Ben Domenico
August 14, 2006
The main accomplishments of GALEON Phase 1 are several modifications to the WCS specification incorporated into the WCS 1.1 version. One of the key modifications is that a netCDF-CF application profile has been drafted and will be among the first binary encoding profiles associated with the WCS 1.1 specification which replaces the list of 5 acceptable binary encoding formats in favor of a requirement that encoding formats be documented in an applications profile:
http://www.unidata.ucar.edu/projects/THREDDS/GALEON/WCS-Encoding-Profile-For-CF-netCDF.doc
Detailed status information on GALEON is being shifted from the wiki
to the OGC GALEON network pages at:
A related set of demonstrations chaining together services is being hosted by the ESIP Federation. Many of these demos involve GALEON technology and collaborators
Recent presentations and follow up discussions at the OGC Technical Committee meetings, the Unidata User Workshop, the ESIP Federation meeting, IGARSS 2006, and the ESRI Annual User Conference have resulted in a set of objectives for Phase 2 of the GALEON Interoperability Experiment. The primary goals can be divided into 3 categories:
mplement 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:
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
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.
Note that the 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 two of the major phase 2 objectives.
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:
Some effort toward testing the applicability and effectiveness of these approaches would be valuable.
This is a pretty full agenda, but not all the participants will work on all the items. On the other hand, it will 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