Well, why not use a database on the system your sending it from? That way, you can have a store of file names, then when you commit, or rollback, you can have md5 fields and date fields and if you made it or didn't you can re-upload or re-download the appropriate versions of the files... (assuming you have the other orignal files some where...)

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Zak
Pluralitas non est ponenda sine neccesitate - mysql's philosphy