Hi Mark,
OK, on the Java front, I've looked into several JVMs. I haven't tried to build or test any of them, so I am basing my report on hearsay or claims by the maintainers.
Also my interpretation of documents is likely to be flawed in some respects, so if I have mistaken features of one or other of the JVMs below, please feel free to point it out. I don't pretend to be an expert on any of these packages.
Java does not seem to be required by any of the OOo components. However, plugins used by OOo components or installed by the user or an application using OOo as a run-time system, can use Java (eg Basic for OOo). So the installation will be limited in usefulness without Java.
I have not looked into the APIs used by OOo components or plugins, but I am sure they could be adapted to any of the JVMs listed below.
All the JVMs seem to use Classpath these days, I guess it has evolved to a mature state at last. All are GPL.
Kaffe: Uses Jikes for compiling, but other compilers can be used. Kaffe is a living organism, the last release was in March this year. Kaffe does not have a working version of its JIT for the PPC, but the interpreter is OK. Kaffe uses AWT for graphics, I seem to remember that getting AWT to work on OS4 is a big job. Cacao: Latest version released in February this year. AFAICS Cacao does not have an interpreter, only a JIT. Cacao has the advantage that it has already been ported to OS4 by one of the OS4 developers. Graphics package is GTK, that has not yet been fully ported. Janos: has an interpreter and JIT, but JIT for PPC is incomplete. Has much in common with Kaffe (run by Timothy Stack, one of the Kaffe leaders). Seems to be on the shelf, no new updates released since February 2003. gcj: This is a front end for gcc. The back end can be PPC or any other platform. gcj is a compiler only, but can be linked with gcjlib, a run-time library. I don't know what is available in the way of interpreter/JIT. jikes: This is an IBM invention, binary only, I believe it can be included in commercial packages, but I could be wrong. The licence needs looking into. Jikes is a compiler only, and produces bytecode that can be interpreted or JITted. JAmiga: This is a new-ish implementation that started out as a hobby project (I believe Peter, one of the devs, is on this list). I have not been able to find an up-to-date status for JAmiga (eg AWT graphics, Classpath usage, etc). Perhaps Peter can give us an update on JAmiga.
There are others, but I have listed the main contenders. For our purposes we could make do with any of them, but each one requires a different amount of work to adapt it to our environment. Possibly Cacao has the greatest promise, since it has recent releases and one of the OS4 developers claims to have ported it already. He has said that he is working on the GTK part at the moment. He made that announcement back in April, and I exchanged a couple of emails with him, but recently he has gone quiet and must be busy. A GTK port has even made it to aw.net with a MUI engine: http://amigaworld.net/modules/newbb/viewtopic.php?topic_id=18978&forum=3...
I have sent a couple of emails asking the OS4 dev if he would allow his name to be quoted, but without result, so I can't name him just yet. I also asked if he would share his work with us or even join the team, again, no reply.
cheers