Token-Based Push Notifications: How They Work and Why They Matter

In the bustling realm of mobile applications, the ability to engage users effectively is a paramount concern for developers and businesses alike. Push notifications have emerged as a powerful tool for maintaining user engagement and driving app usage. Central to the mechanics of push notifications is the concept of token-based communication, a sophisticated yet essential process that underpins the seamless delivery of messages to user devices.

Photo by Volodymyr Hryshchenko on Unsplash

Understanding Token-Based Push Notifications

Push notifications serve as a direct line of communication between mobile applications and their users. Unlike traditional forms of communication, such as emails or in-app messages, push notifications allow apps to reach users even when they are not actively engaged with the application. This real-time communication capability enables developers to deliver timely updates, alerts, promotions, and other relevant information directly to users’ devices.

At the core of token-based push notifications lies the generation and management of unique identifiers known as tokens. These tokens serve as virtual addresses, enabling the push notification service to route messages to specific devices accurately. The process of token-based push notifications unfolds through several key stages:

1. Device Registration

When a user installs an application and opts to receive push notifications, the app initiates a registration process with the designated push notification service, such as Apple’s APNs or Google’s FCM. During this registration, the app provides essential information about the device, including its operating system and unique identifiers.

2. Token Generation

The push notification service then uses this information to generate a unique token. The specific algorithm used to generate this token is proprietary to each service and is designed to ensure that each token is unique and secure. This typically involves some form of cryptographic hash function, which takes the input data (the device and app information) and produces a fixed-size string of bytes. The output is unique to the input data, meaning even a small change in the input will produce a significantly different output.

3. Token Storage

Following token generation, the application receives the unique token from the push notification service. Typically, the app transmits this token to its backend server, where it is securely stored along with other user-related data. This centralized token storage enables the server to maintain an up-to-date record of devices registered to receive push notifications.

4. Sending a Notification

When the need arises to send a push notification — be it for announcing new content, delivering messages, or promoting offers — the application server crafts the notification message and forwards it to the push notification service. Alongside the message, the server includes the relevant token identifying the target device.

5. Notification Delivery

Leveraging the token provided, the push notification service accurately routes the notification to the intended device. This process ensures precise delivery, regardless of the device’s location or current activity state.

6. Notification Receipt

Upon receipt, the device displays the push notification to the user, typically as a banner or alert. Users can then interact with the notification to access additional information or engage with the application directly.

How millions of notifications are sent?

Sending push notifications to millions of users is quite common for large-scale applications and services. This process is generally managed by the application’s server and the push notification service. Here’s a simplified version of how it works:

1. Segmentation and Personalization: First, the application’s server decides who should receive the notification. This could be all users, or a specific segment of users based on certain criteria (like location, user behavior, preferences, etc.). The server also decides what the notification should say, and it can personalize the message for each user if needed.
2. Batch Processing: The server doesn’t send a separate request for each user. Instead, it groups the tokens into batches. The size of these batches can vary, but they’re typically designed to balance efficiency and performance.
3. API Request: The server sends these batches to the push notification service via an API request. This request includes the tokens for all the devices in the batch and the notification content.
4. Queueing and Delivery: The push notification service receives the request and queues the notifications for delivery. It then works through this queue, sending the notification to each device in turn. This process is designed to be highly scalable, allowing the service to handle millions (or even billions) of notifications.
5. Feedback and Error Handling: The push notification service provides feedback on the success or failure of each notification. If a notification fails (for example, if a token is no longer valid), the server can take appropriate action, such as retrying the notification or updating the token.

This process is typically quite fast, allowing large numbers of notifications to be sent in a relatively short period. However, the exact speed can depend on various factors, including the capacity of the server, the performance of the push notification service, and the network conditions for each device.

Conclusion

Token-based push notifications represent a sophisticated yet essential mechanism for facilitating seamless communication between mobile applications and their users. By leveraging unique tokens and intricate backend processes, developers can deliver personalized, timely, and engaging messages directly to users’ devices. Understanding the intricacies of token-based push notifications empowers developers and businesses to harness the full potential of this powerful communication channel, driving user engagement and enhancing overall app experiences.