AJAX Long/Short Polling vs. WebSockets: When Should You Choose Which?

When to Choose AJAX Long/Short Polling over HTML5 WebSockets

In the realm of real-time web applications, AJAX long/short polling and HTML5 WebSockets are two popular techniques for retrieving data from a server in a timely manner. However, the advent of WebSockets raises questions about the relevance of AJAX long/short polling.

AJAX Long/Short Polling: Making the Most of HTTP

AJAX long/short polling involves repeatedly sending requests to a server to fetch new data. While long polling maintains an open connection for a longer duration, short polling sends requests more frequently. This method leverages the HTTP protocol and its browser support.

HTML5 WebSockets: A Direct and Persistent Connection

WebSockets, on the other hand, establish direct and persistent TCP connections between the client and server. This connection remains open until either party closes it. It enables bidirectional, real-time communication, unlike AJAX polling.

Choosing the Right Technique

While both techniques aim to address the challenge of retrieving data in a timely manner, their suitability depends on the specific application requirements.

Advantages of WebSockets:

• Near-instantaneous data transfer: WebSockets' persistent connection allows for almost immediate data exchange, making it ideal for applications that require fast and reliable updates.
• Bidirectional communication: Both client and server can send and receive data at any time, enabling a true real-time experience.
• Resource efficiency: WebSockets are more efficient than AJAX polling since they avoid the overhead of multiple HTTP requests.

Situations to Prefer AJAX Long/Short Polling:

Despite the advantages of WebSockets, there are still scenarios where AJAX polling remains preferred:

• Limited browser support: WebSockets are not supported by all browsers, especially older versions.
• Simple data retrieval: For applications with infrequent data updates and simple retrieval needs, AJAX polling may be a more practical choice.
• Compatibility with legacy systems: If an existing system relies heavily on HTTP requests, switching to WebSockets may require significant changes.

Conclusion

AJAX long/short polling and HTML5 WebSockets are both valuable techniques for retrieving data from a server in a timely manner. WebSockets offer significant advantages, particularly for applications that demand real-time communication. However, AJAX polling remains a suitable option for scenarios with specific constraints or where browser compatibility is a concern.

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