Understanding HTTP Polling

1. Introduction

HTTP Polling is a technique used in real-time communication where a client repeatedly requests data from a server at regular intervals. This lesson covers the key concepts, workings, and best practices of HTTP Polling.

2. What is HTTP Polling?

HTTP Polling is a method where a client makes periodic HTTP requests to a server to check for updates. Unlike WebSockets, which maintain a persistent connection, HTTP Polling involves opening a new connection for each request.

3. How HTTP Polling Works

The process of HTTP Polling involves several steps:

1. Client initiates a request to the server.
2. Server processes the request and checks for new data.
3. If new data is available, the server responds with the data; otherwise, it may respond with an empty response.
4. Client waits for a specified interval before sending another request.

function httpPolling(url, interval) {
    setInterval(() => {
        fetch(url)
            .then(response => response.json())
            .then(data => {
                console.log("Data received:", data);
            })
            .catch(error => console.error("Error fetching data:", error));
    }, interval);
}

// Start polling every 5 seconds
httpPolling('https://api.example.com/data', 5000);
            

4. Best Practices

To optimize HTTP Polling, consider the following best practices:

• Choose an appropriate polling interval to balance server load and data freshness.
• Implement exponential backoff to reduce request frequency during periods of no updates.
• Use HTTP status codes effectively to manage client requests.
• Consider using long polling or WebSockets for more efficient real-time communication.

5. FAQ