Apple Push Notification Service vs Google Cloud Messaging: What are the differences?

Key Differences between Apple Push Notification Service and Google Cloud Messaging

Apple Push Notification Service (APNS) and Google Cloud Messaging (GCM) are two popular platforms that allow developers to send push notifications to mobile devices. While both services provide similar functionality, there are several key differences between them.

1. Platform Compatibility: APNS is specifically designed for iOS devices, while GCM is primarily used for Android devices. This means that if you are targeting a specific operating system, you will need to use the corresponding service to send push notifications.

2. Registration Process: To send push notifications using APNS, developers need to obtain an SSL certificate and configure it on their server. On the other hand, GCM requires developers to register their application with the Firebase Cloud Messaging (FCM) platform, which involves obtaining an API key and configuring it in the application.

3. Payload Format: The payload format for push notifications is different between APNS and GCM. APNS requires the payload to be in JSON format, while GCM allows for both JSON and plain text payloads. This difference in payload format may require additional code changes when switching between the two services.

4. Message Routing: When sending push notifications using APNS, the messages are routed through Apple's servers to the target devices. In contrast, GCM uses Google's infrastructure to route messages. This difference in routing can have an impact on the delivery speed and reliability of push notifications.

5. Message Size Limit: APNS has a maximum payload size limit of 4 KB, while GCM allows for a larger payload size of up to 4 MB. This can be important when sending rich media or large amounts of data in push notifications.

6. Feedback Mechanism: APNS provides a feedback service that allows developers to receive information about the delivery status of push notifications. This feedback includes details such as the device token, timestamp, and whether the notification was successfully delivered. GCM, on the other hand, does not provide a built-in feedback mechanism, requiring developers to implement their own feedback system.

In summary, the key differences between APNS and GCM lie in their platform compatibility, registration process, payload format, message routing, message size limit, and feedback mechanism.