Hi everyone,
I'd like to respond to the wet blankets below, but will lead with the
caveat that I'm not a user or developer of WCS, OPeNDAP, or CF/netCDF,
so I may be missing some crucial nuance or historical background. I'm
coming at this from my GIS data modeling background, and my
perspective on standards. (I actually like wet blankets, especially in
the Texas summer heat we've been having ;-) This is an interesting
discussion, including Bryan's blog thread linked below, "WCS is dead,
long live WFS". I'm curious what presentation gave you a horrific
picture of the future of WCS, and what was horrific about it. Btw, WFS
has the same deficiency as WCS when it comes to predicting how big the
response will be; that's a function-point I'd sure like to see in
those web services.
Back to CF/netCDF... When I was in a recent DMAC meeting with Ben D,
Steve H, and Jeff DLB (among others), the concept of making CF/netCDF
an OGC encoding standard or Best Practice came up as a potentially
good idea from the standpoint of broader industry recognition, and to
provide additional convening resources for long-term maintenance if
that were of interest (at least for CF, probably not needed for netCDF
or OPeNDAP). That didn't seem to imply to me the need for additional
work in reconciling CF/netCDF with the ISO/OGC model-driven approach
as Andrew described below. I agree the ISO/OGC model-driven approach
has merit and broad applicability, but the KML exception is a case in
point that not all standards must fit in the same conceptual
framework. KML was in fact the precedent in my mind for bringing CF/
netCDF into OGC. It simply gives a bigger tent for the communities
having awareness and access to that standard. Whether it needs to
migrate in some way to fit the ISO/OGC abstract model is up to the
marketplace, which consists of you folks and your user base. "If it's
not broke, don't fix it."
I think it's a strength of OGC's process that we don't have to fit
everything into a single framework. While it might seem simpler and
more practical, and maybe even intellectually stronger, to want all
geospatial standards to fit in a common framework, that would
inevitably be a limiting constraint, fighting natural evolution. We
need to be open to other ideas and frameworks of practice. And
standards processes take a long time to result in mature, effective
standards. OPeNDAP and CF/netCDF already qualify as mature, effective
standards, so I wouldn't recommend changing them just to bring them
into OGC. (Okay, so irregular grids aren't yet supported, so get on
with it. :-) But I firmly believe co-branding will help both our
communities by strengthening our communication and technology base.
As OGC is having increased interaction with the hydrology, meteorology
and ocean observing communities, this seems like a natural standard to
acknowledge and support within OGC.
As to this being "just publicity" as Bryan suggests, that seems to me
to disregard the value of open community participation and cross-
fertilization of ideas that take place within the OGC community and
processes. Perhaps you're concerned about the potential for reduced
control over the interface definition, but that's not what will happen
-- you won't lose control over it. There may be variations and
profiles for special applications that emerge, but that wouldn't
require you to change what already works. I think you'd find the
positive effects of synergy with other technologies and approaches
would repay the collaboration effort many-fold. This could also bring
your issues and concerns with WCS more directly to that working group,
if they're not already being considered.
I apologize immediately if I've missed or misrepresented any of the
issues with CF/netCDF or OPeNDAP. Please take this at face value. At
the end of the day, I just want to see stronger relationships and
stronger technology. And I think the relationships, personal and
institutional, matter more than the technology, because having better
relationships will lead to better solutions, whatever technology is
chosen.
Cheers,
dka
--
David K Arctur
Open Geospatial Consortium (OGC)
darctur@xxxxxxxxxxxxxxxxxx http://www.opengeospatial.org
"The mark of a moderate man is freedom from his own ideas. For such a
person, nothing is impossible."
- Tao Te Ching
On Jul 17, 2009, at 12:46 AM, Bryan Lawrence wrote:
Hi Folks
I really think it's important to distinguish between CF and netCDF in
this discussion ...
Two elements follow, negative, then positive:
<moreWetBlankets value="netcdf">
Without any collusion with Andrew, I was already thinking along the
same lines.
I was initially fairly enthusiastic about this idea, in private email
I stated the following (in regard to an early version of this idea):
Anyway, a quick take on this is that our CF white paper talked about
separating the information >content from the netcdf serialisation.
OGC might provide a suitable venue for the former, I doubt >that
it's appropriate for the latter.
The point of the last sentence is that, unlike Microsoft, if we go
into an external standardisation process, we should expect that
process to make changes. Do we really want that for netcdf, given the
number of existing implementations?
If we don't, then if OGC rubber stamps existing practice, then what
have we achieved (with all the effort)? Well, we have achieved
- a defined encoding (oops, we have one of those).
- a badge (well that's useful sometimes, especially for dealing with
governments, but NASA carries some cachet, even over here),
- publicity into new communities (ah well, that is important ...
getting more people using netcdf has to be a good thing, and
realistically OGC talks to the parts of the body that NASA can't/
doesn't reach - with apologies to a well known beer advert).
So is this really just about publicity? Are there other ways of
achieving that which would require less community effort? (Sometimes I
think standardisation efforts are for their own sakes. Yes I'm a big
supporter of standardisation processes, but not for everything, and
any given entity doens't have to carry everyone's standardisation
badge).
</morewetBlankets>
<cuddlyThoughts value="CF">
I still think the semantic encoding concepts could well be split out,
and they do fit nicely alongside other OGC type activities.
What we might get is a process for advancing CF and more recognition
that the work done on *advancing* CF is worthy of our time. I think
we all agree that the process of moving CF along is bogged down by
lack of attention from those of us who are invested in doing so, but
have day jobs doing other things. Using OGC gives this work more
"fundability" (e.g. it counts as "Knowledge Transfer" for academics in
this country).
That said, what I've seen of the current state of WCS doesn't exactly
inspire me that OGC would necessarily make things any better
( http://home.badc.rl.ac.uk/lawrence/blog/2009/04/23/wcs_is_dead%2C_long_live_wfs
)
</cuddlyThoughts>
Cheers
Bryan
On Thursday 16 July 2009 21:29:00 Woolf, A (Andrew) wrote:
<wetBlanketMode>
I’m having some trouble digesting exactly the proposal here. From
where I sit, we already have a perfectly well-defined and
standardised encoding format (netCDF) – if we want a document, we
can point to the NASA spec. We also have a set of conventions for
that format (CF) that are well-governed within an existing community
process. I’m having trouble seeing what OGC brings to this. The
added value, it seems to me, would come from integrating netCDF/CF
within the framework ISO/OGC abstract approach to data
interoperability, which is being adopted very widely across many
domains (ref. the multi-billion € INSPIRE infrastructure). That
approach is very simple and very clear – you first define a
conceptual model for your universe of discourse (in which exchange
and persistence formats are explicitly out of scope), then you
(auto)generate a canonical encoding for that model, thereby enabling
interoperable data exchange. CSML was one attempt (ours) at the
conceptual model bit, and we’ve shown that, *at least for current
usages* of CF-netCDF, the ISO/OGC standard encoding of that model
(i.e. GML) works perfectly well with netCDF *as-is*! (Incidentally,
the CSML feature types and CF Point Observations proposal are in
almost perfect alignment, meaning that the ISO/OGC standard approach
works with even more confidence for current and proposed CF/netCDF.)
I’m not sure what extra standardisation is being proposed. On the
other hand, I am very nervous that by merely ‘rubber-stamping’ CF/
netCDF with an OGC logo, without first getting right the underlying
foundations (i.e. an agreed standards-based conceptual model), we’ll
be headed to even more confusion ultimately (this is the reason
there is so much hand-wringing about how exactly to bring KML into
alignment with the rest of the OGC standards family – it doesn’t
share a common base). I’d be very interested to hear David Arctur’s
view on how exactly it was proposed actually to *integrate* CF/
netCDF into the OGC frame, as opposed to just attach an
OGC label, and to point out why such integration requires new CF/
netCDF standardisation activity. In my view, such integration is
already possible and happening.
</wetBlanketMode>
Regards,
Andrew
From: galeon-bounces@xxxxxxxxxxxxxxxx [mailto:galeon-bounces@xxxxxxxxxxxxxxxx
] On Behalf Of Ben Domenico
Sent: 15 July 2009 19:29
To: Unidata GALEON; Unidata Techies
Cc: Mohan Ramamurthy; Meg McClellan
Subject: [galeon] plan for establishing CF-netCDF as an OGC standard
Hello,
At the galeon team wiki site:
http://sites.google.com/site/galeonteam/Home/plan-for-cf-netcdf-encoding-standard
I put together a rough draft outline of a plan for establishing CF-
netCDF as an OGC binary encoding standard. Please note that this is
a strawman. Comments, suggestions, complaints, etc. are very
welcome and very much encouraged. It would be good to have the plan
and a draft candidate standard for the core in pretty solid shape by
early September -- 3 weeks before the next OGC TC meeting which
starts on September 28.
One issue that requires airing early on is the copyright for any
resulting OGC specification documents. Carl Reed, the OGC TC chair
indicates that the wording normally used in such documents is:
Copyright © 2009, <name(s) of organizations here>
The companies listed above have granted the Open Geospatial
Consortium, Inc. (OGC) a nonexclusive, royalty-free, paid up,
worldwide license to copy and distribute this document and to modify
this document and distribute copies of the modified version.
I'm sending a copy of this to our UCAR legal counsel to make sure we
are not turning over ownership and control of the CF-netCDF itself..
-- Ben
--
Bryan Lawrence
Director of Environmental Archival and Associated Research
(NCAS/British Atmospheric Data Centre and NCEO/NERC NEODC)
STFC, Rutherford Appleton Laboratory
Phone +44 1235 445012; Fax ... 5848;
Web: home.badc.rl.ac.uk/lawrence
