I haven't heard about DRMAA before, but it looks like it would make a
_very_ nice compliment to the Objective-C API for Xgrid. Their Java
bindings in particular look like they mirror the APIs that Brian
Granger and I have created in making procedural Python APIs for Xgrid
(well actually, it's probably the other way around). As you may know,
both Brian's pyxg and my xgf modules suffer from the problem that they
implement this API on top of a somewhat fragile foundation (Brian,
forgive me if I'm stepping on your toes here). PyXG wraps the xgrid
command line tool and my xgf wraps the XgridFoundation framework using
twisted but runs into problems because it has to manage its own
NSRunLoop, making it hard to integrate into an app that already has a
run loop. I can't speak for Brian, but I would be happy to replace my
code with Python bindings to a DRMAA library for Xgrid (in fact, the C
library would obviate the need for a Python library at all in order to
use Xgrid from within Matlab).
I am not familiar with the DRMAA library so I can't really comment on
it specifically.
I fully agree with Barry that the two current APIs for Xgrid (the
command line and XgridGoundation) make it very difficult to do
certain things. While wrapping the command line works, it is not a
robust solution for the long term for a python (or another language)
binding for Xgrid (like pyxg). In terms of XgridFoundation, it is
fine for working in a Cocoa App, but again, it is very fragile in a
setting where you have to manage your own NSRunLoop. I would _very_
much like to have a different API for Xgrid. Some of the needs that
I see:
- An APi that is easy to call from a variety of languages. This
means it would probably be in C.
- An API that is not based on an event loop. This probably means
using callbacks. But it would also be nice to have a fully
synchronous API. The reason that this would be very useful is that
most scientists develop/execute code in a synchronous manner using a
compiled language C/C++/fortran or a scripting language like perl/
python/ruby/etc.
Having an APi with these characteristics would make it much easier to
write a robust Python API for Xgrid. And I would love to be able to
rewrite pyxg to use such an API.
I'm not sure that the DRMAA and Objective-C API are so incompatible.
We've had some discussion on the list already about a more procedural
API for Xgrid. It would seem that the DRMAA implementation could be
made on top of (and maybe even compatible with) XgridFoundation--a
more robust version of what I've done in xgf. A higher-level, more
procedural API would allow non-Cocoa developers easy access to Xgrid
and would allow Cocoa developers to make quick, prototype code by
firing off a thread that submitted a job and waited on the results
using the procedural API. More interactive use could be added when/if
needed using the XgridFoundation API.
I mostly agree with this. My only comment is that I would prefer to
have a procedural APi that mimics the existing XgridFoundation one as
closely as possible. Then if someone wants, the DRMAA interface
could be built on top of that. Maybe that is too many Xgrid API's
though?
Finally, layering DRMAA on top of Xgrid Foundation would mean that
apps written to the DRMAA API might be more easily ported to other
grid engines if needs changed.
A good point.
Thanks for bringing this project to the lists' attention. It's an
exciting development for those of us who didn't know about it already!
Barry
On 2/27/06, Ernest Prabhakar <email@hidden> wrote:
Hi all,
Is anyone here familiar with the Distributed Resource Management
Application API (DRMAA):
While their procedural bindings not a great match for our Objective-C
API, it occurred to me it might be of interest to some of you work on
Python et al. Have any of you run into DRMAA-enabled applications in
your environment?
If this is something you're interested in exploring, please reply to
the list, and CC Andreas Haas (above) from the DRMAA working group.
Best,
-- Ernie P.
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Ernest N. Prabhakar, Ph.D. (408) 974-3075 <ernest at apple.com>
Xgrid Product Manager, Mac OS X Product Marketing
Apple Computer; 303-4SW 3 Infinite Loop; Cupertino, CA 95014
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