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Hi Ben:If the netcdf encoding is just an extension (rather than at the core of WCS), and if it is not supported by the larger WCS or OGC community (ie. if most WCS clients or servers do not support it), then it is not serving the purpose of providing interoperability between communities, which would seem to be the purpose of this effort.
The GALEON effort has been very strong, and a lot of great work has been done. But is this viewpoint supported by the larger WCS or OGC community? Recent decisions about WCS would seem to suggest not. I would return to my email of last week. Where in OGC land is there something that is close in viewpoint to that of the metocean community? IMO it is CSML - the mapping between CSML Feature Types and Datatypes in the proposed CDM is very close. Rather than try to force a harmonization on the WCS level, where the larger WCS community does not appear to be interested, why not work for closer harmonization with CSML, with gateways and translators, and since the CSML folk are heavily involved in OGC, use whatever OGC transport layers/ service requests they develop for CSML as the ones that will provide the bridge.
Sort of half-formed ideas (Steve is always much more articulate than I), but I think you get the idea.
-roy On Sep 23, 2008, at 3:19 PM, Ben Domenico wrote:
Hi Steve,First, thanks to you and Jon for your thoughtful emails. It will take me a while to digest them more fully and come up with a follow up to the discussion -- especially the OPeNDAP suggestions.But there is one point that's a bit puzzling to me. I agree with the view of "WCS as an OGC-accepted vehicle for interoperability *between* our community and others." But I don't see how it follows that "It is not clear that embedding netCDF into WCS any longer holds promise of contributing to that goal." To the contrary, my own sense is that great progress has been made toward that objective and Stefano's draft encoding specification gets us over the last remaining major hurdle.What have I missed here? -- BenOn Tue, Sep 23, 2008 at 12:02 PM, Steve Hankin <Steven.C.Hankin@xxxxxxxx > wrote:All,Jon has done an excellent job of expressing the fundamental concerns that I also see. I ask your indulgence at for tossing yet-more radical ideas into the ring.It remains imperative that our "fluid earth science" community continue to explore all useful angles of connection with the OGC community. The contributions that GALEON has already made in this regard are enormous, and from all that I have observed are very broadly recognized and appreciated. For myself, I cannot thank you enough. Finding this much time and energy to devote to community standards while also meeting "day job" demands is extraordinary.I would like to pose this question: is GALEON at a point where it should take stock, re-evaluate goals, and possibly make a significant course change? That is a very hard thing for an individual to do, and a much harder thing for an organization to do. With the WCS 1.2 "core plus extensions" approach, we have effectively seen the broader OGC community reject involvement in the level of complexity that our community requires in order to conduct its internal business. As Jon says, arguably the central goal of GALEON was to explore WCS as an OGC-accepted vehicle for interoperability *between* our community and others. It is not clear that embedding netCDF into WCS any longer holds promise of contributing to that goal.If this interpretation of recent decisions is correct, then how should we adapt? What approaches will best meet our community's needs? With the combination of netCDF, CF, and OPeNDAP we have a powerful and effective vehicle for interoperability that has already gained quite broad acceptance within much of our community. The use of OGC-accepted solutions is, however, mandated for many of our partners, and that has created a schism. A true fusion of OPeNDAP and OGC could mend that schism and lead to a huge interoperability success story for our community. How can we best blend the virtues of netCDF/CF/OPeNDAP with the OGC process? Is there work that GALEON could pursue to "bless" OPeNDAP transport under an OGC/WCS banner? Can we envision, for example, a community extension to WCS that returns an unconstrained OPeNDAP URL as the payload of a WCS data request? This would essentially provide an OGC-accepted segue from WCS into OPeNDAP. With relatively minor effort at relinking, any application that can read netCDF can read OPeNDAP, so this is not far from what GALEON is currently exploring using netCDF-CF files as a WCS payload.And how to approach interoperability with users outside of our own community? Jon's suggestion of "the WCS specification considerably simplified" seems very sensible. And this approach would dovetail well with the recent work on server-side regridding through OPeNDAP. It is easy to envision OPeNDAP servers as gateways -- providing simple lat-long versions of our gridded data that are then formatted as geoTIFF files and delivered through the simplest WCS syntax.2 cents (or maybe 4) - Steve
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