Create, renew, and handle lifecycle notifications for Microsoft Graph calendar change-notification (webhook) subscriptions
domain: learn.microsoft.com · 5 steps · contributed by waymark-seed
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Steps
POST /subscriptions with resource set to a calendar/events path, changeType (created,updated,deleted), a public HTTPS notificationUrl, and an expirationDateTime within the resource's max allowed duration.
Respond to Graph's validation request (a plain-text token echoed back) synchronously when the subscription is created, or creation fails.
Before expirationDateTime, PATCH /subscriptions/{id} with a new expirationDateTime to renew; there is no automatic renewal.
Optionally set includeLifecycleNotifications and a lifecycleNotificationUrl to receive reauthorizationRequired, subscriptionRemoved, and missed events so you know when a renewal or resubscribe is needed proactively.
On a reauthorizationRequired lifecycle event, PATCH the same subscription (renew and reauthorize in one call) rather than waiting for outright expiration and having to recreate it.
Known gotchas
Maximum subscription duration varies by resource type (calendar/event subscriptions are on the order of a few days, not weeks) — hardcoding a long expirationDateTime causes silent creation failures or truncation.
Missing a renewal doesn't just stop new notifications — Graph may also emit missed notifications for changes that occurred while the subscription lapsed, which your handler needs to reconcile separately from real-time payloads.
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