[netcdf-java] extra http get request from toolsui.jar

• To: netcdf-java@xxxxxxxxxxxxxxxx
• Subject: [netcdf-java] extra http get request from toolsui.jar
• From: "fedor baart" <f.baart@xxxxxxxxx>
• Date: Tue, 11 Nov 2008 21:42:19 +0100

Hi,

I am working on a European project Micore for which I setup an opendap
server. I am experiencing some performance issues.

I tried using the toolsUI-2.2.22.jar with mexnc and matlab to access data
and noticed that for every request it takes about 10 seconds to call a
function.

Also when I used the toolsUI as a ui and tried using the ncdump function it
took about 10 seconds for it to return.

Using wireshark I stored the connection information which contains the
following information:

after 0.2 seconds:
 GET /opendap/rijkswaterstaat/jarkus/transect.nc.dds HTTP/1.1
returns after 0.21 seconds with HTTP OK and dimensions
after 0.22 seconds:
 GET /opendap/rijkswaterstaat/jarkus/transect.nc.das HTTP/1.1
returns after 0.23 seconds with HTTP OK and attributes
after 0.24 seconds:
GET /opendap/rijkswaterstaat/jarkus/transect.nc.dods?areaname,year HTTP/1.1
after 10 seconds returns with HTTP OK and a lot of data

So what happens:
0.25 seconds is spend enquiring the information needed for the ncdump
output.
10 seconds is spend on reading some variables, information which is not
needed

The site I tried this with is

http://micore.wldelft.nl/opendap/rijkswaterstaat/jarkus/transect.nc.html

I also found the same behaviour though with different variables on another
site I tried:
http://penguin.sfos.uaf.edu/opendap/FNMOC/sst/nc/200810/sst_2008102406.nc.bz2.html

toolsUI-4.0 gives the same results

Is anyone experiencing similar behaviour?
Can I assume this to be an error?
If it is an error in which source code (version 2.2.22 or 4.0 or svn?)
should it be fixed?
Can anyone suggest a way to speed up my queries to the opendap server if
this is expected behaviour?

Thanks,

Fedor Baart

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  • Re: [netcdf-java] extra http get request from toolsui.jar
    • From: fedor baart