Re: [netcdf-java] Possibility for per-dataset http client?

• To: Jon Blower <j.d.blower@xxxxxxxxxxxxx>
• Subject: Re: [netcdf-java] Possibility for per-dataset http client?
• From: John Caron <caron@xxxxxxxxxxxxxxxx>
• Date: Mon, 19 Jan 2009 09:46:45 -0700

Hi Jon:

Are you managing a database of user/password credentials for the various remote 
sites? 

Another design is that ncWMS has a single logon to each of your remote sites. 
Give each remote site a role, and manage access to them through standard 
role-based tomcat authentication, ie users are given that role if they have 
authorization. 

I have some more thoughts about what to do if that doesnt work.

John



Jon Blower wrote:
> Hi,
> 
> Accessing OPeNDAP or remote NetCDF files in nj4.0 uses the Apache
> Commons HttpClient library.  If my understanding is correct then nj4.0
> uses the same HttpClient instance for all connections, and this
> instance is set with static methods:
> 
>         opendap.dap.DConnect2.setHttpClient(client);
>         ucar.unidata.io.http.HTTPRandomAccessFile.setHttpClient(client);
> 
> In my case, I have a Java web application (running in a single VM)
> accessing lots of remote servers via HTTP.  The entire application
> uses the same HttpClient instance, and therefore there is no way to
> distinguish between the users of my application.  Say I have two users
> going via my application to the same secure OPeNDAP server.  My
> application can only associate a *single* username/password
> combination with the host:port of the OPeNDAP server, following the
> Credentials framework in HttpClient.  There is no way to register two
> different username/password combinations for the same remote server.
> 
> One possible way to fix this would be to allow each NetcdfDataset to
> be associated with its own HttpClient instance.  This could be
> provided as an optional parameter to openDataset(), defaulting back to
> the VM-wide one if omitted.  Then I could store an HttpClient (with
> associated credentials) in the user's session object in my
> application.  (I am not sure if this is good practice for HttpClient
> though.)
> 
> Is this easily remedied or a tough job?
> 
> Cheers, Jon
> 

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    • From: Jon Blower