OpenDAP https behind Proxy
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Hello,
I'm using Windows Matlab 2020b. I am attempting to read HTTPS OpenDAP data from matlab behind a proxy.
I can confirm with wget and my web browser that the proxy works for both http and https to the tds.hycom.org domain.
For Matlab, I've set HTTP_PROXY=proxy.mycompany.com:3129 and HTTPS_PROXY=proxy.mycompany.com:3129. I've done this from Windows 10's Settings => Edit Environment Variables for your account. After setting those variables I start a new matlab.
test HTTP, it works:
>> ncinfo('http://tds.hycom.org/thredds/dodsC/GLBy0.08/expt_93.0')
ans =
struct with fields:
Filename: 'http://tds.hycom.org/thredds/dodsC/GLBy0.08/expt_93.0'
Name: '/'
Dimensions: [1×4 struct]
Variables: [1×14 struct]
Attributes: [1×10 struct]
Groups: []
Format: 'classic'
test HTTPS, it fails:
>> ncinfo('https://tds.hycom.org/thredds/dodsC/GLBy0.08/expt_93.0');
Error using netcdflib
The NetCDF library encountered an error during execution of 'open' function - 'I/O failure
(NC_EIO)'. If the data source was an OPeNDAP URL, see the OPeNDAP Troubleshooting section in the
Users Guide.
Error in netcdf.open (line 67)
[varargout{:}] = netcdflib ( 'open', filename, varargin{1} );
Error in internal.matlab.imagesci.nc/openToRead (line 1278)
this.ncRootid = netcdf.open(this.Filename,'NOWRITE');
Error in internal.matlab.imagesci.nc (line 121)
this.openToRead();
Error in ncinfo (line 88)
ncObj = internal.matlab.imagesci.nc(ncFile);
My company's IT has confirmed that Matlab is making the request and getting a response from the server.
Is this a known limitation of the netcdf library matlab is using? Are there additional ways to get debugging information or understand the cause of the failure?
Related posts:
https://www.mathworks.com/matlabcentral/answers/223837-problem-to-access-opendap-data-behind-https-urls notes that no https access was available until ~2017.
https://www.mathworks.com/matlabcentral/answers/658718-problem-to-access-opendap-data-behind-https-urls notes that https didn't work for a particular URL in 2019b but a Mathworks Saff memeber notes that it works in 2020b (my version).
Thank you,
Luke
0 Comments
Answers (1)
daruzi
on 31 Mar 2021
>> ncinfo('https://tds.hycom.org/thredds/dodsC/GLBv0.08/expt_53.X/data/2006')
ans =
Filename: 'https://tds.hycom.org/thredds/dodsC/GLBv0.08/expt_53.X/data/2006'
Name: '/'
Dimensions: [1×4 struct]
Variables: [1×14 struct]
Attributes: [1×9 struct]
Groups: []
Format: 'classic'
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