Example
 

Sync & Model API

#Req/usecase

REST

Method

 URI

Request/Response Example
1DMI notifies NCMP of new , deleted or changed cmhandles DMI Plugin NCMP. Including initial registrationPOST{ncmpRoot}/ncmp/v1/ch/
Scenario : DMI notifies NCMP of new cmhandles
Method : POST
URI : {ncmpRoot}/ncmp/v1/ch/
Header :
Content-Type: application/json

Request Body
Request Body : {
      "dmiPlugin" : "onap.dmi.plugin", 
      "createdCmHandles" : [ {   "cmHandle" : "rf4er5454",
                                 "cmHandleProperties" :
                                   { "subSystemId" : "system-001" }
                             }, {..} ],
      "updatedCmHandles" : [ .. ],
      "removedCmHandles" : [ "node-1", "node-2" , ... ]
  }

json attributes:

  • "dmiPlugin" resolvable servicename
  • "createdCmHandles" used for initial cm handle registrations or subsequent
    cmhandle creations
  • "updatedCmHandles"
    Used for updates to cmhandles. Same structure as for create handles
  • "removedCmHandles"  array of cmhandles that have been deleted
    from the network (no additional properties
2Get all cm handles that support  all modules in a given list of modulesPOST

{ncmpRoot}/ncmp/v1/ch/searches

URI :  {ncmpRoot}/ncmp/v1/ch/searches


The minimal requirement is if we provide the AND query impl then for OR query the client can send multiple requests


Request Body

Content: application/json

Note: revision should be optional 

{
  "modules": [
    {
    "moduleName": "", (Mandatory)
    "revision": "" (Optional)
    }
  ]
}


Header :
Accept: application/json
Response:

Should return an array of objects as we may add more data in the future 
{
  "cmHandles": [
    {
      "cmHandleId": "xxx"
    }
  ]
}

3Request (trigger) Data SyncPOST

{ncmpRoot}/ncmp/v1/ch/<cmHandle>/syncData

Scenario : Client requests to sync a node

URI : {ncmpRoot}/ncmp/v1/ch/node123/syncData

Response   : HTTP-Status code (only, no body)

4Get model info for CMHandleGET

{ncmpRoot}/ncmp/v1/ch/{cmHandle}/modules

Scenario : Get the model data for CMHandle

URI :{ncmpRoot}/ncmp/v1/ch/2334dedf/modules

Header :
      Accept: application/json

Response:

  [
        {
            "moduleName": "nc-notifications",
            "revision": "2008-07-14",
        },
        {
            "moduleName": "ietf-tls-server",
            "revision": "2016-11-02",
        },
        {
            "moduleName": "ietf-ssh-server",
            "revision": "2016-11-02",
        }
    ]
5Get all the registered cmhandles for a given pluginGET{ncmpRoot}/ncmp/v1/dmiPlugins/{pluginId}/ch

Scenario : Get all cmhandles from NCMP for a given dmiPlugin. May be used
for conciliation
Method : GET
URI : {ncmpRoot}/ncmp/v1/dmiPlugins/{dmiPlugin}/ch
Header :
Content-Type: application/json

Response Body
Success Response :
    HTTP/1.1 200 Ok
Date: Thu, 26 Jan 2021 20:56:30 GMT
Server: example-server
  { "cmHandles" : [ {
          "cmHandle" : "node-1",
          "cmHandleProperties " : { "subSystem" : "system-001" }
       } ]
   }


NCMP / DMI Overview



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2 Comments

  1. "function-model:SomeFunction":
    when field function is used to list attributes in child will the parent still be part of output? (Joseph Keenan might be able to test this
    1. I will add this to the spike Toine Siebelink