frodovdr/node-red
1
0
Fork 0
mirror of https://github.com/node-red/node-red.git synced 2023-10-10 13:36:53 +02:00
Code Issues Releases Wiki Activity

Created Design: Dynamic MQTT node (markdown)

Nick O'Leary 2019-01-10 12:58:10 +00:00
parent db02c2cb56
commit ff8f122303
1 changed files with 29 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
Design:-Dynamic-MQTT-node.md Normal file

@ -0,0 +1,29 @@
There is a requirement for the MQTT nodes to allow for more dynamic configuration. There are two uses:
- determine a subscription topic at runtime
- modify broker connection details at runtime
This design note proposes a new MQTT node that can be used to satisfy these requirements.
---
Here's the basic outline:
- A new MQTT node is proposed called `mqtt-control` (name, as ever, subject to change).
- The node has an input and an output so sits in the middle of a flow
- The node is configured with an `mqtt-broker` node - this broker node provides the connection used by the control node.
- The node can be passed messages with a well-defined property (eg `msg.mqttControl`) that causes it to take an action.
- The actions the node can take are:
- Connect to its broker (with any of the `mqtt-broker` node's properties overridden by properties in the message)
- Disconnect from the broker
- Subscribe to a topic
- Unsubscribe from a topic
- Publish a message to a topic
- The node will send any message it receives due to its subscriptions.
- It will also pass through messages it receives when the action is complete. **TODO**: identify how to distinguish these from subscription messages
Some observations from this design:
- the control node is controlling the `mqtt-broker` node. Other regular nodes can also use that `mqtt-broker` node so will also be effected by changes.
- the `mqtt-broker` config node will have a new option to not auto-connect. This would be used where the decision to connect is left to the application's use of the control node.