[galeon] Clarification re: core/extensions approach to OGC WCS

• To: "Unidata GALEON" <galeon@xxxxxxxxxxxxxxxx>
• Subject: [galeon] Clarification re: core/extensions approach to OGC WCS
• From: "Ben Domenico" <Ben@xxxxxxxxxxxxxxxx>
• Date: Tue, 13 May 2008 10:51:46 -0600

Hi all,

Judging from a few reactions to my earlier note summarizing the highlights of the WCSplus 
meeting at the EGU last month, I may have given an unintended negative impression 
regarding the fact that the OGC WCS standards working group is moving in the direction of 
a standard that consists of a rather limited core and a set of "extensions."

In fact,  I believe the division of WCS into a simple core with extensions is a 
good thing.   Until now,  WCS was following a difficult path in trying to 
specify one comprehensive interface that satisfies the needs of all possible 
WCS user communities.  As we were learning in WCS 1.1, standards that attempt 
to satisfy all possible use cases just become too bulky and unmanageable in 
practice.   Having watched this occur in many of it's standards efforts, many 
of the OGC standards are moving in the direction of core plus extensions.

In terms of the role of GALEON in this WCS evolution, our immediate goal is to 
have a CF-netCDF binary encoding document for WCS in time for the OGC technical 
committee meeting in June.  In my view, that will be the linchpin for a WCS 
that satisfies the requirements of our community.  But it's likely that we'll 
have additional work to do for some of items I listed in the earlier note:

-- 3 spatial dimensions (I believe this may still be under discussion for the 
core)
-- multiple time dimensions (e.g,, forecast run time and forecast time)
-- time relative to the present (e,g., the most recent radar image)
-- non-spatial coordinates (e.g., atmospheric pressure as a proxy for height)
-- non-gridded coverages (e.g., John Caron's proposed CF convention for point 
data collections)
-- asynchronous response

With the new approach of core/extensions, however, we should only have to come 
up with specs that satisfy the community who will use those features in their 
clients or servers rather than attempting to get universal agreement that every 
WCS client and server has to provide all these functionalities.

I hope this clarifies my personal assessment of the direction the OGC standards 
working group is taking with regard to WCS.

-- Ben