[Bluez-devel] (no subject)

[Bluez-devel] (no subject)

[Fabrizio Guglielmino]

Hi all,
I made a simple software to send small pictures to all bluetooth  
devices in range (it's used by a museum ).
This software is made in C using bluez api, I've used two bluetooth  
dongles : one to make periodic inquiry (not with HCI periodic inquiry  
command by with a loop) and the other to make sdp query looking for  
obex push service and sending image.
My requirement was to use this software in some embedded linux based  
computer so I chose to limit external library, I made all using  
pthread so there is an infinite thread for inquiries and one thread  
to handle every sdp query and relative connection when devices are  
discovered. I've discarded also using python or other scripting  
languages for the platfom limitations.

All works but I found it not so efficient, also with 6/7 devices it's  
really slow to identify and connect to devices, some times connection  
are unexpectedly closed and so on....

Is it my approch to the problem wrong or bluetooth protocol is not  
suitable for this type of use?

I'm using libs version 3.7-1 (on debian 4.0)

Many thanks
Fabrizio
  

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Re: [Bluez-devel] (no subject)

[jm]

Hi Fabrizio,

I think connection attempts (pscan procedure) are serialized by the dongle, =

so maybe you should do the sdp queries sequentially and create the thread
when the connection is ready. You can also try to reduce the page timeout =

with "hciconfig pageto" to discard soon devices not in range at connection
time.

Someone please correct me if I'm wrong.

Jos=E9 Miguel


> Hi all,
> I made a simple software to send small pictures to all bluetooth  =

> devices in range (it's used by a museum ).
> This software is made in C using bluez api, I've used two bluetooth  =

> dongles : one to make periodic inquiry (not with HCI periodic inquiry  =

> command by with a loop) and the other to make sdp query looking for  =

> obex push service and sending image.
> My requirement was to use this software in some embedded linux based  =

> computer so I chose to limit external library, I made all using  =

> pthread so there is an infinite thread for inquiries and one thread  =

> to handle every sdp query and relative connection when devices are  =

> discovered. I've discarded also using python or other scripting  =

> languages for the platfom limitations.
>
> All works but I found it not so efficient, also with 6/7 devices it's  =

> really slow to identify and connect to devices, some times connection  =

> are unexpectedly closed and so on....
>
> Is it my approch to the problem wrong or bluetooth protocol is not  =

> suitable for this type of use?
>
> I'm using libs version 3.7-1 (on debian 4.0)
>
> Many thanks
> Fabrizio
>   =

>
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> https://lists.sourceforge.net/lists/listinfo/bluez-devel
>
>   =



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Re: [Bluez-devel] (no subject)

[Fabrizio Guglielmino]

jm ha scritto:
> Hi Fabrizio,
>
> I think connection attempts (pscan procedure) are serialized by the dongl=
e, =

> so maybe you should do the sdp queries sequentially and create the thread
> when the connection is ready. You can also try to reduce the page timeout =

> with "hciconfig pageto" to discard soon devices not in range at connection
> time.
>
> Someone please correct me if I'm wrong.
>
> Jos=E9 Miguel
>
>
>   =

>> Hi all,
>> I made a simple software to send small pictures to all bluetooth  =

>> devices in range (it's used by a museum ).
>> This software is made in C using bluez api, I've used two bluetooth  =

>> dongles : one to make periodic inquiry (not with HCI periodic inquiry  =

>> command by with a loop) and the other to make sdp query looking for  =

>> obex push service and sending image.
>> My requirement was to use this software in some embedded linux based  =

>> computer so I chose to limit external library, I made all using  =

>> pthread so there is an infinite thread for inquiries and one thread  =

>> to handle every sdp query and relative connection when devices are  =

>> discovered. I've discarded also using python or other scripting  =

>> languages for the platfom limitations.
>>
>> All works but I found it not so efficient, also with 6/7 devices it's  =

>> really slow to identify and connect to devices, some times connection  =

>> are unexpectedly closed and so on....
>>
>> Is it my approch to the problem wrong or bluetooth protocol is not  =

>> suitable for this type of use?
>>
>> I'm using libs version 3.7-1 (on debian 4.0)
>>
>> Many thanks
>> Fabrizio
>>   =

>>
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>>
>>   =

>>     =

>
>
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>
>   =

Thanks for suggestions, as You can read in my response to Marcel sdp =

query are already serialized but I find useful the use
of "pageto" to discard devices out of range. I'm also avaluating using =

inquiry with RSSI for this.

Thanks
Fabrizio

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Re: [Bluez-devel] (no subject)

[Marcel Holtmann]

Hi Fabrizio,

if you wanna get any real attention on this mailing list, you better
fill in a subject. I tend to quickly delete messages without a subject.

> I made a simple software to send small pictures to all bluetooth  
> devices in range (it's used by a museum ).
> This software is made in C using bluez api, I've used two bluetooth  
> dongles : one to make periodic inquiry (not with HCI periodic inquiry  
> command by with a loop) and the other to make sdp query looking for  
> obex push service and sending image.
> My requirement was to use this software in some embedded linux based  
> computer so I chose to limit external library, I made all using  
> pthread so there is an infinite thread for inquiries and one thread  
> to handle every sdp query and relative connection when devices are  
> discovered. I've discarded also using python or other scripting  
> languages for the platfom limitations.
> 
> All works but I found it not so efficient, also with 6/7 devices it's  
> really slow to identify and connect to devices, some times connection  
> are unexpectedly closed and so on....

A lot of people tried to make this work and there are ways to make it
work as efficient as possible. However you need an understanding on how
the Bluetooth radio and baseband are working and what the limits are.
For example using one or two threads doesn't give anything useful. This
is the wrong approach to start with. No excuses. You are simply blocking
the baseband with your random attempts. It is also better to use
periodic inquiry or explicitly cancel an inquiry when you wanna page the
remote device for a SDP query. It also makes sense to use the class of
device to a pre-filter on remote devices that actually support object
transfer.

Run a "hcidump -X -V" during your scans and connect attempts and you see
the errors that will present themself when you try to page during an
inquiry. The kernel takes care of a lot of stuff, but it is not psychic.

> Is it my approch to the problem wrong or bluetooth protocol is not  
> suitable for this type of use?

Do you have any choice when it comes to communicate with mobile phones?

> I'm using libs version 3.7-1 (on debian 4.0)

The latest version is 3.22 :)

Regards

Marcel



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Re: [Bluez-devel] Scan and push images

[Fabrizio Guglielmino]

Marcel Holtmann ha scritto:
> Hi Fabrizio,
>
> if you wanna get any real attention on this mailing list, you better
> fill in a subject. I tend to quickly delete messages without a subject.
>
>   
>> I made a simple software to send small pictures to all bluetooth  
>> devices in range (it's used by a museum ).
>> This software is made in C using bluez api, I've used two bluetooth  
>> dongles : one to make periodic inquiry (not with HCI periodic inquiry  
>> command by with a loop) and the other to make sdp query looking for  
>> obex push service and sending image.
>> My requirement was to use this software in some embedded linux based  
>> computer so I chose to limit external library, I made all using  
>> pthread so there is an infinite thread for inquiries and one thread  
>> to handle every sdp query and relative connection when devices are  
>> discovered. I've discarded also using python or other scripting  
>> languages for the platfom limitations.
>>
>> All works but I found it not so efficient, also with 6/7 devices it's  
>> really slow to identify and connect to devices, some times connection  
>> are unexpectedly closed and so on....
>>     
>
> A lot of people tried to make this work and there are ways to make it
> work as efficient as possible. However you need an understanding on how
> the Bluetooth radio and baseband are working and what the limits are.
> For example using one or two threads doesn't give anything useful. This
> is the wrong approach to start with. No excuses. You are simply blocking
> the baseband with your random attempts. It is also better to use
> periodic inquiry or explicitly cancel an inquiry when you wanna page the
> remote device for a SDP query. It also makes sense to use the class of
> device to a pre-filter on remote devices that actually support object
> transfer.
>
> Run a "hcidump -X -V" during your scans and connect attempts and you see
> the errors that will present themself when you try to page during an
> inquiry. The kernel taIs it my approch to the problem wrong or bluetooth protocol is not  
> suitable for this type of use?
>   
>
> Do you have any choice when it comes to communicate with mobile phones?
>
>   
>> I'm using libs version 3.7-1 (on debian 4.0)
>>     
>
> The latest version is 3.22 :)
>
> Regards
>
> Marcel
>
>
>
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>   

Ok for the subject, excuse me.

I can't undertand "You are simply blocking the baseband with your random 
attempts", where are the random attemps?
One thread is dedicated to make inquiry, it bind on a specific local 
adapter and make an infinite loop of inquiry (with a parametric sleep on 
every iteration).

On the other side for every device discovered it's lauched a thread for 
these operations:
1) sdp query for OPUSH service (serialized with a mutex)
2) connection to eventually discovered RFCOMM channel of the object push 
service
3) push of the content (with my own working obex implementation)

I'd like to accept Your suggests but:
- If I use periodic inquiry I need obligatory dbus to  receive callback 
events?
- How can I perform pre-filter on remote devices that support object 
transfer if I've not discovered their servies?

About library version I known I'm a little outdated ;-) but I'm 
preparing a new working environment with latest version.

Many thanks
Fabrizio

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Re: [Bluez-devel] Scan and push images

[Marcel Holtmann]

Hi Fabrizio,

> Ok for the subject, excuse me.

and please inline response. Otherwise it is hard to follow.

> I can't undertand "You are simply blocking the baseband with your random 
> attempts", where are the random attemps?
> One thread is dedicated to make inquiry, it bind on a specific local 
> adapter and make an infinite loop of inquiry (with a parametric sleep on 
> every iteration).
> 
> On the other side for every device discovered it's lauched a thread for 
> these operations:
> 1) sdp query for OPUSH service (serialized with a mutex)
> 2) connection to eventually discovered RFCOMM channel of the object push 
> service
> 3) push of the content (with my own working obex implementation)

as long as you only have one adapter attached to your system, you have
attempts to run inquiry and paging at the same time. This is not working
out. You can only do one thing at a time.

> I'd like to accept Your suggests but:
> - If I use periodic inquiry I need obligatory dbus to  receive callback 
> events?

You can do it by hand on a raw socket, but why would you? D-Bus gives it
to you nicely.

> - How can I perform pre-filter on remote devices that support object 
> transfer if I've not discovered their servies?

Check the Bluetooth specification. Every inquiry result contains a 3
byte class of device value.

Regards

Marcel



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Re: [Bluez-devel] Scan and push images

[Fabrizio Guglielmino]

Marcel Holtmann ha scritto:
> Hi Fabrizio,
>
>   
>> Ok for the subject, excuse me.
>>     
>
> and please inline response. Otherwise it is hard to follow.
>
>   
>> I can't undertand "You are simply blocking the baseband with your random 
>> attempts", where are the random attemps?
>> One thread is dedicated to make inquiry, it bind on a specific local 
>> adapter and make an infinite loop of inquiry (with a parametric sleep on 
>> every iteration).
>>
>> On the other side for every device discovered it's lauched a thread for 
>> these operations:
>> 1) sdp query for OPUSH service (serialized with a mutex)
>> 2) connection to eventually discovered RFCOMM channel of the object push 
>> service
>> 3) push of the content (with my own working obex implementation)
>>     
>
> as long as you only have one adapter attached to your system, you have
> attempts to run inquiry and paging at the same time. This is not working
> out. You can only do one thing at a time.
>   
Yes but I'm using two adapters so It's not a problem...
>   
>> I'd like to accept Your suggests but:
>> - If I use periodic inquiry I need obligatory dbus to  receive callback 
>> events?
>>     
>
> You can do it by hand on a raw socket, but why would you? D-Bus gives it
> to you nicely.
>   
Ok, I've to look about using dbus in plain C because I don't want to use 
Glib.
>   
>> - How can I perform pre-filter on remote devices that support object 
>> transfer if I've not discovered their servies?
>>     
>
> Check the Bluetooth specification. Every inquiry result contains a 3
> byte class of device value.
>
> Regards
>
> Marcel
>
>   
Yes I'known but the class isn't sufficient to known if remote device has 
an obex push service, sure can I remove all classes
that certainly  did not have this service but it's a form of 
optimization rather than a solution to the problem.

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>
>   



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Re: [Bluez-devel] Scan and push images

[Marcel Holtmann]

Hi Fabrizio,

> > as long as you only have one adapter attached to your system, you have
> > attempts to run inquiry and paging at the same time. This is not working
> > out. You can only do one thing at a time.
> >   
> Yes but I'm using two adapters so It's not a problem...

important information that you failed to mention. Two threads doesn't
automatically mean two adatpers.

> Yes I'known but the class isn't sufficient to known if remote device
> has 
> an obex push service, sure can I remove all classes
> that certainly  did not have this service but it's a form of 
> optimization rather than a solution to the problem.

Actually all device supporting OBEX Push should set the object transfer
service class. So you have to see if you also wanna support broken
devices or if profile compliant devices are enough.

Regards

Marcel



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Re: [Bluez-devel] Scan and push images

[Fabrizio Guglielmino]

Marcel Holtmann ha scritto:
> Hi Fabrizio,
>
>   
>>> as long as you only have one adapter attached to your system, you have
>>> attempts to run inquiry and paging at the same time. This is not working
>>> out. You can only do one thing at a time.
>>>   
>>>       
>> Yes but I'm using two adapters so It's not a problem...
>>     
>
> important information that you failed to mention. Two threads doesn't
> automatically mean two adatpers.
>
>   
In first mail I wrote : "...I've used two bluetooth dongles ...".
>> Yes I'known but the class isn't sufficient to known if remote device
>> has 
>> an obex push service, sure can I remove all classes
>> that certainly  did not have this service but it's a form of 
>> optimization rather than a solution to the problem.
>>     
>
> Actually all device supporting OBEX Push should set the object transfer
> service class. So you have to see if you also wanna support broken
> devices or if profile compliant devices are enough.
>
> Regards
>
> Marcel
>
>
>   
This is an important information I didn't known many thanks.
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>
>   



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Re: [Bluez-devel] Scan and push images

[Manuel Naranjo]

Fabrizio,
> I'd like to accept Your suggests but:
> - If I use periodic inquiry I need obligatory dbus to  receive callback 
> events?
> - How can I perform pre-filter on remote devices that support object 
> transfer if I've not discovered their servies?
>   
Check this project: http://code.google.com/p/proximitymarketing/ the
idea was to make an open source proximity marketing solution. Check in
the svn there's a proximity scanner (it uses dbus to scan for devices,
and does name resolving under requests, you need to change the functions
callbacks). It uses dbus bindings, and it's written in C.

I will make the official announcement for the project as soon as I
finish with my examns.

Cheers,
Manuel

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Re: [Bluez-devel] Scan and push images

[Fabrizio Guglielmino]

Manuel Naranjo ha scritto:
> Fabrizio,
>   
>> I'd like to accept Your suggests but:
>> - If I use periodic inquiry I need obligatory dbus to  receive callback 
>> events?
>> - How can I perform pre-filter on remote devices that support object 
>> transfer if I've not discovered their servies?
>>   
>>     
> Check this project: http://code.google.com/p/proximitymarketing/ the
> idea was to make an open source proximity marketing solution. Check in
> the svn there's a proximity scanner (it uses dbus to scan for devices,
> and does name resolving under requests, you need to change the functions
> callbacks). It uses dbus bindings, and it's written in C.
>
> I will make the official announcement for the project as soon as I
> finish with my examns.
>
> Cheers,
> Manuel
>
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>
>   
Many thanks...really useful.
Fabrizio


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