Imagine a task: the user needs to receive a notification about an important event. Tell what main parts of work you see, what dependencies, risks, and how you will determine that the solution is suitable.

Main parts of a solution for notifying a user about an important event:

1. Event source — the component that generates the event (e.g., order status change).
2. Event processing system — a service that receives the event and decides to whom and how to send notifications.
3. Delivery channels — email, push notifications, SMS, etc.
4. State storage — to track which notifications have already been sent to avoid duplication.

Dependencies:

• Reliability of the event source.
• Availability of delivery channels.
• Correctness of user data (e.g., email).

Risks:

• Loss or duplication of notifications.
• Delivery delays.
• Incorrect event filtering.

How to determine if the solution is suitable:

• The user received the notification at the right time.
• No duplicate messages.
• The system is resilient to failures (e.g., messages are not lost if the notification service crashes).
• Delivery and response metrics meet the requirements.