[Bluez-devel] Re: help with bluetooth on linux

[Gabriel Marques <gag@certi.org.br>]

First of all, thanks for answering my questions, but there was a 
misundertanding here.
And sorry if my questions created a Java vs. C battle.
Comments are in line:

Jean wrote:

>On Thu, May 12, 2005 at 04:02:50PM -0300, Gabriel Marques wrote:
>  
>
>>Hi, I've found your e-mail in a "how to" about "Brainboxes BlueTooth + 
>>Linux Howto".
>>The tutorial is helping a lot but I still got some problems, and I was 
>>hoping you could help me out with any information.
>>In my work (with JavaTV) I need to set up a communication channel over a 
>>BT device, using an open-source Java BT stack.
>>    
>>
>
>	That's typical of the Java people, they want to rewrite the
>whole OS in Java. This only lead to lot of duplicated code,
>interoperability problem and madness. Please use the OS existing BT
>stack, don't rewrite your own.
>  
>
Hehe, I'm not a Java addict who wants to rewrite the OS in java.
I'm writing applications for set-top boxes (DTV receivers), they only 
run Java (well, for the manufacturer they run RTLinux or something), and 
have no BT implementation.
The only return channel they provide is a phone modem, or sometimes 
something that the manufacturer implements, and a serial port, that is 
used for debugging and Java apps. loading.
Since I can't force the manufacturers to provide me a bluetooth return 
channel, but I can ask them to open acess to the serial port, the 
solution I found is to plug a serial BT dongle on it.
That implies in implementing the stack in Java. I totally agree that 
this is a task for C or even hardware to implement, but for business 
reasons, I have to validate some prototypes with BT so that maybe, 
someday, the Java API will be implemented in the OS.
Well, thats the future, for now, I have to make a Java BT stack talk to 
a serial BT device, implement some apps. over it, so that in sequence I 
can port it tho some set-tops.
Windows is way too restrictive to this phase of developing, so I'm using 
linux, but I can't send questions to the BlueZ forums, cause it's 
off-topic. (actually I already tried :) )

>	Let suppose your Java programe use a Java BT stack, and you
>want both your Java program and a regular C/C++ program (BT
>mouse/audio driver) to use BT, how do you make that work. You can't.
>
>  
>
That won't happen, the only apps. that will use the BT will be java 
ones, and once the Java API is valid, it wil probably be implemented by 
the set-top OS/hardware.

>>JavaBluetooth relies on a serial/tty abstraction of the HCI layer (H4), 
>>and works fine with serial (RS232) BT dongles.
>>But those are hard and expensive to find, and all I have is two USB 
>>dongles. One is a 3com and the other came from china.
>>Well, my problem is: *How to make JavaBluetooth work with an USB dongle*
>>    
>>
>
>	Don't. It's a waste of time.
>  
>
True, but what can I do, it comes with the package :)

>	The proper question is : how do I access in Java the existing
>BT stack of Linux that is fully debugged and fully functional.
>
>  
>
>>I've installed Fedora Linux (kernel 2.6.11-1.14_FC3), and the USB dongle 
>>was recognized automatically, its running fine trough BlueZ.
>>can you help me with some steps on putting the usb_bt>serial_bt driver 
>>to work?
>>    
>>
>
>	No, what you need to do is to create a JNI enabling your Java
>program to access the BlueZ APIs. The BlueZ APIs are all sockets of
>various types, and most likely you only need one or two types, so this
>is not as bad as it looks like. Yeah, it's a shame that writting JNI
>is so messy, SUN should improve that.
>	If you want an example of such JNI, you can look at the
>Java-IrDA API done be a collegue of mine. That's the right way to do
>it.
>	Actually, somebody might have already done that, so ask around...
>  
>
I've asked around a lot before asking to you, perhaps you can indicate 
some list or reference, like the IrDA one.
Thanks.

>	Regards,
>
>	Jean
>  
>
Oh, and I've sent the last message from a wrong e-mail, I'm still 
getting used to Thunderbird :)


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