Notifications are a critical yet often overlooked part of many software applications As a developer or engineer, having a solid grasp of notifications can make or break your next interview That’s why I’ve put together this comprehensive guide on the most common and insightful notifications interview questions you’re likely to encounter.
Whether you’re interviewing for a front-end, back-end, full-stack, or mobile role – notifications will play a part This guide aims to cover all the bases, diving into technical specifics while also exploring high-level strategy and design Let’s level up your notifications knowledge!
Why Notifications Matter
Before jumping into the specific questions, it’s worth stepping back and understanding why notifications have become such a vital component in apps and websites.
Notifications provide a channel for apps to connect with users even when they aren’t directly using the app. They allow us to send timely and relevant information to users that may impact their experience. For example, a messaging app can use notifications to alert users of new incoming messages. Or a shopping app may use notifications to remind users of items still in their cart.
Done well, notifications enhance user engagement But done poorly, they quickly become annoying. That’s why thinking through notification strategy and implementation is key
Common Notification Interview Questions
Now let’s explore some of the most frequently asked interview questions on notifications:
Q1: What are the main principles for designing effective notifications?
This question tests your understanding of the nuances involved in crafting good notifications. Here are some key principles to highlight:
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Relevance – Notifications should be timely, personalized and related to a user’s interests or needs. Don’t spam or blast irrelevant updates.
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Actionability – Include a clear call-to-action when appropriate so users know how to engage with the notification.
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Brevity – Be concise. Include only essential details and avoid lengthy blocks of text.
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Consistency – Adhere to platform-specific guidelines for visual design and writing style.
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Controllability – Give users options to control frequency, delivery method and types of notifications.
Q2: How are push notifications different from pull notifications?
This is a common technical question testing your knowledge of the two main notification delivery models:
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Push notifications are initiated by the server, sending information to users whether or not the app is open. This allows for real-time delivery of updates.
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Pull notifications require the client app to retrieve information from the server at periodic intervals, rather than the server pushing it. This approach uses fewer resources but isn’t instant.
Use cases and technical implementation differ between the two models.
Q3: Explain the architecture for push notifications
Since push notifications are a frequent technical topic, interviewers may ask you to explain the underlying architecture:
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The app server triggers the process by sending a notification request to a Push Notification Service (PNS) like Firebase Cloud Messaging.
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The request contains key information like the recipient device token and notification payload.
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The PNS routes the notification to the correct device using the token mapping.
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Client app receives notification payload, decrypts it and displays alert to user.
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SDKs and protocols like APNs facilitate communication between the components.
Q4: How do you handle notifications for inactive or offline users?
Apps need to account for users being offline when notifications are sent. Here are some strategies:
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Queuing: Store notifications in a queue to be sent when device comes online.
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Syncing: If needed, sync notifications across devices so user gets it on active device.
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Expiry: Set a Time-To-Live for notifications in queue and discard if expired.
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Persistence: For critical notices, persist notification by saving into local storage until user becomes active.
Q5: How would you optimize notification delivery for performance?
Since notifications need to reach users in a timely manner, performance is critical. Some optimization tips:
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Use a CDN to distribute notification traffic globally.
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Scale horizontally with load balancing across notification servers.
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Limit payload size to only essential data.
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Throttle requests to avoid overwhelming providers like APNs.
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Batch notifications during low-traffic periods if immediacy isn’t required.
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Profile to identify and improve bottlenecks.
Q6: What are some best practices for mobile notifications?
Mobile has its own nuances when it comes to notifications. Here are some mobile-specific best practices:
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Follow platform guidelines for visuals and behavior – iOS Human Interface Guidelines or Android Design Principles.
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Allow granular notification preferences by type, app section, etc.
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Use notification channels on Android Oreo and above.
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Sync notification state across devices, especially on iOS.
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Consider interactive notifications and remote input.
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Tailor notifications based on contextual data like time of day, user location, activity etc.
Q7: How would you avoid annoying users with notifications?
Interviewers want to see that you understand the risks of notification fatigue:
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Allow users to easily adjust notification frequency and types.
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Never force users to enable notifications. Make them optional.
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Use context like time of day, usage patterns and preferences to send appropriate notifications.
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Minimize disruptive notifications and use quieter options like badges for low priority updates.
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Give user control including easy access to mute or turn off notifications.
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Analyze data on ignored notifications to continuously improve targeting and content.
Q8: What are some tools you have used for implementing notifications?
Be ready to discuss tools and services you’ve used for sending notifications:
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Firebase Cloud Messaging: Cross-platform push notifications for Android, iOS and web. Provides delivery, analytics etc.
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Pushover: API for sending notifications to iOS, Android and Desktop apps. Lets you build custom UIs.
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OneSignal: Free push notification service for both mobile and web apps. Provides rich analytics.
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Twilio Notifications: Scalable API for push notifications across platforms.
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Push.js: Javascript library for web push notifications.
Talk about integration experience, key capabilities and pros/cons of each service.
Demo Your Skills with Coding Challenges
In addition to the above questions, you may be given a coding challenge related to notifications. Some examples:
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Build a web app demo that implements browser push notifications using the Push API and service workers.
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Develop a simple API endpoint for sending push notifications to mobile devices.
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Create a module for queuing notifications locally when device is offline.
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Design a notifications manager class that allows registering and dispatching notifications in an iOS or Android app.
Being able to demonstrate your working knowledge by coding up a notification-related feature is a great way to stand out.
Summary
Notifications may seem like a minor detail, but mastering them displays your technical breadth and user awareness as a developer. Use this guide to brush up on the key aspects of notifications for your next interview. From high-level strategies to nuts-and-bolts implementation, you’ll be ready to tackle any notifications questions that come your way!
Have you worked with CloudKit? If so, can you describe a project where you utilized it?
Yes, I have worked with CloudKit in a previous project. It was a mobile app for a fitness company where users could log their workouts and nutrition.
We utilized CloudKit to store and synchronize user data across devices. This enabled users to seamlessly switch between their phone and tablet without losing their progress. Additionally, it allowed us to implement real-time updates and push notifications for new workouts or meal plans. As the user information we had was private, we made sure to use strong security measures like encryption and two-factor authentication.
The results were impressive. Users found it easier to stick to their fitness goals when they used our app, which increased our retention rate by 25%. The real-time updates also helped us connect with our users more, which led to a rise in daily active users. Overall, utilizing CloudKit was a great decision and helped us take our app to the next level.
How do you ensure that Push Notifications are delivered effectively and efficiently?
As an experienced iOS developer, I understand the importance of ensuring push notifications are delivered efficiently and effectively. To achieve this, I follow several best practices:
- Making Payloads Work Better: I use CloudKit to store and download content separately from the push notification itself to make sure that large payloads are delivered smoothly. This increases the efficiency of notifications by reducing their size.
- Testing: I put my push notifications through a lot of tests to make sure they work right. In order to make sure my notifications are sent on time, I use Xcode to simulate different network and environment conditions.
- Monitoring: I keep an eye on push notifications to see if there are any problems with delivery. To give you an example, if I see that the same notification keeps failing to deliver to some devices, I look into why and take steps to fix it.
- Tracking Metrics: I keep an eye on key performance indicators like the delivery rate, open rate, and conversion rate to learn more about how users act and make changes to my push notification strategy as needed. For instance, I might change how often or when notifications are sent to make them more useful.
- Thinking About What Users Want: I always remember that users have the final say on whether they want to get push notifications or not. To respect their choices, I make sure that my app’s notification settings are complete and easy to find. This allows users to customize their notification preferences as desired.
I have been able to get a high delivery rate for push notifications in the past by following these best practices. As an example, the delivery rate for my most recent project was over 2095%, and the open rate was over 2060%. These impressive results are a testament to the effectiveness of my push notification strategy.
Notification Service System Design Interview Question to handle Billions of users & Notifications
FAQ
How can sensitive data like contacts or access to the camera or other sensors be secured in the world of mobile apps?
How does a notification service work?
Let’s call them the publisher since they publish messages. The publishers will send requests to the notification service to send notification messages for them. The client’s request to the notification service will first hit the load balancer. The load balancer helps distribute load evenly across the notification system servers.
What is notification & why is it used?
What is notification and why it is used? Email notifications are used to send users email or notifications about specific activities in system, such as updates to incidents or change requests. How to call email script into notification?
What should a notification system look like?
The system should be able to prioritize notifications. OTPs are high priority messages while news feed updates may be lower priority. The system should be able to support Email, SMS and push notifications on mobile and web browser. It should be an isolated system that is easy to integrate into an existing system, such as Facebook or LinkedIn.
How do in-app notification handlers work?
The in-app notification handler will further contact a push notification vendor, such as Firebase to send out push notifications to the users. Check out the course Coderust: Hacking the Coding Interview for Facebook and Google coding interviews. Each handler will be in contact with different vendors.
