2006-11-20 16:54:22

by Pierre-Yves Paulus

Subject: [Bluez-devel] Extracting full SDP database from device at once using DBus API

Hello,

At the moment, to perform a full extraction of the SDP database of a
device, I first perform a call to

array{uint32} GetRemoteServiceHandles(string address, string match)

with an empty "match" string. It does connect to Public Browse Group,
and returns handles for all the ServiceRecords. I then perform a call

array{byte} GetRemoteServiceRecord(string address, uint32 handle)

for each of these handles, and I get all the data in binary form ti
interpret myself.


1) Is it the right way to do this, or is there a way to get that all at
once?

2) As ServiceRecords are extracted "one at a time", is Bluez connecting
and disconnecting to the device each time? Is there a performance
penalty in doing so? If I understand the output of hcidump well, it does
not close he ACL link each time, but there is a L2CAP
connection/disconnection for each ServiceRecord.

Thanks a lot,
Best Regards

Pierre-Yves

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2006-11-21 09:58:38

by Pierre-Yves Paulus

Subject: Re: [Bluez-devel] Extracting full SDP database from device at once using DBus API

Hi Marcel,

Thanks a lot for your kind answer.

Pierre-Yves



Marcel Holtmann wrote:
> Hi Pierre-Yves,
>
>> At the moment, to perform a full extraction of the SDP database of a
>> device, I first perform a call to
>>
>> array{uint32} GetRemoteServiceHandles(string address, string match)
>>
>> with an empty "match" string. It does connect to Public Browse Group,
>> and returns handles for all the ServiceRecords. I then perform a call
>>
>> array{byte} GetRemoteServiceRecord(string address, uint32 handle)
>>
>> for each of these handles, and I get all the data in binary form ti
>> interpret myself.
>>
>>
>> 1) Is it the right way to do this, or is there a way to get that all at
>> once?
>
> that is the way to go.
>
>> 2) As ServiceRecords are extracted "one at a time", is Bluez connecting
>> and disconnecting to the device each time? Is there a performance
>> penalty in doing so? If I understand the output of hcidump well, it does
>> not close he ACL link each time, but there is a L2CAP
>> connection/disconnection for each ServiceRecord.
>
> We should add a disconnect timeout to our SDP session and re-use it, but
> that hasn't been done so far.
>
> Regards
>
> Marcel
>
>
>
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2006-11-20 17:03:26

by Marcel Holtmann

Subject: Re: [Bluez-devel] Extracting full SDP database from device at once using DBus API

Hi Pierre-Yves,

> At the moment, to perform a full extraction of the SDP database of a
> device, I first perform a call to
>
> array{uint32} GetRemoteServiceHandles(string address, string match)
>
> with an empty "match" string. It does connect to Public Browse Group,
> and returns handles for all the ServiceRecords. I then perform a call
>
> array{byte} GetRemoteServiceRecord(string address, uint32 handle)
>
> for each of these handles, and I get all the data in binary form ti
> interpret myself.
>
>
> 1) Is it the right way to do this, or is there a way to get that all at
> once?

that is the way to go.

> 2) As ServiceRecords are extracted "one at a time", is Bluez connecting
> and disconnecting to the device each time? Is there a performance
> penalty in doing so? If I understand the output of hcidump well, it does
> not close he ACL link each time, but there is a L2CAP
> connection/disconnection for each ServiceRecord.

We should add a disconnect timeout to our SDP session and re-use it, but
that hasn't been done so far.

Regards

Marcel



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