Long-polling vs Apple Push Notification Service & Android C2DM

Introduction

In the realm of real-time communication, ensuring timely delivery of updates is crucial. Traditionally, applications relied on polling mechanisms to check for new data. However, these methods were inefficient and resource-intensive. To address this challenge, long-polling and push notification services emerged as more efficient alternatives. This article delves into the differences between long-polling and push notification services, specifically focusing on Apple’s Push Notification Service (APNS) and Android’s Cloud to Device Messaging (C2DM).

Long-polling

Long-polling is a technique where the client maintains a persistent connection with the server, waiting for updates. Instead of repeatedly sending requests to the server (as in traditional polling), the client keeps the connection open until a new message arrives.

Advantages

• Simple implementation.
• Suitable for scenarios with infrequent updates.

Disadvantages

• High server load due to persistent connections.
• Inefficient for frequent updates as it keeps connections open even when there’s no data.
• Limited scalability, particularly for large numbers of clients.

Push Notification Services

Push notification services allow the server to push updates to clients proactively without the client needing to initiate a request. They leverage platform-specific mechanisms to deliver messages efficiently.

Advantages

• Low server load as connections are established only when there’s new data.
• Highly efficient for frequent updates.
• Excellent scalability due to the platform’s infrastructure handling connections.

Disadvantages

Apple Push Notification Service (APNS)

Apple’s Push Notification Service (APNS) enables developers to send notifications to iOS devices. APNS uses a dedicated protocol for communication between the server and the device.

Workflow

• The server connects to APNS and sends a notification request.
• APNS relays the notification to the target device.
• The device displays the notification to the user.

Code Example (Server-side – Python)

import apns

# Replace with your credentials
apns.configure(cert_file='path/to/cert.pem',
                 cert_env='sandbox')

# Send a notification
apns.send(apns.Payload(alert='Hello, World!'),
            apns.Token('your_device_token'))

Android Cloud to Device Messaging (C2DM)

Android’s Cloud to Device Messaging (C2DM), now known as Firebase Cloud Messaging (FCM), facilitates sending notifications to Android devices.

Workflow

• The server sends a notification request to Google’s FCM servers.
• FCM relays the notification to the target device.
• The device displays the notification to the user.

Code Example (Server-side – Java)

import com.google.firebase.messaging.FirebaseMessaging;
import com.google.firebase.messaging.Message;

// Replace with your project details
String token = "your_device_token";
String message = "Hello, World!";

// Create a message object
Message msg = Message.builder()
        .setToken(token)
        .setNotification(Notification.builder()
                .setTitle("FCM Notification")
                .setBody(message)
                .build())
        .build();

// Send the message
FirebaseMessaging.getInstance().send(msg);

Comparison Table

Conclusion

Long-polling and push notification services offer distinct approaches for real-time communication. Long-polling, while simple, is less efficient for frequent updates. Push notification services, such as APNS and C2DM (FCM), provide a more efficient and scalable solution. The choice between these technologies depends on specific application requirements, such as the frequency of updates, server resources, and platform support.