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
- - CPS-1391Getting issue details... STATUS
- - CPS-341Getting issue details... STATUS
- CPS-341 Spike: Support multiple data tree instances under 1 anchor
Open Issues and Decisions
# | API | Issue/Description | Notes | Decision |
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1 | 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:
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 |
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2 | Response body of GET API | should 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) | |
3 | Impact on NCMP DMI plugin | impact analysis of Get Data Node returning multiple data trees on NCMP DMI plugin | The task is not of high priority as of now. As per CPS-sub team discussion this task was put on hold. |
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4 | Update 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
Operation | API | Issues | Possible Solution |
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GET | Get a Node |
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PUT |
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DELETE | Delete a datanode |
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PATCH | Update node leaves |
| Update node API should support Patch operation for multiple data nodes.
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POST | Add list element to existing list |
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