On Jan 10, 2013, at 10:33 AM, Yoshiki SATO <[email protected]> wrote:
>> Yes -- IIRC, the Java interface isn't really dependent upon anything
>> specific in the back-end C implementation of Open MPI. So I'm
>> guessing/assuming that if you can build it, it should work against the 1.6
>> OMPI C engine just fine.
>
> Sounds good :-) I'm going to try to build it anyway, and let you know if
> stucked.
Cool.
>> Is MPI-for-Java of interest to you? I ask because Ralph and I have been
>> trying to figure out how to get the cycles to do more with the Java
>> interface (e.g., make it more like a 1:1 set of bindings). Is this
>> something you'd be willing to work on / contribute, perchance?
>
> Yes. This is because one of our roles is enabling Java applications to run
> on top of the K computer (Fujitsu), which prevents user processes from TCP/IP
> communications directly. It only allows communications via customized
> openmpi (scheduler) between inter node communications.
Gotcha.
> BTW, I don't fully understand what a 1:1 set of bindings mean. I believe
> that the interfaces defined in mpiJava was carefully designed to match the
> MPI spec, and then should be a 1:1 set of bindings. Otherwise, I'm willing
> to contribute something to make it better ;-)
I think they're *somewhat* close; I don't think that they're exactly a
one-to-one mapping to the C bindings. I know that they added the "offset"
argument for choice buffers, and I can see what that would be necessary. So
that should probably stay.
But extras like MPI.OBJECT should probably disappear, and be replaced with
proper support for Java-isms (e.g., N-dimensional arrays -- see posts from
Siegmar on the users list about how N-dimensional arrays don't work because
OMPI is assuming that they'll be contiguous in memory, but Java allocates, for
example, a 2D array as a series of 1D arrays). And any other interfaces that
aren't nearly identical to what the MPI C++ bindings are (were) should probably
also go, unless there are strong reasons to *need* them.
I've setup a Bitbucket for this Java work, if you would like to contribute.
It's a branch from the Open MPI SVN trunk; I can keep it up to date. If you
send me your Bitbucket ID, I can give you write permissions.
https://bitbucket.org/jsquyres/ompi-java-revamped
--
Jeff Squyres
[email protected]
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