Hi,
During the last several weeks at the Unidata User Workshop, the ESIP Federabion
meeting, and at IGARSS 2006, I had the opportunity to discuss possible
objectives for the GALEON Phase 2 Interoperability Experiment with a number of
GALEON paricipants. From what I can decipher from my cryptic notes, the goals
can be divided into 3 categories:
1. Implement and test clients and servers that conform to the new WCS 1. 1spec
and experiment with them on a wide range of real-world datasets. From the
GALEON perspective, some of the important changes in WCS 1.1 are:
-- multiple coverages in one request
-- multiple fields in a coverage
-- 3 spatial dimensions
-- 2 time dimensions (e.g., the time a forecast was run and the forecast times
within the run)
-- relative time (e.g., the latest image, the last 5 images, ...)
-- non-spatial dimension (e.g., pressure or density)
-- irregular grids
2. Catalogs and/or WCS getCapabilities lists? The getCapabilities request
appears to be inadequate to return a list of all the coverages on a WCS server.
Several people have suggested that GALEON Phase 2 include experiments that
involve CS-W (Catalog Services for the Web) as well as WCS. As an
illustration of the challenge, the top level THREDDS catalog represented in
HTML at:
http://motherlode.ucar.edu:8080/thredds/catalog.html
includes several catalogs of catalogs of different types of real time datasets. If you
drill down in the "NCEP Model Data," you'll get to collections of many
datasets, each of which contains hundreds of coverages. These catalogs are being updated
in near real time as new data arrive. Currently these datasets are catalogued using
THREDDS technology, but it would be good to have a standards-based interface as well.
Without such catalogs, the WCS interface is much less effective.
I should add that those NCEP model output datasets also exhibit all the
characteristics suggested for interoperability testing in item 1 above so they
can be used as grist for a couple major phase 2 objectives.
3. GML dialects
There appears to be an accelerating trend to develop new XML schemas for many
subdisciplines in the geosciences. Even within the world of GML, many profiles
are evolving. Within the GALEON team discussions, at least 3 have come up in
the context of methods for characterizing CF-netCDF characteristics in a
standard form:
-- ncML-GML
-- CSML
-- GMLJP2
Some effort toward testing the applicability and effectiveness of these
approaches would be valuable.
This is a pretty full agenda, but I would not expect all the participants to
work on all the items. On the other hand, it would be usefull to have at least
some effort focuse in each area.
There have also been some suggestions relating to web processing and chaining
services, but the general sense seems to be to leave that to the OGCnetworks --
GALEON and GSN and to collaborate with the ESIP Federation endeavors in that
realm. See:
http://wiki.esipfed.org/index.php/Web_Services
I am going to send a copy of this to a few colleagues who expressed an interest
in the work but are not part of the GALEON team ... yet.
Please let us all know which (if any) aspects of the imposing list of
objectives your group would likely participate in. Comments or corrections to
any of this are welcome.
-- Ben
