use a certificate. validation of valid-timerange is almost free. If your demo requires that the computer it runs on must be connected to the internet, you can use the certificate to connect to your own server. Then the time-range check is done on YOUR server and you can be sure that no clock-tweaking is done.
Otherwise ask yourself: what use is an application that does not represent the correct time? If you use a db: Check the timestamps. If you encounter a timestamp that is before another one already in the db... Then the computers clock has been changed... Now wait... a few moments in life, this can be regular (summer-time switching, adjusting a clock (not all server-clocks are correctly working all the time)), but still it can be an inidication, that something is going wrong. If you are really nervous about the clock-tweaking... why not write a special log-file where you use checksums to check for a correct log and put in the timestamp and check it that way for irregularities? hope this gives some ideas Alexander -----Original Message----- From: bOOyah [mailto:[EMAIL PROTECTED] Sent: Montag, 10. Mai 2004 15:27 To: [EMAIL PROTECTED] Subject: [OT] Any ideas for time-limiting demo web apps? Very off-topic this one, but I'm wondering if anyone has any good techniques for preventing a web app from working beyond a certain time? I'm thinking of the situation where demo or Beta versions of the app are distributed in the field and you want limit how long they will continue to work. Obviously I could check the system clock and perform a crude calculation. But how would I trap the system clock being reset back in time? Are there lightweight alternative techniques? TIA. -- bOOyah --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
