I just attended an Open Grid Forum event (http://www.ogf.org/OGF22/)
where lat-lon and 52north showed off some very nice WPS work. OGC
plans to work more closely with the Grid community to further improve
our service offerings for distributed computing, but it won't be a
quick and easy process. There's a lot of work to be done in this area.
---
Raj
On Feb 27, 2008, at 9:04 PM, Dr. Markus Lupp wrote:
Hi Randy,
deegree has a WPS implementation (although by now it supports only
WPS v. 0.4.0). We plan to publish an easy-to-install WPS Demo
Release for deegree 2.2, coming in June (1st Release Candidate in
April).
Regards,
Markus
Randy George schrieb:
I noticed OGC finalized the WPS spec:
http://www.opengeospatial.org/pressroom/pressreleases/843
Does anyone know of projects working on WPS implementations?
The goal of WPS is apparently to provide a consistent framework for
interchangeable service process algorithms that can potentially be
chained together into answers to higher level questions than the
typical ‘what’, ‘when’, and ‘where.’ Dealing with ‘why’, ‘how
much’, and ‘what if’ modeling usually requires a process pipeline
for convolutions, boolean band operations, and summary pixel
calculations, all of which are cpu cycle intense, especially for
large imagery sets. In fact cpu usage issues would make the usual
service approach prohibitive. Even the little I have worked on JAI
pipelines shows me the futility of a one cpu to many service
requests approach for WPS.
However, looking at the AWS Simple Queue Service, SQS http://www.amazon.com/Simple-Queue-Service-home-page/b/ref=sc_fe_l_2?ie=UTF8&node=13584001&no=3435361&me=A36L942TSJ2AJA
<http://www.amazon.com/Simple-Queue-Service-home-page/b/ref=sc_fe_l_2?ie=UTF8&node=13584001&no=3435361&me=A36L942TSJ2AJA
>, some interesting possibilities come to mind.
Locking message queues with AMI instance pools is essentially a
poor man’s supercomputer. It would be interesting to look at
harnessing the utility computing concept with instance pools
available for each stage in a process pipeline connected using the
asynchronous SQS service. This is a more or less controlled
‘distributed computing model’ applied to WPS.
Ref here for some examples of existing distributed computing
projects: http://distributedcomputing.info/projects.html
Here are a couple possible approaches to a WPS service model that
might overcome the cpu bottle neck:
1) Sequential SQS pipeline with dedicated instance for each process
node - this would work best for operations amenable to a streaming
pipeline – Boolean band operations or pixel summary operations for
instance
2) Distributed computing model with a chunk server feeding a
pipeline and an array pool of instances processing the chunks
coming down the SQS queue – this would be better suited to tiled
operations
WPS is great when someone else provides the service. I imagine it
would be very interesting to the academic scientific world and
government groups tasked with providing access to all the myriad
imagery coming off space sensor platforms.
Just thinking out loud. More thoughts here: http://www.cadmaps.com/gisblog/?p=28
randy
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--
Dr. Markus Lupp
l a t / l o n GmbH
Kupang-NTT
Indonesia
phone +62 (0)81 339 431666
http://www.lat-lon.de
http://www.deegree.org
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