Geir Magnusson Jr wrote:
I applaud Archie for his candor and openness wrt these issues so far, and suggest that Archie is in the best position to lead off the discussion :) [hint]
Umm, ok here goes :-) There are a couple of different issues. I'll try to separate them out to the best ability of my own understanding. A little background: copyright covers the "expression" of an idea. To cover the idea itself, a patent is required. This issue is about copyright; nobody is claiming that SableVM has exclusive rights to any algorithms AFAIK. 1. As for "credit", clearly JCVM uses and reimplements many ideas and algorithms from SableVM. This should be obvious. I have a lot of respect for Etienne's work. The SableVM project as a whole deserves all of our respect. Quoting the JCVM manual: http://jcvm.sourceforge.net/share/jc/doc/jc.html An acknowledgment is due here. JC borrows heavily from Etienne Gagnon's innovative SableVM Java virtual machine implementation. Several ideas have been blatantly stolen from SableVM, including bidirectional object layout, the object lockword design and spin-free thin lock algorithm, per-class loader memory allocation, and thread management. In fact, without SableVM as an example to work from this project would probably have never been attempted. Of course, any errors in translation are mine. Whether credit is due is not in question. 2. The copyright issue is the main one in question. JCVM was LGPL, so there was never an issue. When I donated JCVM as JCHEVM, copyright became an issue because of the new license. My thoughts at the time are here: http://issues.apache.org/jira/browse/HARMONY-3 In JCHEVM, the thread handling and thin lock algorithms are very much the same algorithms, and my implementation contains similiar function names to SableVMs, etc. The code is written differently but basically does the same thing. After all, an algorithm is a bunch of exact steps that must be executed in a certain order. So does JCVM constitute a "different expression" under the copyright law? That's the question -- and not one for me, for IANAL and TINLA. The truth is apparently no one really knows for sure. How "different" does some software have to be before the copyright no long applies? (Rhetorical question) There is a spectrum between cut and paste (clear violation) and completely different implementation of the same idea or algorithm (clearly allowed as long as there is no patent). In between people can have different opinions of where the line is drawn of course. 3. So what do we do? My wish is to give SableVM the benefit of the doubt. If there's something in there they claim is "theirs", we can take it out and replace it. I'd rather do that than argue about it. We should remember that JCVM owes SableVM a debt of gratitude and respect their wishes. In particular there are lots of thread handling and locking algorithms, and these AFAICT are the only two areas of the code that might be considered "not different enough" (though I haven't heard back from them yet exactly what they are claiming), and these are easily replaced. There's also the possibility that SableVM folks could give their blessing and donate their code, but that might have practical difficulties because all the SableVM contributors would have to agree to the new license (though I'm one of them, so my vote would be easy :-) -Archie __________________________________________________________________________ Archie Cobbs * CTO, Awarix * http://www.awarix.com
