Johannes Meixner <jsmeix at suse.de> writes: > Hello, > > [snip] > On Jun 6 Olaf Meeuwissen wrote (shortened): >> If GPL'd code uses a non-compatible library via dlopen that's just as >> much a violation as linking to it directly. The code runs in the same >> process space. That makes the combined work a derivative, so, all the >> terms of the GPL need to be met. > ... >> A good rule of thumb is to look at what happens at run-time. If GPL >> incompatible binary stuff and binary bits built from GPL'd source code >> are used by a _single_ process (as jugded by PID), then that's a big >> fat violation. However, if both parts run as separate processes (so >> they have different PIDs) and communicate via a socket or some other >> IPC mechanism, using a trivial or open, well-documented protocol, then >> that is not a violation.
> [snip] > Nevertheless I like to try a proposal how it might be done. > > When the backend uses SANE I/O functionality (sanei), > it must be under GPL. > > Because the license issue is at least not very clear, > the backend cannot link with proprietary stuff. > > But the backend could fork a separated process which runs > whatever proprietary executable and communicate with it > via whatever IPC mechanism e.g. a socket or even via > traditional pipes, see for example the IJS interface > http://hplip.sourceforge.net/tech_docs/hpijs.html HPIJS was designed explicitly to solve the licensing issue. > Therefore only the part which does the basic I/O must be > under GPL but e.g. data compression algorithms could run > as proprietary executable in a separated process. If you don't mind reimplementing the basic I/O yourself, there is no need to put that under the GPL. > A different case are image processing algorithms which > should run in the frontend. Because of the exception in SANE > this can be done in a proprietary frontend executable. But only if the particular backend you use extends that exception. If I were to write a GPL'd backend ... Hope this helps, -- Olaf Meeuwissen FLOSS Engineer -- AVASYS Corporation FSF Associate Member #1962 sign up at http://member.fsf.org/
