Cumulocity API to get timestamp

Question

Is there an API to get data based on timestamp? This would help to retrieve only the delta since the last API call from the Cumulocity.

Or, as alternative: Is there an API that can push data to an HTTP port or a messaging queue?

Answer 1

Both is possible. Time-series data such as events, alarms and measurements have "dateFrom" and "dateTo". For example, try

/measurement/measurements?source=101000&dateFrom=2015-07-19&dateTo=2015-07-20&pageSize=2000

(Replace "source" with your device ID and change dateFrom/dateTo accordingly.)

For operations, you get the delta automatically due to their state model. All new operations are in state "PENDING", and when you execute them on a device, you set them to "EXECUTING". This is described in the reference guide sections, e.g., https://cumulocity.com/guides/reference/measurements.

But if you really want to continuously get data out, I recommend using the pub/sub APIs. I.e. get all new events for a device by subscribing to the channel /events/[deviceId] on the URL /cep/realtime. The general protocol (cometd) is described here: https://cumulocity.com/guides/reference/real-time-notifications. The different channels and endpoints are described at the bottom of each API page. You can also create custom pub/sub channels through event processing rules if you want to do something entirely different.