CPS-251 - Getting issue details... STATUS
Overview
CPS temporal data query allows the user to fetch data based on multiple filtering criteria. This data can be used by an analytical system to take decisions.
Filtering Criteria
As it is time-series data, it can be filtered based on three main criteria:
Datetime
- Data after specified DateTime (To be supported in Istanbul Release)
- Data before specified DateTime
- Last X records
DataTypes in CPS Core
Dataspace & schema-set (To be supported in Istanbul Release)
- Dataspace & anchor (To be supported in Istanbul Release)
- Dataspace & multiple anchors - To improve performance, if there is a need to fetch data for multiple anchors.
Payload (To be partially supported in Istanbul Release)
Based on a field in the payload. These criteria need schema-set to be fixed to search in the same set of anchors. The details of the format are defined here.
We will implement only the basic APIs first and will add complex ones when required.
Other Parameters
There are other parameters, listed below, that can have an impact on the response.
| No | Name | Type | Default | Purpose | Example |
|---|---|---|---|---|---|
| 1 | page | int | 0 | The query output can have many rows so it is important to limit the fetched data. To limit the number of records and to provide pagination, these two parameters can be used. "page" parameter represents the page number, starts with 0, and "limit" is the page size. | |
| 2 | limit | int | 1000 | ||
| 3 | pointInTime | Timestamp (ISO Format) | CurrentDateTime | When a user uses the APIs with pagination (by running several stateless requests), the result set can be impacted by new states stored while navigating. This can be a challenge to retrieve a consistent result set. This parameter must be used to avoid this issue. However, It will not provide a consistent result set if data, that meet search criteria, get deleted because of the cleanup triggered by the retention policy. | |
| 4 | sort | string | timestamp:desc | Data is by default returned sorted by the timestamp in descending order. It can be overridden and data can be sorted by multiple fields. | sort=timestamp:asc,anchor:desc |
Assumptions
- Temporal database stores full information in the payload (CPS-192: Design data store for Temporal Service).
- Data in the response body will always contain the entire payload data.
Payload Filter Format
The data can be filtered, using JSON format, on one field at any level, but it is important to provide the entire path from the root. The below JSON is used as an example to explain the filtering format
The filtering scenarios and the format are defined below:
| No | Filter Condition | To be search | Format |
|---|---|---|---|
| 1 | Top-level Field | idNearRTRIC | { "idNearRTRIC": "1"} |
| 2 | Nested Field | nestedObject → id | { "nestedObject" : {"attributes" : {"gNBDUId": 4.0 }} } |
| 3 | Value(s) in a collection | labels | { "labels": ["cps"] } |
| 4 | Field of an object inside a collection | GNBDUFunction → idGNBDUFunction | { "GNBDUFunction" : [ {"idGNBDUFunction" : 5 }] } |
Proposed APIs
The GET Endpoints URI contains information about the anchors. But, the format of the anchor data is different in both CPS Core and CPS-temporal, which can cause some confusion. Hence, two endpoint format have been proposed.
The filtering criteria are passed as query parameter. The below mentioned query parameters are supported by all endpoints.
- after - timestamp ( ISO Format) to consider data created after the specified Timestamp
- simplePayloadFilter - to define payload filtering criteria
- page - to define the page number (required for pagination)
- limit - to limit the response size
- pointInTime - to consider data changed or added before this time.
- sort - to define the order of data in the result set
The response format for endpoints is the same and defined here
By Dataspace and Anchor
Endpoint Format A
URL: GET /dataspaces/{dataspace-name}/anchors/{anchor-name}
Example: GET /dataspaces/{dataspace-name}/anchors/{anchor-name}?after=2021-03-21T00:00:00-0:00&simplePayloadFilter={"idNearRTRIC":"1"}&limit=500
Endpoint Format B
URL: GET /dataspaces/{dataspace-name}/anchor-data?anchor={anchor-name}
Example: GET /dataspaces/{dataspace-name}/anchor-data?anchor={anchor-name}&after=2021-03-21T00:00:00-0:00&simplePayloadFilter={"idNearRTRIC":"1"}&limit=500
By Dataspace and Schema-set
Endpoint Format A
URL: GET /dataspaces/{dataspace-name}/anchors?schemaSet={schemaset-name}
Example: GET /dataspaces/{dataspace-name}/anchors?schemaSet={schemaset-name}&after=2021-03-21T00:00:00-0:00&simplePayloadFilter={"idNearRTRIC":"1"}
Endpoint Format B
URL: GET /dataspaces/{dataspace-name}/anchor-data?schemaSet={schemaset-name}
Example: GET /dataspaces/{dataspace-name}/anchor-data?schemaSet={schemaset-name}&after=2021-03-21T00:00:00-0:00&simplePayloadFilter={"idNearRTRIC":"1"}
Response
| name | type | |
|---|---|---|
| nextRecordsLink | string | added only if there are remaining records to be fetched for the query. |
| previousRecordsLink | string | added only if it is not the first set of records. |
| records | list | contains one record for each timestamp that meets filtering criteria. It contains header information along with data. |
{
"nextRecordsLink": "cps-temporal/api/v1/dataspaces/{dataspace-name}/anchors/{anchor-name}?after=2021-03-21T00:00:00-0:00&simplePayloadFilter={"idNearRTRIC":"1"}&limit=500&pointInTime=2021-04-21T00:00:00-0:00&page=2",
"previousRecordsLink": "cps-temporal/api/v1/dataspaces/{dataspace-name}/anchors/{anchor-name}?after=2021-03-21T00:00:00-0:00&simplePayloadFilter={"idNearRTRIC":"1"}&limit=500&pointInTime=2021-04-21T00:00:00-0:00&page=0",
"records": [
{
"timestamp": "2021-03-21T00:00:00-0:00",
"dataspace": "my-dataspace",
"schemaSet": "my-schema-set",
"anchor": "my-anchor",
"data": {
"status" : "UP"
}
}
]
}