Re: [PATCH v4 01/10] Battery: Add Battery Service Gatt Client

Johan,
On 08/16/2012 03:44 PM, Johan Hedberg wrote:

Hi Chen,

On Thu, Aug 16, 2012, Chen Ganir wrote:

quoted

quoted

I don't think it's ok to pollute the Device interface or src/device.c
with profile-specific details. That should happen in profile-specific
plugins and interfaces. Since we're switching over to object manager
maybe an interface/property like this isn't needed at all? (even if it
would be needed the type should be array{object} and not array{string}

You are correct, the array should be object instead of string.
However, i fail to understand why the object manager prevents this
from getting accepted - do you have a time estimation when the
object manager should be active or available ?

By the time of our next release (as per the content under the BlueZ 5
section in our TODO file).

Is there anywhere some documentation or instructions how to adapt the 
API for the new object manager ? Is it backward compatible to what we 
have today ? Do we really hold back DBUS additions until we change the 
DBUS API ?

quoted

I prefer this way of putting the batteries below the device, since it
is obvious which battery belongs to each device.

I fully agree with this. It's not what I had an issue with. However, if
we really want to make this clear you could additionally have a "Device"
property for each battery object pointing back to the parent object.

I can do that, if it helps. Although it is not necessary, since the 
object path for a battery already contains the device objec path in it :
[variable prefix]/{hci0,..}/dev_XX_XX_XX_XX_XX_XX/BATT-NN-DDDD
Adding a device object path as a property will be redundant.

quoted

The other option i can think of is to have another interface
registered on the device object path:

Service		org.bluez
Interface	org.bluez.Batteries
Object path	[variable prefix]/{hci0,..}/dev_XX_XX_XX_XX_XX_XX

Methods	dict GetProperties()

		Returns all properties for the interface. See the
		Properties section for the available properties.

Signals		ProperyChanged(string name, variant value)

		This signal indicates a changed value of the given
		property.

Properties	array{object} Batteries [readonly]

		List of device battery object paths that represents the available
batteries on the remote devices.


Service		org.bluez
Interface	org.bluez.Battery
Object path	[variable prefix]/{hci0,..}/dev_XX_XX_XX_XX_XX_XX/BATT-NN-DDDD


Methods	dict GetProperties()

		Returns all properties for the interface. See the
		Properties section for the available properties.

Signals		PropertyChanged(string name, variant value)

		This signal indicates a changed value of the given
		property.

Properties	byte Level [readonly]

			Battery level (0-100).

Any other suggestion ?

That would work, although both of these interfaces are rather
light-weight in that they only contain a single property which begs the
question whether this is a bit over-kill.

I know. I believe so as well, but if you want to separate the 
interfaces, it is a must.

Another option is to do away with the per-battery object somehow and
expose all batteries through a single interface. I'm not so sure that's
a good idea though since it could prevent future extensibility of the
API and doesn't reuse the common tools we have for object-like
abstractions (which a battery certainly is).

If we do what you suggest, a battery name (namespace+descriptor) will be 
the property name, and the value should be the battery level. i'm not 
too comfortable with it, and it is different than what we used to do up 
until now.

So where do we go from here ?

Johan

-- 
BR,
Chen Ganir
Texas Instruments