iCal — subscription and dynamic link

The iCal format (.ics) is the standard for sharing calendars between applications. Omniscol exposes each timetable (individual, class, classroom, teacher) as an iCal subscription link that the user can paste into Google Calendar, Apple Calendar, Outlook, Thunderbird or any other application that consumes standardized calendars.

Subscription link vs one-off export

Two very different uses:

• Subscription link (recommended) — an HTTPS URL pointing to Omniscol. The client application polls it regularly (hourly, daily depending on the client's settings) and keeps the user's calendar continuously up to date. When a lesson moves in Omniscol, the user sees it in their calendar without doing anything.
• One-off export — download of an .ics file at a given point in time. Handy for archiving, sharing by email, or feeding a system that cannot subscribe. But it is frozen: if the timetable changes, the file is not updated.

Prefer the subscription link when the end client is a modern application that can refresh a remote calendar (Google Calendar, Apple Calendar, Outlook).

Getting your subscription link

From the screens where sharing is available, the Sharing button opens a modal that can offer:

• one or more signed iCal subscription URLs,
• a "Copy URL" button,
• a QR code to scan,
• an .ics file download.

The URL contains a secret token: do not share it — anyone who obtains it can view the timetable covered by the link's scope until it expires or is invalidated.

Where to generate an iCal

The main entry points are:

• At the top of the Timetable module — the Sharing button can generate an iCal of all displayed timetables, a combined iCal that merges them into a single subscription, then the individual iCals. These links are bounded by the displayed school year.
• On each displayed timetable — the timetable's title bar gives access, on hover, to an atomic share for that timetable. The link covers the relevant school year.
• On a teacher's record — in Administration, the record's Sharing button generates the teacher's personal iCal, designed to remain valid over time as long as the link, the holding account and the chosen expiration allow it.
• When previewing a calendar timetable — in Timetable management, the preview's Sharing button generates the iCal of what is displayed, even if that timetable is not yet activated or published.

At each generation, the user can set an invalidation date. This date is encoded in the URL's token: it cannot be changed afterwards. To change the expiration, generate a new link.

Like the other share links, the iCal is also tied to the account that generated it: a password change, deactivation or deletion of the holding account invalidates the associated links.

Public link for a class or a classroom

The administrator can generate a subscription link for a class or a classroom (for example to share with parents or with an external service). These links are signed and carry an expiration date.

See also Share a timetable via a public link which describes the full set of sharing options (iCal, responsive web page, JSON via API).

Client-side setup

Google Calendar

1. In Google Calendar, on the left, next to Other calendars, click the + > From URL.
2. Paste the Omniscol subscription URL.
3. The calendar appears with an indicative label and a default color — both changeable.

Google refreshes the subscription roughly every 8-24 hours. Urgent changes: expect a delay.

Apple Calendar (macOS, iOS)

1. File > New Calendar Subscription.
2. Paste the Omniscol URL.

The Omniscol iCal link is set up for automatic refresh every half hour.

Outlook (Microsoft 365)

1. Add calendar > From Internet.
2. Paste the Omniscol URL.

Outlook updates at a rate that varies across versions; for older desktop versions, expect delays.

Limitations

• Client-side changes (moving an event in Google Calendar) are not propagated back to Omniscol — the subscription is read-only.
• The user must have an active Omniscol account to generate their personal URL.
• The link's expiration is written into the generated URL: it cannot be extended afterwards; generate a new link if needed.
• Events outside the timetable are included only if the share or the iCal filter includes them.