Hi Chen,
On 11/18/2011 9:28 PM, Chen Ganir wrote:
On Sat, Nov 19, 2011 at 01:39, Brian Gix<bgix@xxxxxxxxxxxxxx> wrote:
Those are otherwise good points (not all devices will automatically start
advertising again) however ServiceChanged should never be attempted to be
read. We should only obtain this via an Indication from the remote device,
and at any rate it is only shared with Trusted devices, so we would have to
be Bonded.
However, I would definitely NOT try to re-read Name/Appearance at every
connection. Those should definitely be cached, and not re-read unless we
get the ServiceChanged Indication.
ServiceChanged is irrelevant here. ServiceChanged will only notify you
if the handles changed, not if the value changed. Name and appearance
can and should be read, since we may get only the short name in the
advertising data, and we wil need the full name. In addition, a device
may change its name, and we will not be notified of this (GAP name
characteristic does not notify/indicate). Name may change just like it
does in BR/EDR.
I don't think we should do anything automatically on start-up.
If we know that we do not have the full name (if the Adv data has it
flagged as "Partial") then we should of course fetch the full name from
the characteristic. However, if we get in the habit of re-reading data
just because it *may* have changed, then we lose track of what LE is all
about, which is minimization of over-the-air traffic.
If a particular high level app wants refresh the Name and/or Appearance,
then of course which should provide that ability, but I might consider
that App to be poorly written barring a compelling need, like perhaps an
indication that it needs to be re-paired. Single mode LE devices will
generally be single mode because they want to limit these unneeded
transactions. LE Profiles are designed to not require Polling type
activities, which a Name or Appearance refresh would be.
--
Brian Gix
bgix@xxxxxxxxxxxxxx
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum
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