Help

Re: Help

Wael Khalil wrote:
> Hi guys
> I'm only a student
> I'm trying to connect two computers together using the usual USB cable 
> which ends with two male connectors on both sides
> so I cut the power wire within the cable
> and connected the two computers to their USB ports
> I used the jusb API for Windows and javax-usb to do that
> but java didn't recognize any device on any port even though I know that 
> the root hub
> is a device (isn't it)

> So I'm asking your help because I have to handle this project to my 
> supervisor in no time (Pleeeeeeeeeeeeeeease)
> 1- I want to ask you guys is it about the cable:
> I mean that did I ruin the cable when I cut the power wire in it?!!!
> Could it work if I didn't cut that wire (I thought that the ports might 
> be damaged or even the motherboard culd be damaged also) is my thought 
> right or not.

You should NOT connect the 2 computers with a home made cable, it will 
not work, and if the computers are on different potential levels you 
could get a power rush.

(Earlier I connected 2 ungrounded computers using a BNC cable, and you 
could actually see sparks going from from one of the computers to the 
shield of the cable before they connected and had a common ground via 
the cable shield.)

> Not e: There's a USB device in the market which can be used to connect 
> two windows systems together, I am not allowed to use it.

Too bad, that's probably the only way you could connect two computers 
using USB.

> 2- Or is the whole idea is wrong and I can't connect two PCs through usb 
> ports
> using Javax-usb?

Javax.usb is for communicating with the devices. With the special cables 
used to connect two computers there is actually a device in the middle 
which both computers (hosts) talks to.

> 3- Can I do this through USB hub?
>  
> If the answer is Yes I can connect the PCs by the help of Java over USB 
> ports
> please send me a solution (How to connect the PCs) and a code to begin with.
>  
> and if I can't do it please tell me why.

There are several technical reasons why this can not work, USb does not 
use a protocol with collision detection or some other kind of 
collaboration to get multiple devices to share a common cable. Instead 
there is a host (the computer) which tells each device when it can send 
data. Now, if you take 2 computers and connect them together they will 
both try to control the bus.

For more information of how this actually works I'd recommend reading 
the specifications at www.usb.org.

//Roger

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Thanks a lot

The version is :javax.usb.UsbException: Error while loading shared library libJavaxUsb.so : no JavaxUsb in java.library.path

Help Again

Re: The version is :javax.usb.UsbException: Error while loading shared library libJavaxUsb.so : no JavaxUsb in java.library.path

Please see the FAQ:
http://javax-usb.org/faq.html#linux_imp_jar_file

On Sat, 4 Mar 2006, Aravindakshan M R wrote:

>Hi everyone,
> 
>           I have downloaded the following  three packages :          
>                                  javax-usb_1.0.1.tar.bz2
>                                  javax-usb-ri-linux_1.0.1.tar.bz2
>                                 javax-usb-ri_1.0.1.tar.bz2
> And then build jar files using Ant. These jar files where were added to the classpath.Also the directory
containing the     javax.usb.properties was added to the classpath.
> The simple program that i am trying to run is below:
> 
> import java.util.*;
> import javax.usb.*;
> public class trial {
>     
>     /** Creates a new instance of trial */
> public static void main(String args[])
> {
> try
> {        
>    UsbServices servee=UsbHostManager.getUsbServices();
>   
> }
> catch(Exception e) { System.out.println("The version is :" +e);}
>     
> }
> }
> 
> The above program gets compiled but it doesnot run and gives the error message shown in the subject.
> Kindly help regarding this as quickly as possible.
> 
> Thank you
> Aravind
> 
>		
>---------------------------------
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> PhotoMail  - it's free and works with Yahoo! Mail.

--

-- 
Dan Streetman
ddstreet <at> ieee.org
---------------------
186,272 miles per second:
It isn't just a good idea, it's the law!

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