Time-based routing (weekdayRange, dateRange, timeRange)
low
Time-based routing depends on the client's clock and timezone and on helper implementations that differ between engines in argument handling. Behaviour is hard to test and hard to reproduce in support cases.
Why it matters
weekdayRange("MON", "FRI") and timeRange(9, 17) are evaluated with the client’s local
time unless "GMT" is passed, so laptops in other timezones, wrong clocks and daylight
saving transitions change routing. The engines’ implementations also differ in details such
as accepted argument forms. The business need (different proxy outside office hours, a
maintenance window) is usually better served on the proxy side. Draft until the lab has
recorded the per-engine differences.
How to fix
Move time-dependent policy to the proxy; if the PAC must do it, pass "GMT" explicitly and test on every target engine.
Examples
Bad
function FindProxyForURL(url, host) {
if (weekdayRange("MON", "FRI") && timeRange(8, 18)) {
return "PROXY proxy.corp.example:8080";
}
return "PROXY backup.corp.example:8080";
}
Good
function FindProxyForURL(url, host) {
return "PROXY proxy.corp.example:8080; PROXY backup.corp.example:8080";
}