README.md

Send an alert when the temperature is below freezing point

Target: understanding policies and the process manager.

Edit and run alert-if-temperature-below-zero.php.

1. create a new WhenTemperatureBelowZeroSendAlert Policy
2. create a new SendTemperateBelowZeroAlert Command
3. create a new HandleSendTemperateBelowZeroAlert CommandHandler It should only print some alert message to STDERR via error_log(), for now.
4. wire it together with ProcessPolicies
5. run it, see if you can get the alerts fired

Question: what happens when you run the script multiple times? Question: what happens when new events appear, and you run the script again? Question: how should we deal with failures/crashes here?