How would you implement a notification system in a monitoring tool?

To implement an alerting system in a monitoring tool, I would do the following:

1. Collect metrics and events — set up data collection using agents or APIs.
2. Define alerting rules — set threshold values or conditions under which notifications should be sent.
3. Process events — generate notifications when conditions are met.
4. Send notifications — integrate with communication channels: email, SMS, messengers (Slack, Telegram), push notifications.
5. Manage alert frequency — implement deduplication and rate limiting to avoid spam.

Example in pseudocode:

if metric.value > threshold:
    if not recently_alerted():
        send_notification(channel, message)
        update_last_alert_time()

It is also important to provide the ability to configure rules and notification channels via UI or configuration files.