[Protocol Enhancement] Support for discovery of MQTT based devices in local network

[suresh-lc]

Is your feature request related to a problem? Please describe.
Currently only REST based devices can be discovered in Home Edge framework. Hence services provided by those devices are only discoverable. Devices supporting other protocols like MQTT are not discoverable in this.

Describe the solution you'd like
Method to discover MQTT based devices by adding support of MQTT (running a broker). This should support

Device discovery
Topic subscription/publish

Additional context
There are various considerations to be made during this process.

1. Currently Home Edge is Peer-Peer, meaning every device talks to every other device. So in similar regards should MQTT broker be running in all devices to maintain the current topology. So all device publish and subscribe to all other devices.
2. Should we run broker only in one device and all other device publish to it. Say device A runs the broker and device B ad C are client. Need to see how to exchange the capabilities of B and C with each other.
3. In case of single broker, broker selection method and fallback mechanism to be thought of.
4. Home Edge maintains the devices discovered by REST separately. And MQTT would be maintaining it separately. We need to either unify or refer both the dbs.
5. How do we expose services offered by MQTT devices , might be custom topics.
6. Identify MQTT library for adopting, probably 'mosquitto'.

[tiokim]

MQTT support is a very good idea in terms of extending the network topology.

[MoonkiHong]

@suresh-lc Thanks for the head-up. Seems good. What about contributing your idea to implement the MQTT client/broker to our project first? 😁

[NiranjanPatil25]

LF Home Edge – MQTT Plans : following are the 2 aspects , which one are we prioritizing to be done by Dec & which one to take in Y22
1 - LF Home Edge Even sync with Cloud
a. Current approach : EdgeX Integrated
b. New approach : Sync events with cloud (AWS/Azure/G ) Independent of EdgeX

2- Local MQTT
a. Discovery : discover local MQTT devices
b. Control : control the MQTT devices locally eg SWITCH ON AC
c. Eventing : Local event exchange eg : AC sends its current state event to Broker ,

[tiokim]

LF Home Edge – MQTT Plans : following are the 2 aspects , which one are we prioritizing to be done by Dec & which one to take in Y22 1 - LF Home Edge Even sync with Cloud a. Current approach : EdgeX Integrated b. New approach : Sync events with cloud (AWS/Azure/G ) Independent of EdgeX

2- Local MQTT a. Discovery : discover local MQTT devices b. Control : control the MQTT devices locally eg SWITCH ON AC c. Eventing : Local event exchange eg : AC sends its current state event to Broker ,

It would be great if the cloud synchronization feature without edgex could be done this year. 😄

[suresh-lc]

LF Home Edge – MQTT Plans : following are the 2 aspects , which one are we prioritizing to be done by Dec & which one to take in Y22 1 - LF Home Edge Even sync with Cloud a. Current approach : EdgeX Integrated b. New approach : Sync events with cloud (AWS/Azure/G ) Independent of EdgeX
2- Local MQTT a. Discovery : discover local MQTT devices b. Control : control the MQTT devices locally eg SWITCH ON AC c. Eventing : Local event exchange eg : AC sends its current state event to Broker ,

It would be great if the cloud synchronization feature without edgex could be done this year. 😄

Cloud synchronization can be done with HTTP or MQTT. So here we say by Cloud Synchronization using MQTT method where in the MQTT broker would be running at cloud and edge devices would send data to this MQTT endpoints.

Device meta data and device generated data are two aspects which can by synch.

Currently we provide APIs to store data. So we need to provide API to developer to send data to cloud. Internally first the device details (device twin kind) should also be made in cloud to hold the data might be.

We should also identify one of the cloud vendor to start of with might be as first step.

[MoonkiHong]

@suresh-lc Let us separate the topic into 2.

1. Cloud synchronization through MQTT (Yes, it can be done through HTTP. 😅 But I believe that this is not a point of discussion)
2. Local MQTT discovery/control/and eventing: MQTT broker at cloud and edge.

As @NiranjanPatil25 pointed out, let us use this thread to take about item number 2 (Local MQTT), and let another (item number 1 - cloud synchronization through MQTT, but without EdgeX just in case) reside in an independent thread / issue.

[suresh-lc]

@suresh-lc Let us separate the topic into 2.

1. Cloud synchronization through MQTT (Yes, it can be done through HTTP. 😅 But I believe that this is not a point of discussion)
2. Local MQTT discovery/control/and eventing: MQTT broker at cloud and edge.

As @NiranjanPatil25 pointed out, let us use this thread to take about item number 2 (Local MQTT), and let another (item number 1 - cloud synchronization through MQTT, but independent to EdgeX0 in other issue.

Was just thinking the same . Might be we start using the #382