See archive:Rsync for more details on how/why Rsync works.

On *nix systems

Command line

Graphical User Interface (GUI)

On Windows Systems

Use DeltaCopy for rsync'ing

Or use cwRsync. Click the download cwRsync button and the installer will create a batch file that will show up in your start menu. Once you run it will launch a command prompt where you use the same commands as are listed above:

rsync --progress --partial openmrs.org::builds/nightly/2008-02-14/openmrs.war openmrs.war

The trick to making sure that you get a nice speedup is making sure that you have an existing openmrs.war file in your current directory.