NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
Also, the "Accept_Ranges" header is needed, details here: http://www.unidata.ucar.edu/software/netcdf-java/reference/HTTPservice.html On 10/11/2012 10:31 AM, Brian Schlining wrote:
Hi Bob, We're doing some work with ERDDAP and running into an issue using NetCDF-Java to access files served by ERDDAP. I think I understand the issue and know how to address it, so I'm passing the info onto you all so it can be addressed. So here goes: 1) ERDDAP allows one to download a NetCDF file by building a link appended with '.nc'. The link URL for the netcdf file would be something like http://beach.mbari.org:8180/erddap/griddap/erdRyanSST.nc. This works great for downloading the files. However, it does NOT work with the NetCDF-Java API; NetCDF-Java can normally read NetCDF files from arbitrary non-opendap http urls. 2) The reason it fails is because NetCDF-Java needs to know the size of the file being served. This requires that the HTTP response for a URL like http://beach.mbari.org:8180/erddap/griddap/erdRyanSST.nc to contain a 'Content-Length' field. ERDDAP is not sending that … here's a response header from ERDDAP (notice there's no 'Content-Length': HTTP/1.1 200 OK Server: Apache-Coyote/1.1 Date: Thu, 11 Oct 2012 15:44:19 GMT Last-Modified: Thu, 11 Oct 2012 15:44:19 GMT xdods-server: dods/3.7 erddap-server: 1.38 Content-Disposition: attachment;filename=erdRyanSST_8571_f367_229e.nc Content-Encoding: Content-Type: application/x-download Transfer-Encoding: chunked 3) Since ERDDAP is running on Tomcat, the only way I know of to set the 'Content-Length' is to explicitly call 'response.setBufferSize()' in the servlet that returns the NetCDF file. Note that once the response size goes beyond the bufferSize, Tomcat will fallback to 'Transfer-Encoding: Chunked' (which we don't want). So make sure you're setting the buffer size to the correct value. Hope that helps! p.s. I cc'd this to the netcdf-java mailing list in case I got something wrong. Hopefully someone will correct me. Cheers -- B ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Brian Schlining MBARI Software Engineer, Research and Development brian@xxxxxxxxx <mailto:brian@xxxxxxxxx> (831) 775-1855 http://www.mbari.org/staff/brian _______________________________________________ netcdf-java mailing list netcdf-java@xxxxxxxxxxxxxxxx For list information or to unsubscribe, visit: http://www.unidata.ucar.edu/mailing_lists/
netcdf-java archives: