Plans for hal 0.5.x
david at fubar.dk
Tue Dec 14 09:56:28 PST 2004
On Tue, 2004-12-14 at 19:03 +0300, Andrei Yurkevich wrote:
> > Well, since each connection method (USB, serial, bluetooth, etc) is
> > actually a hardware device itself, why not show the PDA as a _child_ of
> > that device? We are working with parent/child relationships as a
> > fundamental property of HAL already. Therefore you wouldn't necessarily
> > need a "pda.palm.serial_interface" property, you could just ask for the
> > "device.interface" (or something) property of the parent of the PDA
> > object.
> I am absolutely agreed with you about having a PDA device as a child
> node of the serial interface, but still I think that creating that node
> and filling it with pda-specific information should be done outside of
Again, the program doing this should run in the desktop session anyway
and already knows, so it needs not to tell hal about it.
> For that reason, HAL could just query the serial interface about
> what's on the other side and if that is PDA it could simply tag the
> serial interface. Then some callout or daemon that knows how to deal
> with different kinds of PDAs (or at leas that kind of PDA connected
> there) could create the PDA node below the serial port and set the
> necessary properties there.
You can't really probe a serial port since that may interfere with it's
operation. I don't think hal should attempt to do that, that's a can of
worms. E.g. if you really want to support legacy ports in your desktop
software, you need to take the painful route and do it from your desktop
sessions - e.g. the "Detect Modem" or "Detect PDA" button and then deal
with it. No such thing as a free lunch (reminds me; I should go to
> > It would seem like having that property on both the PDA _and_
> > the actual device itself would be redundant. (however, I can see it
> > being useful on the PDA so I'm not really objecting to having it there).
> In some cases, the fact that the serial port is there does not
> necessarily mean that PDA is available. For instance, when you plug in a
> Pocket PC PDA via USB, you will get a USB device and a USB-serial
> interface, but until you start the software that establishes a
> connection with your PDA you are not able to do anything useful with it.
No, but the fact that desktop software knows that there is a 100% chance
of the serial port having a PDA in the other end allows it to start
doing things with it. Like initiating a sync.
That's why I only think it's useful to consider plug and play devices.
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