Re: Simulation frameworks in Java?

[Christoph Schlumpf]

Dear Nelson,

>This is an interesting conversation, but it may be off topic. Do
>people on swarm-support mind it?

Yes, this is an interesting conversation and I do mind it.
>
>Manor says:
>>The next question to worry about is speed. Any thoughts on that issue...
>
>Interpreted Java bytecode is too slow. Compiled Java (via a JIT, or
>just a normal compiler for that matter) could be pretty fast. The
>technology is too new to really say. In theory, Java could compile
>down faster than Objective C, because the extra static type
>information should allow more optimization. In practice I don't know
>that it matters. Java isn't as much a hybrid language as ObjC, which
>could make it slower; I don't understand how much overhead there is
>for, say, Integer.

For Integers, Bytes, Short, Boolean and so on, there exists a Class for
each. If you really do number crunching with these types you can transform
them to simple types (ie int, short, long, ...) these types are no Objects
and there is no overhead left (as far as I understand).

>I imagine this question *must* have been discussed over and over again
>on the net. Anyone know of a good reference?

I don't know a good reference on this topic but you should find information
on the following sites:
http://www.gamelan.com
http://www.javasoft.com
http://www.javaworld.com
http://www.javaology.com

or in any of the comp.lang.java.?????? newsgroups

>As to Thor Sigvaldason's point about
>>       2) Other developpers are investing
>
>I think Java might finally be a real alternative to C++. The choice of
>Objective C for Swarm was always a compromise - we didn't think C++
>was good enough to work with, and we didn't want to write our own
>language. The only thing left was ObjC which, fortunately, was a
>pretty good match.
>
>But that choice was made over two years ago, before Java was on the
>scene. I'm hearing a lot of people say how much they hate C++, and
>isn't Java really nice? If that trend continues then in another year
>or two the status of Java tools will be good enough that one could
>consider doing something the scale of Swarm with it. It's encouraging.
>
>(I increasingly think we made the right call in not writing Swarm in
>C++. More in my next message.)

I strongly support your opinion on C++ and swarm. I think the big advantage
of swarm/ObjC is that it supports dynamical method pointers and class
introspection. If you don't have these futures you still may build a
simulation environment but I think the overhead for programming agent based
simulation without these futures will be big (unless you build your own
language on top of C++).

yours,
Christoph