[Feature] Custom dbus Input/Output nodes with dynamic subscription capability

[dirkjanfaber]

The idea for the input node is analagous to the build-in node-red mqtt node set to "Dynamic Subscription" mode, but to access the dbus directly.

Dynamic Input Node:

Has an input and an output.

input accepts 2 message types

• subscribe:
  msg.topic: subscribe
msg.payload: {serviceName: <dbus service name>, path: <dbus path name>}
• unsubscribe:
  msg.topic: unsubscribe
msg.payload: {serviceName: <dbus service name>, path: <dbus path name>}

output emits values whenever a subscribed value on dbus updates, or when a new value is subscribed to like:

msg.topic: dbus-value
msg.payload: {serviceName: <dbus service name>, path: <dbus path name>, datatype: <datatype of dbus value>, value: <value on dbus>}

Dynamic Output Node

One input, able to write a value to any dbus path:

• msg.topic: write
msg.payload: {serviceName: <dbus service name>, path: <dbus path name>, datatype: <datatype of dbus value>, value: <value to write>}

[petermlyon]

Thanks @dirkjanfaber for opening this from the outcome of our discussion.

The suggestions made for the msg structure were only to exchange the idea so from my perspective they can be freely modified to something that makes more sense according to you guys.