Technical Information

How ClockWatch Works

The following is a summary of the steps ClockWatch performs when a time setting is made:

1. ClockWatch is started.

2. A time set is initiated by a Client:

User presses "Set Time" button
The alarm time set in the Once or Daily mode goes off.
The Auto mode calculation determines that the clock needs updating.

3. ClockWatch queries the timeserver specified by making a TCP/IP connection over the Internet or by dialing the timeserver directly.

4. The timeserver returns the exact standard time in NIST, Daytime, NTP or Time format.

5. ClockWatch checks to see that the string returned is valid. If an NIST server, it checks that the NIST server is healthy, and that the time delay from the NIST is in a tolerable range--within 150 milliseconds. It also calculates the round-trip response time of the timeserver over the Internet and adjusts the time accordingly.

6. ClockWatch converts standard time to local time and compares it to the internal system time on the computer. If NTP format, it also converts the fractional part of the second from timeserver.

7. If the time difference is within program thresholds, the time adjustment is made. A summary of the setting is written to the log file (if enabled).

8. If the clocks are in sync or there was an error, then the clock is not reset and the attempt is written to the log file.

9. ClockWatch returns to the previous mode before the setting, unless the mode was 'Once'.