Push notifications
If PUBLIC_URL is set, slotmirror asks Microsoft and Google to notify it when a calendar changes
that a rule reads or writes. A change then syncs within seconds.
Subscriptions
Section titled “Subscriptions”- Microsoft subscriptions last up to 7 days.
- Google channels last until Google ends them.
- The cron renews both a day before they expire.
When a notification is missed
Section titled “When a notification is missed”The cron runs every 10 minutes.
- Once an hour it runs a full cycle over all rules, as a check.
- In between, it runs only the rules whose source or target calendar has no active subscription.
A missed notification therefore costs at most an hour. Without PUBLIC_URL, every rule runs
every 10 minutes.
Security
Section titled “Security”Each notification carries a token that only your deployment can compute: an HMAC of the account
with SESSION_SECRET. Notifications without it change nothing.
If you rotate SESSION_SECRET, the existing subscriptions no longer match. They are created again
when they expire, which can take up to 7 days. The cron keeps syncing in the meantime.
Own writes
Section titled “Own writes”When slotmirror writes a block, Microsoft sends a notification for that write too. slotmirror recognises its own writes of the last two minutes and does not sync again for them. Google notifications carry no event IDs, so this filter works for Microsoft only.