Notifying LWM2M server periodically with data from client

[Karandev]

How do we update the LWM2M server about a change in some sensor value, for example temperature value obtained from device sensors, in the form of endpoints and resources?

[szysas]

There are two things:

1. Make a resource to be observable (for example https://github.com/ARMmbed/java-coap/blob/master/coap-core/src/test/java/com/mbed/coap/observe/SimpleObservableResourceTest.java#L52)

2. Subscribe to a resource from RestAPI: https://docs.mbed.com/docs/mbed-device-connector-web-interfaces/en/latest/api-reference/

[Karandev]

If the value of an observable resource changed from client and then we need to push that new value to mbed server what should be done? This we are trying to do once we receive sensor data after a period of every 15 seconds.
We are using like this:
if(startedCoapServer != null && registrationManager != null) { SimpleObservableResource obsResourceX = new SimpleObservableResource("/AndroidDevice/Gravity/X", startedCoapServer); try { obsResourceX.setBody(gravityData[0] + ""); } catch (CoapException e) { e.printStackTrace(); } SimpleObservableResource obsResourceY = new SimpleObservableResource("/AndroidDevice/Gravity/Y", startedCoapServer); try { obsResourceY.setBody(gravityData[1] + ""); } catch (CoapException e) { e.printStackTrace(); } SimpleObservableResource obsResourceZ = new SimpleObservableResource("/AndroidDevice/Gravity/Z", startedCoapServer); try { obsResourceZ.setBody(gravityData[2] + ""); } catch (CoapException e) { e.printStackTrace(); } startedCoapServer.addRequestHandler("/AndroidDevice/Gravity/X", obsResourceX); startedCoapServer.addRequestHandler("/AndroidDevice/Gravity/Y", obsResourceY); startedCoapServer.addRequestHandler("/AndroidDevice/Gravity/Z", obsResourceZ); registrationManager.register(); }
This don't seems to be correct. Please help.

[szysas]

What kind of problems do you get?

[Karandev]

After some time keeping the application idle, a 502 error is received, even though de-registration is not done.

[szysas]

Logs please.

[szysas]

Note also that I added observable resource to example-client: https://github.com/ARMmbed/java-coap/blob/dev/example-client/example-client/src/main/java/com/mbed/coap/example/DeviceEmulator.java#L85

[Karandev]

We are able to send data continously every 15 seconds. Is there any parameter we need to set so that this happens for atleast, let's say, 30 minutes or one hour, without any interruption?

[szysas]

Well, just set your scheduler to send notification as often as you need.

[Karandev]

We keep on sending the data every 15 sec. After about 10 minutes or so testing in the mbed server console, clicking the Test Api button keeps on trying to fetch the data for get resources, but with no result.
What could be wrong?
When does the onNoObservers method get called?

[szysas]

Could you attached device logs?

[Karandev]

Now we are using the endpoint name, server key etc. from the security.h file from mbed portal. Is there a way to programmatically create the security.h file or the required keys?
We found that same endpoint name and keystore cannot be used for multiple android devices.
Please help.

[szysas]

I'm sure there is a way to make a (bash) script that would do the job automatically. Any collaboration is more than welcome :).
Is original issue solved? If so could we close this ticket?