This document provides instructions on how one can mirror The Expert System for Thermodynamics ( http://www.thermofluids.net/ ) using the popular file transfer application rsync ( http://www.rsync.samba.org/ ).

Rsync is a tool that provides fast file transfer and synchronization capabilities. Using rsync, one can continuously maintain an equivalent distribution of software ("a mirror") on two or more systems across a network. Rsync synchronizes file sets using an optimal algorithm whereby only the differences between files are transmitted over the network.

Rsync can be used to maintain local installations of the The Expert System for Thermodynamics (TEST). To begin mirroring TEST, it is first necessary to download and install the rsync executable from (http://www.rsync.samba.org/ ). Binaries for a number of platforms are available via the following URL: http://rsync.samba.org/ftp/rsync/binaries/ . Once you have installed rsync on your system, send an e-mail to Professor Subrata Bhattacharjee (subrata@thermo.sdsu.edu ) requesting access to the TEST rsync server running on the system voyager4.sdsu.edu. Please include the IP address and fully qualified domain name (FQDN) of the system you will be using to run rsync. Once we receive your request to mirror TEST., we will configure our rsync server to permit mirroring from your site. When you receive e-mail confirmation that we have configured our rsync server, you can download a distribution of TEST for the first time using the command:

rsync -avz rsync://voyager4.sdsu.edu/TEST/ /path/to/hypertext/documents/TEST

where

/path/to/hypertext/documents

is the absolute path to your web server's hypertext document directory. The above command assumes that the rsync executable is in your search path. If you receive the error message

rsync: Command not found.

when you attempt to invoke rsync, precede the command with the absolute pathname to the location where you installed rsync. For example, if you installed rsync in a directory named /usr/freeware/bin, then you would invoke rsync as

/usr/freeware/bin/rsync -avz rsync://voyager4.sdsu.edu/TEST/ /path/to/hypertext/documents/TEST

Once rsync has completed transferring the initial distribution of TEST to your hypertext document directory, any subsequent invocations of the above rsync command will update your local copy with only those files that have changed since you last ran rsync.

To automate this process of keeping your local TEST mirror up-to-date, I recommend using the Unix clock daemon, cron. An example crontab entry to update TEST each morning at 2:30 AM would look similar to this:

#
# Synchronize local installation of The Expert System for Thermodynamics
#
30 02 * * * /usr/local/bin/rsync -avz rsync://voyager4.sdsu.edu/TEST/ \
            /usr/local/apache/htdocs/TEST

After you have successfully installed a local copy of TEST on your web server, verify that you can browse TEST using the URL to your local installation. For example if you installed TEST on a web-server system named www.sdsu.edu, the URL to the TEST distribution would be

http://www.sdsu.edu/TEST

If you have any questions please send me a note at subrata@thermo.sdsu.edu .