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

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

[Pierre-Yves Paulus]

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

[Marcel Holtmann]

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

[Pierre-Yves Paulus]

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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