| Table of Contents |
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Issues and Decisions
| # | Issues | Notes | Decision | ||||
|---|---|---|---|---|---|---|---|
| 1 | do we need separate operation for list or can we support all variations using same solution without interface changes | Toine Siebelink Prefer single solution that address all scenarios (multiple containers or list entries) correctly without interface changes. | |||||
| 2 | Should all patch operations be part of single transaction | for now treat individual | |||||
| 3 | what to do with failures |
| |||||
| 4 | What if a new data node(list item/container)is sent in the patch? |
| Lukasz Rajewskibrought up the point where if a new item is sent in the update request then what will be the expected behavior of CPS. | ||||
| 5 | How will we match the data nodes? | For example there are 10 data nodes and update is done on data nodes at position 1,5 and 9. How will the data nodes be matched? Because the payload will have only the 1st 5th and 9th data node with updated values | Arne Chrestin raised the following concern. Need to figure out how the matching of data nodes will take place in this scenario | Exposing endpoint to clients might be vulnerable. | we can add a flag to enable/disable this feature in docker compose file. | 2 | now we are able to add more than one root nodes. can we update data fragments of more than one root nodes.
Initial findings
When trying to perform Patch operation on a list data node, wherein multiple list items are updated in one request. It is seen that only the top most item in the list gets updated where as the remaining list items remain as it is.
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Assuming the following data is in the database
| Code Block |
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{ "int:interface-A": { |
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"interface": [ |
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{ |
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"name": "Interface-A", |
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"address": "10.10.10.200", |
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"enabled": true, |
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"subnet-mask": "255.255.255.0" |
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}, |
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{ |
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"name": "Interface-B", |
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"address": "10.10.10.200", |
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"enabled": true, |
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"subnet-mask": "255.255.255.0" |
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} |
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] |
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} |
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} |
When performing update operation with xPath set as root
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on the list data node
| Code Block | ||||
|---|---|---|---|---|
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curl --location --request PATCH 'http://localhost:8080/cps/api/v1/dataspaces/testDataspace/anchors/sample/nodes?xpath=%2Finterface-A' --header 'Content-Type: application/json' --header 'Accept: application/json' --header 'Authorization: Basic Y3BzdXNlcjpjcHNyMGNrcyE=' --header 'Cookie: JSESSIONID=node01ejoiyh1brii5zx8z9mk2r39l1.node0' \ |
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--data '{ |
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"int:interface-A": { |
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"interface": [ |
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{ |
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"name": "Interface-A", |
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"address": "10.10.10.0", //value to be updated |
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"enabled": false, //value to be updated |
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"subnet-mask": "255.255.255.0" |
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}, |
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{ |
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"name": "Interface-B", |
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"address": "1.1.1.1", //value to be updated |
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"enabled": false, //value to be updated |
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"subnet-mask": "255.255.255.0" |
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} |
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] |
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} |
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}' |
Status 200 OK is returned, but on performing the Get operation it is noticed only the leaf nodes get first item in the list node gets updated and list node second one remains as it is.
| Code Block | ||||
|---|---|---|---|---|
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{ |
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"int:interface-A": { |
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"interface": [ |
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{ |
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"name": "Interface-A", |
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"address": "10.10.10.0", //changed value |
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"enabled": false, //changed value |
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"subnet-mask": "255.255.255.0" |
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}, |
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{ |
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"name": "Interface-B", |
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"address": "10.10.10.200", //unchanged value |
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"enabled": true, //unchanged value |
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"subnet-mask": "255.255.255.0" |
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} |
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] |
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} |
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} |
Impact of CPS-1526 on this issue
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So, if there is a list data node with multiple list items, and the user tries to update multiple list items at once as in the example above, the system now returns a 400 Bad Request, with the error message that the operation is unsupported because the user is basically updating multiple data nodes under a list, earlier this response was a 200 OK with a partial Patch operation taking place in the background.
Assuming the following data is in the DB
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.
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Updating multiple items in a list data node
| Code Block |
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curl --location --request PATCH 'http://localhost:8080/cps/api/v1/dataspaces/testDataspace/anchors/MultipleDataTree/nodes?xpath=%2Finterface-A&observed-timestamp=2021-03-21T00%3A10%3A34.030-0100' \
--header 'Content-Type: application/json' \
--header 'Accept: application/json' \
--header 'Authorization: Basic Y3BzdXNlcjpjcHNyMGNrcyE=' \
--header 'Cookie: JSESSIONID=node01oja2kuolgg6dtfvnzzqf4bwk0.node0' \
--data '{
"interface": [
{
"name": "Interface-A-2",
"address": "1.1.1.1", //value to be updated
"enabled": true, //value to be updated
"subnet-mask": "0.0.0.0"
},
{
"name": "Interface-A",
"address": "10.10.10.10", //value to be updated
"enabled": true, //value to be updated
"subnet-mask": "0.0.0.0"
}
]
}' |
Response received after CPS 1526
| Code Block | ||
|---|---|---|
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{
"status": "400 BAD_REQUEST",
"message": "Operation is not supported for multiple data nodes",
"details": "Number of data nodes present: 2"
} |
Possible Solutions to Updating multiple items
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- Iterate over top-level element in patch.
- match each top element element to target data
- execute each patch
- Transactional ?!
- test & demo for each scenario
- top level containers
- top level list elements
- list elements under same container
By having a new sub end point for Patch operation that specifically performs update on list data nodes
New sub endpoint: PATCH http://{IP}:{PORT}/cps/api/v1/dataspaces/{dataspace-name}/anchor/{anchor-name}/list-nodes?xpath
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