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 | ||
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 | ||
4 | CPS Core API's under this link | The remaining CPS core API's might require modification with respect to decisions made for the GET operation. Based upon the decisions for the above Issue this table will be updated from time to time. | in the meeting it was decided to focus on GET operation first as the work on remaining API's seemed different from the one for the GET API. Also it was decided to first have a discussion with the architects regarding the GET API and then have a separate discussion for the remaining API;s. |
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 |
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POST | Add list element to existing list |
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The existing GET operation
//Returns single fragment entity default FragmentEntity findFirstRootByDataspaceAndAnchor(@NonNull DataspaceEntity dataspaceEntity, @NonNull AnchorEntity anchorEntity) { return findRootsByDataspaceAndAnchor(dataspaceEntity.getId(), anchorEntity.getId()).stream().findFirst() .orElseThrow(() -> new DataNodeNotFoundException(dataspaceEntity.getName(), anchorEntity.getName()));
Analysis of Get a Node API
Currently after multiple data trees are stored in CPS DB. On performing the GET operation on the same data, with xpath set as root "/", the first data tree is returned by the CPS-Core Get Data Node API. This data tree is returned in form of a JSON Object as follows:
After the GET API is updated, we want all the data trees to be returned when the xpath is set to root "/" and when a specific xpath is provided we want the functionality to remain as is. Now, when the xpath is set as root, CPS should return all the data trees. Now there are two possible responses we can get here:
Impact on CPS-NCMP_DMI plugin
The CPS NCMP DMI plugin internally calls the getDataNode method in order to fetch the configuration data for NCMP-DMI plugin, As of now it expects only a single DataNode to be returned by the getDataNode method and with the updated GET API we are now getting a collection of one or more data nodes from the getDtaNode method.
A couple of things to be checked here are:
- Will there be any Impact of multiple data nodes on the functionality of NCMP plugin
- Appropriate approach to bring in support for multiple data nodes into NCMP
The error was noticed in the following files, where the getDataNode method is being called internally:
Java file cps-ncmp-service/src/main/java/org/onap/cps/ncmp/api/inventory/InventoryPersistenceImpl.java Corresponding test cases cps-ncmp-service/src/test/groovy/org/onap/cps/ncmp/api/inventory/InventoryPersistenceImplSpec.groovy