[jdom-interest] Imcompatibility with GPL

Jason Hunter jhunter at servlets.com
Fri Sep 29 11:15:14 PDT 2006

Elliotte Harold wrote:
> Tatu Saloranta wrote:
> interested in links to thorough debunking.
>> 2 years ago (when I was trying to figure out whether
>> there could be incompatibility) all I found was
>> pervasive repetition of the story about an FSF lawyer
>> thoroughly confirming the incompatibility. ;-/
> See
> http://www.gnu.org/licenses/lgpl-java.html
> That's the lawyer you're talking about.

Thanks for the link.  In *my* opinion, his opinion isn't in any fashion 
authoritative on the question.  In fact, because he's a lawyer for the 
FSF he has more bias on the issue than I'd myself want if I was looking 
for legal advice on the topic.

Michael Kay wrote:
 > It's interesting to read that again. He claims that the "link" is
 > established by virtue of importing classes in a JAR file at compile time.
 > This would imply that if component A accesses component B via interfaces
 > defined in C, then there is no link between A and B, and A is not a
 > derivative work of B. For example, there is no link between a Saxon
 > application and Saxon if the application uses Saxon only via JAXP
 > interfaces.

Yes, this part strikes me as not understanding how Java works:

'Applications use Java's "import" functionality to access classes from 
these libraries. When the application is compiled, function signatures 
are checked against the library, creating a link. The application is a 
then generally a derivative work of the library.'

Java's import functionality?  OK, so what if I don't do any imports and 
use fully qualified class names everywhere?  Or what if I use reflection 
using Class.forName() to pull in classes and avoid any compile-time 
checking but still manage to make the calls?

Fact is the LGPL was written with C in mind, and because of that fact 
it's "squishy" when it comes to Java or any language that does runtime 
linking.  There's no legal precedent one way or the other.  Ask ten 
lawyers, get ten opinions.  When it comes to my own legal liability, I 
try to avoid squishy.  So thus I try to avoid using LGPL Java libraries 
in commercially redistributed projects as much as I can (internal use is 
fine, no license risk).


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