Re: [netcdf-java] OPeNDAP authentication using nj22

Have you seen this doc:


If so, then I probably need to add more info to it. Let me know and I can look at it next week.

Jon Blower wrote:
Further information on this: I can connect successfully to the server
in question using the toolsUI-2.2.22.jar, but I still can't via my own
application.  I've had a quick look at the code for HttpClientManager
and HTTPRandomAccessFile and perhaps there is a call to
setDoAuthentication() missing?

Cheers, Jon

On Dec 13, 2007 9:12 PM, Jon Blower <jdb@xxxxxxxxxxxxxxxxxxxx> wrote:
Thanks John, and everyone else who replied.

I'm now experimenting with trying to get OPeNDAP authentication
working in version 2.2.22.  I have a very simple main() method that
simply tries to open a NetcdfDataset from an OPeNDAP URL, where the
OPeNDAP server requires authentication:

    public static void main(String[] args) throws Exception
        HttpClientManager.init(new CredentialsProvider(){
            public Credentials getCredentials(AuthScheme scheme,
                       String host, int port, boolean proxy)
                       throws CredentialsNotAvailableException
                System.out.println("Called Credentials Provider!");
                throw new CredentialsNotAvailableException();
        }, null);

        NetcdfDataset nc = NetcdfDataset.openDataset("http://myurl";);

When I run this I get an error message:

    Server does not support byte Ranges

which, having delved through the nj22 code, actually just means that
the call to get the value of the Accept-Ranges header does not return
what is expected.  I assume that the real reason that the call fails
is that the server requires authentication.  The simple
CredentialsProvider that I have written in the above code never gets

Could anyone please shed some light on this, or perhaps provide a code
snippet of the right way to go about this?

Thanks very much,

On Nov 26, 2007 7:24 PM, John Caron <caron@xxxxxxxxxxxxxxxx> wrote:
Hi Jon:

ucar.nc2.dataset.HttpClientManager is in 2.2.22 release. I beleive it was added 
at 2.2.19.

Jon Blower wrote:
Hi all,

I'm trying to read data from an authenticated OPeNDAP server.  I've
found the page,
which says that I should create a CredentialsProvider and register it
using ucar.nc2.dataset.HttpClientManager.init().  However, there is no
class called HttpClientManager in the ucar.nc2.dataset package, or
indeed anywhere in the nj22 distribution that I can see.

What is the best way to read data from authenticated OPeNDAP servers?
I am using nj22 version 2.2.16.

Thanks, Jon

Dr Jon Blower              Tel: +44 118 378 5213 (direct line)
Technical Director         Tel: +44 118 378 8741 (ESSC)
Reading e-Science Centre   Fax: +44 118 378 6413
ESSC                       Email: jdb@xxxxxxxxxxxxxxxxxxxx
University of Reading
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