what does constitute "linking"?

Janez Pers janez.pers at fe.uni-lj.si
Thu Jun 18 16:55:41 CEST 2009


Dear All,

I have a bit unortodox question. I cannot find any better
place to get an answer, if there is, please point me in
that direction.

The main question seems silly: does connecting the
proprietary application with the GPLed one constitutes
"linking" in terms of GPL license?

The straightforward answer would probably be no, right?

But, consider a following scenario:

1. I take the GPLed/LGPLed library "A" and "socketize" it -
meaning, I write the interface to the library that
provides its funcionality via TCP sockets.

2. I publish the source code to this interface as required
per GPL, as the new improved library clearly constitutes
derived work.

3. I write my (proprietary) application "B" in a way that uses
library A's services through TCP sockets, and do not publish
this source. I sell the binaries of B and bundle them with
binaries of socketized version of A. I even put it on
sourceforge - no hidden tricks here.

I can even reasonably argue, that I added valuable new
functionality to the library - now it can work over the
network.

But, this way I circumvented the protection of the GPL which
perhaps author assumed when he choose GPL license. By letter
of GPL, I did nothing wrong, right? But it is a clear violation
of the intent of the GPL, I guess.

Now, a related question. Can the copyright holder of A revoke
the GPL licensing of the existing library? Or is his only option
to either continue new GPLed versions, or scrap it alltogether?
Can I provide the downloadable sources of his previous GPLed
library, regardless of his wishes?

BTW, the original idea is not as evil, as it may sound here -
my original intent was to provide way in which a large number
of low powered, low cost networked devices could use advanced signal 
processing/computational libraries. Then I figured that actually
I could use GPLed libraries this way as well.

Am I correct? Am I evil? (Please answer separately, if possible).

Janez.



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