Question about commercial use and the GPL

Justin Patterson justinp "at"
Tue Apr 13 14:48:00 2004

I'm interested in using RealVNC as part of a bigger (commercial) support
solution and there are a few modifications that I need to make:
1) I want to be able to have the server shutdown if there's no viewer
connected within a certain timeout period.  This is for a one-time
support-type application, so I don't want to leave the viewer running if
there's a disconnect between the supporter and the supported somehow.
2) I don't want to make any changes to the server's registry or filesystem.
That's because I don't want to interfere with an existing VNC server that
may already be installed (and running) on the machine.  For this, I was
thinking about making it so that it only takes command line arguments to
configure it (and getting rid of the properties dialog).
I've prototyped some of these changes and they seem to work for what I need.
So, my question refers to the part of the GPL which states that a "work
based on the Program" must be licensed under the GPL.  In my case, I don't
mind releasing my modified source for the RealVNC server.  I can contribute
that back to the project if you guys are interested.  Otherwise, I can ship
my modified RealVNC source to my customers.
I am, however, not interested in releasing the source of the web application
(ActiveX controls, Java servlets, etc.) that control the launching of the
server and viewer.  This application does a lot more than just launch VNC
(that's just one aspect of the support relationship), so it's hard for me to
see is as a "work based on the Program."
Can someone please clarify exactly how much of my code has to be licensed
under the GPL to be able to use RealVNC?  Is it just the source code for the
RealVNC binaries?
Thanks for your help,