Espresso comprises a suite of python scripts to assist in disk based
correlation with DiFX.

To set up you need to carry out a few steps.

1) Edit the cluster definition file (see corr_hosts.txt for an example) to
contain a list of all your cluster nodes. Indicate the areas where baseband
data may be stored on those nodes.

2) Ensure the following two environment variables are set. $DIFX_MACHINES
should point to your version of the corr_hosts.txt file and $CORR_DATA should
point to the data area where you want the correlator output data to end up. Add
these to your .bashrc or similar:

export DIFX_MACHINES=/home/corr/corr_hosts.txt
export CORR_DATA=/data/corr/corrdat/

3) Run the install script:
./install.py $DIFXROOT

this will simply copy the python scripts to your DiFX installation's bin
directory.

4) The system will force you to enter a comment before and after every
correlation run. By default it will open vim to let you enter the comment. If
you prefer to use another editor then set the $EDITOR environment variable.

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Part of espresso's job is to find and sort the baseband data on your cluster.
To enable this you must bear a couple of things in mind.

1) The root of the data storage areas is defined in the $DIFX_MACHINES file.
Any baseband data should be stored in a subdirectory of one of the data areas
defined there.

2) When loading the baseband data, data from each telescope should be stored in
its own directory. The directory name should follow the format <exp>-<tel>
where <exp> is the experiment name, and <tel> is the telescope name (as given
in the .v2d file). An example directory name would be:

v289b-At

for telescope AT (ATCA) in experiment v289b.

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For more information on the full suite of scripts, see the documentation on the DiFX wiki: http://www.atnf.csiro.au/vlbi/dokuwiki/doku.php/difx/espresso

Bugs and feature requests should be sent to Cormac Reynolds
(cormac.reynolds@csiro.au) or submitted to the DiFX 'trac' bug tracking tool.