Re: Device discovery for control/sensor schemas

["Mal Lansell" <mlansell@xxxxxxxxxxxxxx>]

--- In ukha_xpl@xxxxxxx, "John B" <home-automation@j...>
wrote:
> Hi all,
>
> Many of the recent xPL apps are making use of the sensor/control
schemas, as these make it much easier for devices to interoperate.
>
> However, there is no way of finding out a list of valid devices
that a particular xPL connector supports.
>
> If we take DMX as an example, we can send a message like:
>
> control.basic
> {
> device=3
> type=dmx
> current=255
> }
>
> This will set channel 3 to level 255.
> But how do we know what channel 3 actually is?
> Or even if channel 3 exists at all?
>

You can't.  Channel 3 will "exist" as far as a DMX transmitter is
concerned, but there is absolutely no way to tell if there is any
hardware plugged in that responds to channel 3.


> We should be able to be given a list of all known DMX channels, and
a friendly description of what is connected to them.
>
> The same issue applies to things like the C-Bus connector - you
shouldn't have to remember the C-Bus group address of the light(s)
you want to control - you should be able to be presented with a list
of all detected devices.
>
> The question is: Should each xPL connector be responsible for
maintaining a list of "friendly" device names, and mapping them
to
actual device names, so you'd be able to send something like:
>
> control.basic
> {
> device=lounge_lights
> type=dmx
> current=255
> }
>
> Or should it be up to a controller like xPLHal to store this
information and do the mapping between friendly devices and actual
devices?
>

I don't think it's xPLHal's business to store such information,
although it can help set it up.  Friendly device names should be
presented as config items - but whether they are editable will depend
on the device itself.

The mapping of name to hardware should be dealt with either by the
xPL connector or by the device, depending on the abilities of that
device.  The end result is the same - the connector/device combo
presents friendly names to the xPL world.

Take DMX as an example.  The channel names should be config items.
In xPLHal, we can edit those names to best represent the actual
device on the DMX network.  Scripts in xPLHal and messages sent to
the xPL-DMX application use those names.  The application translates
the name to the channel and sets the appropriate light level.

With more sophisticated hardware that uses such names already, the
xPL connector would handle presenting those names as config items to
xPLHal, and passing back any changes.

Mal