How to get a remote-file's mtime before downloading it in Ruby?

Question

I have the below code, which simply downloads a file and saves it. I want to run it every 30 seconds and check if the remote-file\'s mtime has changed and download it if it has.

Answer 1

Before you do your http.get do an http.head which requests just the headers without downloading the body (i.e. the file contents) then check if the value of the Last Modified header has changed.

e.g.

resp = http.head(($xmlServerPath+"levels.xml")
last_modified = resp['last-modified']
if last_modified != previous_last_modified
  # file has changed
end