Device MQTT - Multi-Level Topics

In multi-level topics, the data in the published payload is the reading data. The names of the device and source are embedded into the topic. There are two ways multi-level topics are supported - async data and commands.

Async Data

Asynchronous data is published to the topic incoming/data/{device-name}/{source-name} where:

device-name is the name of the device sending the reading(s)
source-name is the command or resource name for the published data
In the case where the source-name matches a command name, the published data must be a JSON object with the resource names specified in the command as field names.
Example async published command data

Topic = incoming/data/MQTT-test-device/allValues
```
{
  "randfloat32" : 3.32,
  "randfloat64" : 5.54,
  "message"     : "Hi World"
}
```
In the case where the source-name only matches a resource name, the published data can either be just the reading value for the resource or a JSON object with the resource name as the field name.
Example async published resource data

Topic = incoming/data/MQTT-test-device/randfloat32
```
5.67
```
or
```
{
"randfloat32" : 5.67
}
```

Commanding

Commands sent to the device will be sent on the topic command/{device-name}/{command-name}/{method}/{uuid} where:

device-name is the name of the device that will receive the command
command-name is the name of the command being sent to the device
method is the type of command, either get or set
uuid is the unique identifier for the command request

Set Command

If the command method is a set, then the published payload contains a JSON object with the resource names and the values to set those resources. In response, the device is expected to publish an empty response on the topic command/response/{uuid} where the uuid matches the unique identifier sent in the command request topic.

Example - Set Command

Publish Topic = command/MQTT-test-device/randfloats/set/123 Publish Payload

{
  "randfloat32" : 3.32,
  "randfloat64" : 5.54
}

Response Topic = command/response/123 Response Payload = {}

Get Command

If the command method is a get, then the published payload is empty and the device is expected to publish a response to the topic `command/response/{uuid} where the uuid is the unique identifier sent in the command request topic. The published payload contains a JSON object with the resource names for the specified command and their values.

Example - Set Command

Publish Topic = command/MQTT-test-device/randfloats/set/123 Publish Payload: {} Response Topic = command/response/123 Response Payload

{
  "randfloat32" : 3.32,
  "randfloat64" : 5.54,
  "message"     : "Hi World"
}