In case of error (let's remove the two sources above twice):
```json
{"count":2,"method":"u","removed":0,"srcs":[{"msg":"attribute double_scalar not found (devicetest/device/1)","src":"test/device/1/double_scalar"},{"msg":"attribute long_scalar not found (devicetest/device/1)","src":"test/device/1/long_scalar"}]}
```
#### Read the saved configuration for a set of sources (method:"r")
This method can be useful to measure the time it takes to retrieve the configuration from the cache.
It can be compared with the time taken to query the Tango Database directly to get the same piece of