24 votesZeno R.R. Davatz commented
Monitoring File sizes for WebServices that do File-Exports makes a lot of sense for a professional Business Software. If a file size changes above or below a certain threshold the users of the file should be alerted immediately via SMS, Email, Twitter, etc. If a file size changes more then 10% from one day to another then that is a certain sign that something is going on in the system.