Subcribe a channel / real-time notification - cumulocity

Question

Question about real-time notification..
Post: https://xxxiot.cumulocity.com/cep/realtime
Body:
[
{
"channel": "/meta/handshake",
"version": "1.0",
"mininumVersion": "1.0beta",
"supportedConnectionTypes": ["long-polling","callback-polling"],
"advice":{"timeout":120000,"interval":30000}
}
]
My Response:
[
{
"minimumVersion": "1.0",
"supportedConnectionTypes": [
"smartrest-long-polling",
"long-polling"
],
"successful": true,
"channel": "/meta/handshake",
"ext": {
"ack": true
},
"clientId": "5o0ghvle7yy4ix41on423v6k3j87",
"version": "1.0"
}
]
After received the clientId.. I have run the following command:
Post: https://xxxiot.cumulocity.com/cep/realtime
Body:
[
{
"channel": "/meta/subscribe",
"clientId": "5o0ghvle7yy4ix41on423v6k3j87",
"subscription": "/alarms/overHeatAlarms"
}
]
Response:
[
{
"error": "403:denied_by_security_policy:create_denied",
"subscription": "/alarms/overHeatAlarms",
"successful": false,
"channel": "/meta/subscribe"
}
]
Where is the problem? I'm trying to subcribing to "overheatAlarms"!
It may be that it does not exist? Can I read the existing information?
Thanks,
Alim

Answer 1

Yes, your suspicion is correct. There are basically two options for you:
Subscribe to all alarms or alarms from a particular device: Use "/cep/realtime" and channel "/alarms/* resp. channel "/alarms/[device ID]".
Create a processing rule that filters out overheat alarms and subscribe to that rule: Use "/cep/notifications" and channel "/[module name]/[statement name]".
The module name is what you enter as name when you click "New module". The statement name is what you add to the statement, e.g.
#Name('overHeatAlarms')
select * from AlarmsCreated where [your condition for overheat alarms]
(If you don't put a name there, they will be name statement_1, statement_2, ....)
To get notifications from Java, have a look at an example of getting notifications for changes in devices. In the subscribe() method, you pass "*" or the device ID. To get the notification, pass an implementation of SubscriptionListener, in particular the onNotification method. You can modify "channelPrefix" to "/alarms/" or "/measurements/" to get other notifications.

Answer 2

Thanks, André.
I've tested following Code Snippet.. it works, but it is not the best solution :-)
MeasurementApi measurementApi = getMeasurementApi();
MeasurementFilter measurementFilter = new MeasurementFilter();
while (true) {
Calendar cal = Calendar.getInstance();
Date toDate = cal.getTime();
cal.add(Calendar.SECOND, -25);
Date fromDate = cal.getTime();
measurementFilter.byDate(fromDate, toDate);
measurementFilter.byFragmentType(TemperatureMeasurement.class);
measurementFilter.bySource(new GId(DEVICE_SIMULATOR));
MeasurementCollection mc = measurementApi
.getMeasurementsByFilter(measurementFilter);
MeasurementCollectionRepresentation measurements = mc.get();
for (; measurements != null; measurements = mc
.getNextPage(measurements)) {
for (MeasurementRepresentation measurement : measurements
.getMeasurements()) {
TemperatureMeasurement temperatureSensor = measurement
.get(TemperatureMeasurement.class);
System.out.println(measurement.getSource().getId() + " "
+ measurement.getTime()+ " " + temperatureSensor.getTemperature() );
}
}
}