Device does not wait for a response even specifying hono-ttd=60

[Lando-Ant]

I am using Eclipse Hono and I am experiencing an issue with hono-ttd, that is, when I launch the HTTP POST command from the device to send telemetry data by specifying e.g. hono-ttd=60, the device does not wait to receive a command instead it continues its execution. Moreover, I have no idea where to found the hono-cmd-req-id that should be returned by the device receiving the command.

This is the command I used to send telemetry data from the device:
curl -i -u [email protected]:demo-secret -H 'application/json' --data-binary '{ "topic": "org.eclipse.packages.c2e/demo-device/things/twin/commands/modify", "headers": {}, "path": "/features/temperature/properties/value", "value": 45 }' http://${HTTP_ADAPTER_IP}:${HTTP_ADAPTER_PORT_HTTP}/telemetry?hono-ttd=60
After sending the above telemetry data, I expect the device to wait for a command. Instead, the device does not wait and immediately returns:
HTTP/1.1 200 OK hono-command: modify-response content-type: application/vnd.eclipse.ditto+json content-length: 361

Thanks in advance for helping out!

[sophokles73]

Your device already has received a (one-way) command from Ditto as indicated by the HTTP reponse's content-type application/vnd.eclipse.ditto+json. Ditto has sent this one-way command in response to your modify message. The HTTP response will only contain a hono-cmd-req-id header if an application sends a request-response command for which the application expects the device to send a response by means of POSTing to the HTTP adapter's /command/res/ resource (see https://www.eclipse.org/hono/docs/user-guide/http-adapter/#sending-a-response-to-a-command-authenticated-device).

If you want to see the device waiting for a command instead, you should send an empty-notifcation by means of POSTing an HTTP request with no payload to the HTTP adapter:

curl -XPOST -u [email protected]:demo-secret -H 'content-type: application/vnd.eclipse-hono-empty-notification' http://${HTTP_ADAPTER_IP}:${HTTP_ADAPTER_PORT_HTTP}/telemetry?hono-ttd=60

In this case, Ditto will not find any message to process and will therefore not send the one-way command acknowledging the modify message ...

[Lando-Ant]

Thank you @sophokles73, so how should I retrieve the hono-cmd-req-id?
The response should be something like this
`HTTP/1.1 200 OK
hono-command: start-watering
hono-cmd-req-id: 024d84b1ceb-797b-45f5-bc87-78e9b5396645replies
content-type: application/json
content-length: 516

{"topic":"org.eclipse.packages.c2e/demo-device/things/live/messages/start-watering","headers":{"correlation-id":"d84b1ceb-797b-45f5-bc87-78e9b5396645","x-forwarded-for":"10.244.0.1","version":2,"timeout":"0","x-forwarded-user":"ditto","accept":"/","x-real-ip":"10.244.0.1","x-ditto-dummy-auth":"nginx:ditto","host":"172.17.0.2:30385","content-type":"application/json","timestamp":"2020-02-28T08:04:43.518+01:00","user-agent":"curl/7.58.0"},"path":"/inbox/messages/start-watering","value":{"water-amount":"3liters"}}`
In which the hono-cmd-req-id appears too, but I only receive the response specified in my first comment.

[sophokles73]

My understanding is that you are trying to follow the tour of the e2e Eclipse IoT package tour.

So can you please describe what exactly you are doing on both the device side as well as in the back end? What request(s) you send to the Hono HTTP adapter and what requests to you send to the Ditto HTTP API?

[Lando-Ant]

Simply I run
minikube start --driver=virtualbox
And after waiting for all the pods to be up and running, I run the command I posted in the first comment from a terminal. I expected the hono-cmd-req-id to appear in the output but it does not.

[sophokles73]

@Lando-Ant is this still an issue?