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Issues and Decisions

Overview

Currently when persisting any data in CPS the data validation is performed using the yang schema and upon successful validation the data is stored in CPS DB. But in case the data validation fails a 500 response is returned by CPS.


So, in case the data fails the validation check there is no way for the user to know the exact cause of failure. The failure is logged and can be seen in the container logs:

Logged error 
{"logTimeStamp":"2024-06-19T09:28:15.909Z","logLevel":"ERROR","traceId":"a0360e58c95bc63f6ff9f873c796e51c",
"principalId":"cpsuser",
"serviceName":"cps-application",
"message":"Exception occurred",
"spanId":"81b44b7a14f8fecb",
"processId":"1",
"threadName":"qtp1504320796-24",
"class":"o.o.c.r.e.CpsRestExceptionHandler",
"exception":"\norg.onap.cps.spi.exceptions.DataValidationException: Failed to parse json data. Unsupported xpath or json data:{}
at org.onap.cps.utils.YangParserHelper.parseJsonData(YangParserHelper.java:129)
at org.onap.cps.utils.YangParserHelper.parseData(YangParserHelper.java:88)
    /....
    a lot of logged data 
    ...../
at java.base/java.lang.Thread.run(Unknown Source)\nCaused by: java.lang.IllegalStateException: Schema node with name books was not found under (urn:ietf:params:xml:ns:netconf:base:1.0)data.
at org.opendaylight.yangtools.yang.data.codec.gson.JsonParserStream.resolveNamespace(JsonParserStream.java:410)
at org.opendaylight.yangtools.yang.data.codec.gson.JsonParserStream.read(JsonParserStream.java:308)
at org.opendaylight.yangtools.yang.data.codec.gson.JsonParserStream.parse(JsonParserStream.java:193)
at org.onap.cps.utils.YangParserHelper.parseJsonData(YangParserHelper.java:122)
... 175 common frames omitted\n\n"}

This is not very helpful for the user as it does not provide proper information about the root cause of failure.

Proposal

The idea here is to have a mechanism to validate the data and throw an appropriate response with message, before the data is persisted in the database. This validation check is not meant to be limited for new data but should also extend to sub-parts of a larger data set, such as data used in case of an update operation. So based on this the following approaches are proposed to perform a validation on data:

  • A new endpoint to validate the JSON payload against an existing schema in CPS DB, this endpoint will only validate the data and never persist it.
  • A dry-run flag in the existing CPS API's which would validate the data and return a response containing the details of validation failure. This flag can be implemented to multiple CPS APIs such as POST (Create a Node), PATCH (Update a Node) and PUT (Replace a node), where we can validate the entire data or parts of data and return the exact point of failure in the validation as part of response.

Implementation Ideas

In either case the endpoint should return a REST response with appropriate code and message. 

  • Response Code: 400
  • Response Body: a JSON response providing details about the failure. (response body format to be finalized)

List of impacted APIs


NameEndpointIssueRequired Action
1Create a Node/{apiVersion}/dataspaces/{dataspace-name}/anchors/{anchor-name}/nodesReturns 500 status on data validation failure

Return 400 status with updated and detailed error message.

Updated Message:

{
"status": "400 BAD_REQUEST",
"message": "Data Validation Failed",
"details": "Failed to parse JSON data. 
Data node with name "Node" was not found 
under Schema Node "categories"."
}
2Update Node Leaves/{apiVersion}/dataspaces/{dataspace-name}/anchors/{anchor-name}/nodesReturns 400 status with entire JSON payload in error message
3Replace Nodes/{apiVersion}/dataspaces/{dataspace-name}/anchors/{anchor-name}/nodesReturns 400 status with entire JSON payload in error message
4Add List Element/{apiVersion}/dataspaces/{dataspace-name}/anchors/{anchor-name}/list-nodesReturns 500 status on data validation failure
5Replace List element/{apiVersion}/dataspaces/{dataspace-name}/anchors/{anchor-name}/list-nodesReturns 400 status with entire JSON payload in error message
6Get Delta between anchor and JSON payload/v2/dataspaces/{dataspace-name}/anchors/{anchor-name}/deltaAnchorsReturns 400 status with entire JSON payload in error message

Example

The following example shows the expected changes to existing APIs to implement a dry-run flag:

#API

Request parameters

Response CodesScenarios
1

Create a Node:

/v2/dataspaces/{dataspace-name}/anchors/{anchor-name}/nodes

Parameter NameInRequiredDescription
dataspace-namePathtruedataspace name
anchor-namePathtrueanchor name
xpathQuerytruexpath of node
dry-runQueryfalse

flag to enable or disable data validation

(set to false by default)

  • 200 (OK)
    • success
  • 400
    • dataspace not found
      DataspaceNotFoundException
    • anchor not found
      AnchorNotFoundException
    • Data node not found
      DataNodeNotFoundException
    • invalid xpath
      CpsPathException
  • 500
    • unexpected error

Scenario 1: dry run set to false

In this case there will be no functional change in the APIs, and they would return appropriate response codes with messages in case of any failure.

Scenario 2: dry run set to true

In this case the APIs will return the same response codes. The only difference will be, in case data validation passes, then it would return a 200-response code, but the data will not be persisted in case of POST operation or modified in case of PUT/PATCH operations.

References:


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