Design a notification system in HLD - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to identify the main component responsible for sending notifications.

HLD

The component that sends notifications to users is called the [1].

Drag options to blanks, or click blank then click option'

ALoad Balancer

BUser Interface

CDatabase

DNotification Dispatcher

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing the database with the sender component.

The Notification Dispatcher is the main component that sends notifications to users.

2fill in blank

medium

Complete the code to specify the type of database best suited for storing user notification preferences.

HLD

For storing user notification preferences, a [1] database is preferred for fast key-value lookups.

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AGraph

BRelational

CKey-Value

DTime-Series

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing relational database which is less efficient here.

A Key-Value database is ideal for quick access to user preferences by user ID.

3fill in blank

hard

Fix the error in the notification delivery flow by selecting the correct component that handles retries.

HLD

If a notification fails to deliver, the [1] component retries sending it after a delay.

Drag options to blanks, or click blank then click option'

ARetry Service

BLoad Balancer

CUser Interface

DDatabase

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing load balancer with retry logic.

The Retry Service handles resending notifications that failed initially.

4fill in blank

hard

Fill both blanks to complete the notification system's architecture components.

HLD

The [1] queues incoming notifications, while the [2] sends them to users.

Drag options to blanks, or click blank then click option'

AMessage Broker

BUser Interface

CNotification Dispatcher

DDatabase

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up UI with sending component.

The Message Broker queues notifications, and the Notification Dispatcher sends them.

5fill in blank

hard

Fill all three blanks to complete the notification filtering logic.

HLD

Notifications are filtered by [1] before sending. The system checks [2] to respect user choices and uses [3] to avoid overload.

Drag options to blanks, or click blank then click option'

Apriority

Buser preferences

Crate limiting

Ddatabase

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing database with filtering logic.

Priority filters notifications, user preferences control delivery, and rate limiting prevents overload.