Multiple things per WebSocket

WebThingsIO / api

Web Thing API Specification

http://iot.mozilla.org/wot/

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Multiple things per WebSocket #46

Open bbangert opened 6 years ago

bbangert commented 6 years ago

When a websocket endpoint is acting as a gateway/adapter to many Web Things, it'd be ideal to have a single websocket connection to the gateway. This could be handled by including a URL in the message indicating what it went to, etc.

benfrancis commented 6 years ago

I agree it should be possible to have multiple things per WebSocket, as you say we just need to provide a thing ID (URI) in each message to indicate which thing it refers to.

YonasJ commented 5 years ago

I would like to bump this idea.

When implementing the API using the arduino API's for the ESP32 I have encountered some challenges:

The API's don't really support handling the websockets dynamically. So, it is a fair bit of extra coding to create an end point for each URL.
Each websocket uses a fair amount of the precious memory available.
I had to do a lot of duplication to support the HTTP and WebSocket API.

I will put some comments in "Implement a single Websocket endpoint for things #947" as well.

benfrancis commented 5 years ago

Proposal: Add an id field to WebSocket messages whose value is a URI identifying the thing the message relates to.

{
  "id": "http://mythingserver.com/things/robot1"
  "messageType": "setProperty",
  "data": {
    "leftMotor": 100
  }
}

We also need to figure out how to expose the WebSocket endpoint as currently we do this in the links member of a Thing resource which corresponds to a single Thing.

Perhaps if there is a Gateway capability the Thing Description for the gateway itself can have a top level links member which can link to a WebSocket endpoint for the whole gateway.

benfrancis commented 5 years ago

Note that the W3C spec already has an id member for a Thing which is a URI identifying the Thing. This can optionally be the URL of the Thing Description.

hobinjk commented 5 years ago

As per the meeting today, this should come with a section or equivalent note that opening a websocket on /things will make a websocket corresponding to multiple things.

This could be considered part of a Gateway capability