I have converted this to a unidata bug report.
See https://www.unidata.ucar.edu/jira/browse/CDM-68
=Dennis Heimbigner
John Caron wrote:
Hi Roy, Roberto:
Yes, we see the problem and will get a fix for it, thanks!
John
On 11/27/2011 8:13 PM, Roy Mendelssohn wrote:
Hi All:
This came up in the pydap mail list. I am quoting Roberto here:
Sorry, but the fact that it works with some clients doesn't mean it's
working as intended. In that dataset there are two different ways to
retrieve the time axis:
(1)
http://thredds1.pfeg.noaa.gov/thredds/dodsC/satellite/GR/ssta/1day.dds?analysed_sst.time
(2)
http://thredds1.pfeg.noaa.gov/thredds/dodsC/satellite/GR/ssta/1day.dds?time
If you check the DDS responses above, you'll see that the two are
identical. This is because "time" is a map in the "analysed_sst"
grid, but also a variable in the root dataset, as we can see from the
unconstrained DDS:
http://thredds1.pfeg.noaa.gov/thredds/dodsC/satellite/GR/ssta/1day.dds
Now, if you replace the ".dds" extension in the two requests above
with ".dods", you'll notice that the first one returns a "Request Too
Big" error, while the second one is fine. My guess is that there's a
bug in the code that estimates the size of the requests.
Why does this work with other clients? As far as I know, pydap is the
only opendap client that does requests for the grid map (request #1
above), instead of requests for the root variable (#2). Other clients
that I've seen prefer the second approach. I use the first one
because... well, guess because I'm a purist who sometimes favors
purism over practicality*. :-P
I can confirm what he reports here (it actually started with an email
from Chris Mueller who was getting the reported "Request too big"
error on some datasets even though he was making small requests using
the pydap client code. If you use the html page or ERDDAP or toolsUI
it works, but it fails with pydap for the reason given. I believe
Roberto is correct here that you should be able to query the grid map,
which means there is an error of some sort.
-Roy
**********************
"The contents of this message do not reflect any position of the U.S.
Government or NOAA."
**********************
Roy Mendelssohn
Supervisory Operations Research Analyst
NOAA/NMFS
Environmental Research Division
Southwest Fisheries Science Center
1352 Lighthouse Avenue
Pacific Grove, CA 93950-2097
e-mail: Roy.Mendelssohn@xxxxxxxx (Note new e-mail address)
voice: (831)-648-9029
fax: (831)-648-8440
www: http://www.pfeg.noaa.gov/
"Old age and treachery will overcome youth and skill."
"From those who have been given much, much will be expected"
"the arc of the moral universe is long, but it bends toward justice"
-MLK Jr.
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