Overview

In CPS-341 the POST operation to create a new data node was updated to bring support for a multiple data trees under a single anchor (or a single root "/" node). In order to achieve this, the JSON data containing multiple data trees are parsed into a Collection of data nodes.

This collection of data nodes is then converted to a List of Fragment Entities which is stored into the database.

From the above description it is clear that when a GET operation will be performed on an anchor containing multiple data trees to retrieve one or all data trees, it will be returned as a List of Fragment Entities as opposed to a single Fragment Entity being returned earlier.

It is to be noted here that the methods used for GET operation are not limited to Get a Node API and are reused in other API's as well. All the APIS discussed below internally call the getFragmentWithoutDescendantsByXpath()to retrieve the data trees. This epic covers the impact on all the API's due to the above mentioned changes in CPS core.

A common task across the API's is to maintain backwards compatibility as well.

References

Related Tasks/Jira/Wiki

Open Issues and Decisions

#APIIssue/DescriptionNotesDecision
1

Get a Node

Get operation should return all the data trees under the root when xpath is set to "/"

after discussion with Toine Siebelink it was decided to give priority to the GET operation first, before heading for other API's. A discussion with the architects is to be scheduled to discuss upon the following points:

  • should a separate end point be created which returns all the data trees under the root node
  • impact of ongoing versioning issue with CPS on the above point and backwards compatibility

after discussion with the architects it was decided to have a v2 of the GET API and the v2 will return all the data nodes in an array

  • To implement V2 of Get Data Node API
  • New API to return all data nodes when xPath is set to root.
  • Existing functionality to be used when existing xPath is queried
  • New API to return JSON array as response
2Response body of GET APIshould GET Data Node return a JSON array or JSON object in response for multiple data trees

as discussed in weekly meeting, it was decided that v2 of the GET API will return JSON Array and v1 will remain as is (that is returns single data node as JSON Object)


3Impact on NCMP DMI pluginimpact analysis of Get Data Node returning multiple data trees on NCMP DMI pluginThe task is not of high priority as of now. As per CPS-sub team discussion this task was put on hold.
  • Not a priority task
  • Put on hold
4Update Data Node API

Update data node had inconsistencies where, updating leaf nodes for multiple container nodes would throw unexpected error.

And updating multiple list items in a list data node would cause partial update operation

After presenting the findings for patch operation and as per discussion in CPS sub team daily call, it was concluded that support for Patch operation for multiple data nodes would solve the inconsistencies found in the existing Patch operation.Support for Patch for multiple data nodes to be implemented.

List of impacted API's

OperationAPIIssuesPossible Solution

GET

Get a Node

  • should return all the data trees when xpath is set to root(/)
  • currently returns only the first data tree
  • modify the existing code for Get a Node API so it returns a List of fragment entities
  • this impacts other API's as well which make use of the Get operation
  • a separate API can be developed to return all the data trees, similar to Get all anchors and Get one anchor API in CPS

PUT

  • Replace a node with descendants

  • Replace list content


  • No issues were found in Delete DataNode API
  • Following tests were performed
    • replacing multiple Data Nodes under one container node
    • replacing multiple Data Nodes under multiple container nodes (under root node xpath)


DELETEDelete a datanode
  • No issues were found in Delete DataNode API
  • Following tests were performed:
    • Individual data nodes were deleted and the ones not deleted were retrieved successfully
    • When all data trees are deleted individually, the entire data node gets deleted from the DB eventually, i.e. an empty collection is not left behind when all data trees are deleted individually
    • When deleting using root node xpath, all container nodes are deleted.


PATCH

Update node leaves

Update node API should support Patch operation for multiple data nodes.

  • Patch operation should allow user to update multiple leaf nodes for multiple container/list data nodes.
POSTAdd list element to existing list
  • No issues were detected in Add list element API. The following tests were performed
    • Adding a single list item to existing list in DB
    • Adding multiple list items to existing list in DB
  • The list items are successfully added to the existing list


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