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From Abid Hussain <>
Subject Re: using a dll in a webapp - Fixed!
Date Fri, 15 Dec 2006 14:55:57 GMT
Hi again,

I think I solved the problem.

Like I wrote, using
didn't work, neither did
CommDriver commDriver = (CommDriver) 

But initializing the driver using
Class clazz = 
CommDriver driver = (CommDriver) clazz.newInstance();
worked!! The driver did initialize correctly and the connection to the 
serial port was established!

Maybe the problem came up because Tomcat uses it's own classloader.

Now It is even not necessary anymore to set the java.library.path.

The win32com.dll is located in the WEB-INF/lib directory.

> 2 ways
> place the dll in jre\bin 
> add folder where win32com.dll is located to LD_LIBRARY_PATH in jvm.cfg?
> restart 
The reason why I didn't want to do so, is because I wanted all the 
needed stuff to be in the webapp directory, so that anyone can deploy 
the webapp remotely via the Tomcat-Manager and doesn't have to bother 
about setting path variables and doing other things on the machine where 
the server is running.

However, thanks a lot for helping me. I'm glad that it was easier than I 

Best regards,


> M-
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> ----- Original Message ----- 
> From: "Abid Hussain" <>
> To: <>
> Sent: Friday, December 15, 2006 9:03 AM
> Subject: using a dll in a webapp
>> Hi everybody,
>> I want to establish a connection to a serial port from my webapp by 
>> using the javax.comm package which uses the win32com.dll (on windows 
>> systems).
>> In most cases, it seems to be the common way to place the dll in the 
>> <jre>/bin directory. But I want to have all needed libraries in my 
>> webapp directory.
>> Therefore, I resolve the path of the dll in my webapp:
>> String win32com = new 
>> File(this.getClass().getClassLoader().getResource("win32com.dll").toURI()).getPath();
>> Now, I add the path to the java.library.path property:
>> System.setProperty("java.library.path", 
>> System.getProperty("java.library.path") + File.pathSeparator + win32com);
>> When I now output the java.library.path on the console (using 
>> System.getProperty("java.library.path")) the dll is in the path.
>> Now, I try to load the dll:
>> System.loadLibrary("win32com.dll");
>> And this fails. The Error message is:
>> java.lang.UnsatisfiedLinkError: no win32com.dll in java.library.path
>> I wonder how it's possible that the dll seems not to be in the 
>> java.library.path although I just added it - has anybody an idea?
>> Thanks a lot for helping.
>> Best regards,
>> Abid
>> -- 
>> Abid Hussain
>> Mail:
>> Web:
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Abid Hussain

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