m.b.taylor at bristol.ac.uk
Thu Mar 12 04:18:44 PDT 2009
On Wed, 11 Mar 2009, Allan Brighton wrote:
> Mark Taylor wrote:
> >> I was also wondering if SAMP would be suitable for a quick-look application?
> >> (I guess it would depend on how quick...)
> > Can you expand on this - I'm not sure what you've got in mind.
> > Mark
> I was thinking of a situation where you could, for example, keep updating a
> FITS file with images from the telescope and send a "image.load.fits" SAMP
> message each time a new image is ready. It would be easy to implement, but
> a custom solution might be required (or just a custom SAMP message, if the
> performance is good enough). We did this sort of thing in the past with
> Skycat and mmap'ed FITS files or image data in shared memory.
Yes there's no reason you couldn't use SAMP for the messaging component
of this. For an mmap'ed FITS file the normal image.load.fits message
might work, depending on exactly how it was interpreted at the receiving
end. If one of the existing MTypes wasn't suitable you could just come
up with a new one, e.g. image.load.shmem with a shared memory key
as a parameter or something similar. Depending on how specific this
MType definition was to your requirements, it might or might not
get taken up by other applications doing different things to what
you were doing.
Performance: I see something in the region of 5-15 ms per message
using a JSAMP hub and client running on the same machine, depending
on various options like message delivery pattern and hub logging mode
(I used the JSAMP calcstorm tool for benchmarking). Probably quick
enough for a quick look?
Mark Taylor Astronomical Programmer Physics, Bristol University, UK
m.b.taylor at bris.ac.uk +44-117-928-8776 http://www.star.bris.ac.uk/~mbt/
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