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Dear Stefano and Galeon participants, Thanks for putting together a very valuable document, it must have been a lot of work! Mapping CF-NetCDF to WCS is clearly non-trivial. If I may, I'd like to step back a little and ask a couple of wider (perhaps philosophical) questions. I hope this is an appropriate place to do this - please let me know if not. I have always regarded the OGC standards as a way in which the met-ocean community can communicate its data to other communities. Personally I do not look to OGC standards for providing methods for exchanging data within our community. We already have well-established tools, standards, protocols, data models and software for doing this. When communicating outside ones own community, one often has to accept that a certain amount of information will be lost. I wonder if it is realistic to expect that we might use WCS in future to communicate our data in all its subtlety? My other concern is that the WCS world is changing extremely rapidly, with at least four versions of the specification in existence (1.0, 1.1, 1.2 and "plus"). This contrasts with the relatively small numbers of real WCS servers "out there" in the wild (GALEON has done a great job in encouraging people to stand up real systems but in general, uptake of WCS is rather low). The ISO19123 Coverage model is also likely to be revised as it is broken in places. Can we keep up with this evolution? Thirdly, the WCS1.2 "core plus extensions" model worries me a bit. I understand that the "core" is small, implying that the different community "extensions" will have little interoperability with each other. Effectively, we'll end up with a lot of mutually-incompatible versions of WCS that share some extremely limited features (perhaps only their terminology). The "core plus extensions" model implies that WCS has a desire to encompass all data, a scope that is arguably too wide to be useful or realistic. Personally I would like to see the WCS specification considerably simplified, with a defined list of things that it's good for and things that it isn't good for. For the sake of argument, let's imagine a WCS that only serves data as GeoTIFFs in a lat-lon coordinate reference system (or lat-lon-elevation-time in 4D). Sure, a lot of information would be lost across this interface (e.g. the original data's grid) and certain specialist use cases could not be satisfied (e.g. calculating heat transports). However, it would be much simpler to implement (client and server) and would still satisfy a large number of use cases in which met-ocean data is needed outside our community. I guess I'm saying that I don't think it's realistic or desirable to develop a WCS specification to serve all kinds of geographic data, which is the way things seem to be headed in the OGC world. The effort required to support a small number of specialist use cases (in the specification, in servers and in clients) is fearsome. I think WCS should aim to complement, not replace, technologies such as OPeNDAP by satisfying a different class of user. I think more clarity is needed about the use cases that WCS is thought to satisfy. Best regards, Jon On Wed, Sep 3, 2008 at 11:39 AM, Stefano Nativi <nativi@xxxxxxxxxxx> wrote:
Dear All, Please, find attached the last draft version of the WCS CF-netCDF extension proposal. We apologize for the delay, but the multipart encoding raised several interesting points of deepening. Best Regards, Stefano Nativi Ben Domenico Dominic Lowe Ethan Davis Paolo Mazzetti
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