Hi,
Thank you Ben, you have well summarized what we had the opportunity
to discuss during the recent IGARSS Conference in Denver. Indeed, you
touched three important issues for ES and GIS interoperability.
As you know, we have been working on all the items; thus, we'll be
pleased to experiment the interoperability level of our achievements
in the GALEON phase 2 framework.
---Stefano
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 1.1 spec 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>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>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
