Re: [ferret_users] Ferret to access ipcc opendap server

Hi David,
Using the example on this page,

http://www2-pcmdi.llnl.gov/software-portal/esg_data_portal/dapserver#CDMS_access

I was able to open a dataset in Ferret by specifying the username and password:

yes? use "http://username:passwd@xxxxxxxxxxxxxxx/dap/ipcc4/20c3m/ncar_ccsm3_0/pcmdi.ipcc4.ncar_ccsm3_0.20c3m.run6.atm.mo.xml"

However, that seems to be a dataset that doesn't actually require security. It works without the username and password as well. I tried the URL you gave, and with the newer version of Ferret -I tried it with v6.08 and v6.1- both of which translate OPeNDAP error messages,

**Internet Data error
OPeNDAP Error: Error while reading the URL: http://username:passwd@xxxxxxxxxxxxxxx/cgi-bin/dap-cgi.py/ipcc4/20c3m/mri_cgcm2_3_2a/pcmdi.ipcc4.mri_cgcm2_3_2a.20c3m.run1.ocn.mo.xml.dds?.
The OPeNDAP server returned the following message:
Unauthorized: Contact the server administrator. (OPeNDAP/netCDF Error code 1001)

We'll look into this some more; Ferret just passes the entire URL into the OPeNDAP library call to open the file, so I'd have thought this would work.

Ansley

David Wang wrote:

Hi Peter,

Thanks for your response. Yes, I do have a username/passwd. So I can access the metadata via dncdump and I can also access the data in Matlab through opendap-enabled mexnc. But in FERRET I had no luck. However I am able to access an restricted dataset at IRI/LDEO w/ username/passwd (in FERRET). So something is peculiar with the ipcc server, I guess.

D.

On Tue, Apr 15, 2008 at 10:11 PM, Peter Cornillon <pcornillon@xxxxxxxxxxx> wrote:

Hi David,

I tried to access the server, but found that it is password protected. It seems however that you must have accessed it to get the metadata. Do you have a username/password? Does ferret allow you to access password accounts?

Peter

On Apr 15, 2008, at 8:49 PM, David Wang wrote:

Hi Ferreters,

I wonder if anyone has ever successfully accessed the opendap server for IPCC AR4 model output (http://esgcet.llnl.gov/dap/ipcc4) in FERRET. I tried, for instance in FERRET V6.1:

yes? use "http://username:passwd@xxxxxxxxxxxxxxx/cgi-bin/dap-cgi.py/ipcc4/20c3m/mri_cgcm2_3_2a/pcmdi.ipcc4.mri_cgcm2_3_2a.20c3m.run1.ocn.mo.xml"

but failed:

**Internet Data error
               (OPeNDAP/netCDF Error code 1001)

While dncdump -h can correctly display the meta data of the above opendap URL. I wonder if this is because FERRET cannot deal with authorized opendap access. Those U.S. models require no authorization, and FERRET can access them, for example,

yse? use "http://esgcet.llnl.gov/cgi-bin/dap-cgi.py/ipcc4/20c3m/gfdl_cm2_0/pcmdi.ipcc4.gfdl_cm2_0.20c3m.run1.ocn.mo.xml"
yse? show data
     currently SET data sets:
    1> http://esgcet.llnl.gov/cgi-bin/dap-cgi.py/ipcc4/20c3m/gfdl_cm2_0/pcmdi.ipcc4.gfdl_cm2_0.20c3m.run1.ocn.mo.xml (default)
name     title                             I         J         K         L
SO       Salinity                         1:360     1:200     1:50      1:1680
THETAO   Potential Temperature            1:360     1:200     1:50      1:1680

I intended to save a regional subset of the model output (the global data are too huge), and thought FERRET would do.

Thank you,
David

--

Peter Cornillon

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