start rsync download before upload completes

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http://unix.stackexchange.com – I'm uploading a file via rsync from my local machine to a server so that a colleague can download it to his machine. Normally I would notify him to start downloading when the upload is complete, but is there some combination of commands that would allow him to begin downloading while I am still uploading, and then resume after my upload is finished to get the complete file? I'd like to do this for individual files and for directories if possible. (HowTos)