NO-Caching certain files with BIP

To answer your question, yes, the contains operator matches the compared text anywhere in the variable you're referencing. It is not, by default, case insensitive, though. For that, you'd need to use the tolower command.

when HTTP_REQUEST {
  set foundmatch 0
  if { [string tolower [HTTP::uri] ] contains "openmeetingversioncheck.swf" } {
  set foundmatch 1
  }
}
when HTTP_RESPONSE {
  if {$foundmatch == 1} {
    HTTP::header replace Cache-Control no-cache
    HTTP::header replace Pragma no-cache
  }
}

I'm not convinced this is your problem, though. Have you confirmed yet whether or not the headers are being replaced?

If you do a tcpdump on the interface that's sending the traffic back to the client, or on the client machine itself, you should be able to see whether or not the headers you're trying to modify are being replaced or not.

If they are, and you're still having an issue with the files being cached, then you'll likely need to research what else needs to be done to prevent this, if it's possible.

-Colin