#Overview
This project provides a REST interface to execute queries on the databuffer.
Requirements
This project requires Java 8 or greater.
Deployment
Use the instructions provided by ch.psi.daq.install to install the application on a server.
Application Properties
Following files define and describe application properties:
- Cassandra specific properties.
- Query specific properties..
- Query REST specific properties.
It is possible to overwrite properties by defining new values in ${HOME}/.config/daq/queryrest.properties
REST Interface
Query Channel Names
Request
POST http://<host>:<port>/channels
Data
{"regex": "TRFCA|TRFCB", "dbMode": "databuffer"}
Explanation
- regex: Reqular expression used to filter channel names (default: no filtering). Filtering is done using JAVA's Pattern, more precisely Matcher.find()).
- dbMode: Defines the database to access (values: databuffer|archiverappliance)
Example
curl -H "Content-Type: application/json" -X POST -d '{"regex": "TRFCA|TRFCB"}' http://sf-nube-14.psi.ch:8080/channels
Query Data
Request
GET http://<host>:<port>/query
Data
A request is performed using JSON. The JSON query defines the channels to be queried, the range, and how the data should be aggregated (this is optional but highly recommended).
There exist following fields:
- channels: Array of channel names to be queried.
- startPulseId and endPulseId : A pulse-id range request with start and end pulse-id.
- startMillis/[startNanos] and endMillis/[endNanos]: A time range request with start and end milliseconds since January 1, 1970 (the UNIX/JAVA epoch) and optionally supplemented with the nanosecond offset to the milliseconds (range [0..999999]).
- startDate/[startNanos] and endDate/[endNanos]: A time range request with start and end date (format yyyy/MM/dd HH:mm:ss.SSS or dd.MM.yyyy HH:mm:ss.SSS) and optionally supplemented with the nanosecond offset to the milliseconds (range [0..999999]).
- ordering: The ordering of the data (see here for possible values).
- fields: The requested fields (see here for possible values).
- nrOfBins: Activates data binning. Specifies the number of bins the pulse/time range should be devided into.
- binSize: Activates data binning. Specifies the number of pulses per bin for pulse-range queries or the number of milliseconds per bin for time-range queries.
- aggregations: Activates data aggregation. Array of requested aggregations (see here for possible values). These values will be added to the data array response.
- aggregationType: Specifies the type of aggregation (see here). The default type is value aggregation (e.g., sum([1,2,3])=6). Alternatively, it is possible to define index aggregation for multiple arrays in combination with binning (e.g., sum([1,2,3], [3,2,1]) = [4,4,4]).
- aggregateChannels: Specifies whether the data of the requested channels should be combined together using the defined aggregation (values: true|false)
Example
curl -H "Content-Type: application/json" -X GET -d '{"channels":["channel1","channel2"],"startPulseId":0,"endPulseId":4}' http://sf-nube-14.psi.ch:8080/channels
Response example
The response is in JSON.
[
{
"channel":"channel1",
"data":[
{
"pulseId":0,
"iocMillis":0,
"iocNanos":0,
"globalMillis":0,
"globalNanos":0,
"value":0
},
{
"pulseId":2,
"iocMillis":2,
"iocNanos":2,
"globalMillis":2,
"globalNanos":2,
"value":2
},
{
"pulseId":4,
"iocMillis":4,
"iocNanos":4,
"globalMillis":4,
"globalNanos":4,
"value":4
}
]
},
{
"channel":"channel2",
"data":[
{
"pulseId":1,
"iocMillis":1,
"iocNanos":1,
"globalMillis":1,
"globalNanos":1,
"value":1
},
{
"pulseId":3,
"iocMillis":3,
"iocNanos":3,
"globalMillis":3,
"globalNanos":3,
"value":3
}
]
}
]
Example JSON Queries
TODO: