Re: 20050204: ADDE on local host only

Hi Valentijn-

I apologize for the delay in responding.

Valentijn Venus wrote:

> Now that this ADDE datasource can successfully be accessed from a
McIDAS client using MCCOMPRESS=GZIP, i started experimenting with
accessing the same ADDE datasource from IDV. IDV sees the data, but when
requesting an image i get a progress bar with no progress showing. After
downloading and installing NCOMPRESS from the Fedora site (i'm running
Fedora Core 2) on the machine serving the ADDE data (and adding the path
of the binary to PATH in .mcenv, which now looks something like
PATH={MCGUI}:MCPATH:/usr/local/bin/), UNCOMPRESSed tranfers are also
working, but COMPRESSed tranfers still not. Because of that the McIDAS
client (in MCCOMPRESS=TRUE mode) nor IDV can see the data. I came across
the e-mail below, in which the new GZIP tranfers are discussed between
the two of you. Don, I read somewhere that IDV can only use COMPRESSed
tranfers. Is that true, or can IDV be equipped with the necessary
modules to support this new type of ADDE compression? Tom, what could be
wrong with my McIDAS config, since after i added the COMPRESS/UNCOMPRESS
program UNCOMPRESS seems to work fine, but COMPRESS not?

IDV supports compressed, gzip and uncompressed ADDE transfers.  By
default we use gzip compression for most of our adde access.
We recently found out the following:

- If you make a request for compressed data from a local machine,
the data does not come back compressed.  This was causing problems
in the IDV and is fixed in the latest visad.jar and will be included
in the next IDV release (next week).

For a particular server/dataset/descriptor, you can override the
default compression for image display.  This might help you
track down any problems.  To do this, you can create a file
imagedefaults.xml and place it in your ~/.metapps/DefaultIdv
directory.  The format would be:

<?xml version="1.0" encoding="UTF-8"?>
<imagedefaults>
  <default name="*" compress="gzip"/>
</imagedefaults>


For name, the valid values are of the form servername:group/descriptor.
An asterisk (*) can be substituted for any of positions and is the
default.

For name, you could use:

* = all servers
servername  - any image data on that server (same as servername:*/*)
servername:group  - all descriptors for a particular server/group
group/descriptor  - all datasets of this name on any server

for compress, the valid values are:

false  (no compression)
true or compress (compress transfers)
gzip   (gzip transfers)

This feature is used by the image chooser to define the ADDE properties.
Here's an example:

<?xml version="1.0" encoding="UTF-8"?>
<imagedefaults>
  <default name="*" debug="true"/>
  <default name="UPCCS02/nexrcomp" key="LATLON" enh="BREF24" 
place="CENTER" size ="800 800" loc="27.5 -81.5" mag="1 1" unit="ECHO"/>
  <default name="GINIEAST/GE1KVIS" key="LATLON" place="CENTER" 
size="800 800" loc="40 -105" mag="1 1" />
</imagedefaults>

Unfortunately, there is no documentation on all the parameters you
can use, yet.  This may undergo some changes in the near future to
support all our ADDE choosers, but for now it only works for the
image chooser.

Don
*************************************************************
Don Murray                               UCAR Unidata Program
address@hidden                        P.O. Box 3000
(303) 497-8628                              Boulder, CO 80307
http://www.unidata.ucar.edu/staff/donm
"There's someone in my head, but it's not me"    Roger Waters
*************************************************************