WebSocket vs Long Polling: Which is the Best for Real-time Web Applications?

Real-time web applications have become increasingly popular in recent years due to their ability to provide users with instant updates and interactions without the need for page refreshes. Two popular technologies used in developing real-time web applications are WebSocket and Long Polling. While both options are effective, there are some differences between them that make one more suitable for specific use cases than the other.

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What are WebSocket and Long Polling?

WebSocket and Long Polling are two different technologies used for real-time web applications. WebSocket is a protocol that allows two-way communication between a client and a server over a single, long-lived connection. Long Polling, on the other hand, is a technique that mimics real-time communication by repeatedly sending requests to the server and waiting for a response until new data is available.

WebSocket: How it Works

WebSocket uses a persistent connection between the client and the server, allowing for real-time communication without the need for repeated requests. The WebSocket protocol works by establishing a handshake between the client and the server, after which data can be sent bidirectionally between the two endpoints.

When a WebSocket connection is initiated, the client sends an opening handshake request to the server. If the server agrees to the connection, it responds with a handshake response that confirms the connection has been established. Once the connection is established, the client and server can send data to each other in real-time, without the need for repeated requests.

WebSocket is particularly useful for applications that require a high volume of real-time data, such as stock market tracking or online gaming. This is because WebSocket can handle a significant amount of traffic without overloading the server, thanks to its ability to maintain a persistent connection.

Long Polling: How it Works

Long Polling, as previously mentioned, mimics real-time communication by repeatedly sending requests to the server for new data. When a client initiates a Long Polling request, the server holds the request open until new data becomes available. Once new data is available, the server responds to the client’s request with the new data, and the client initiates another request.

Long Polling is useful for applications that require real-time data updates but don’t require a high volume of data to be transferred. For example, a chat application would benefit from Long Polling as it requires real-time updates but doesn’t transfer large amounts of data.

WebSocket vs Long Polling: Comparison

Latency

WebSocket has a lower latency than Long Polling as it maintains a persistent connection between the client and the server. This means that data can be sent and received in real-time, without the need for repeated requests. Long Polling, on the other hand, can have a higher latency as it requires repeated requests to the server for new data.

Bandwidth

WebSocket is more bandwidth-efficient than Long Polling as it only sends data when new data is available. Long Polling, on the other hand, can have higher bandwidth usage as it requires repeated requests to the server for new data, even if there is no new data available.

Scalability

WebSocket is highly scalable as it can handle a high volume of real-time data without overloading the server. Long Polling, on the other hand, can be less scalable as it requires repeated requests to the server, which can overload the server if there are too many clients making requests at the same time.

Browser Compatibility

WebSocket is not supported by all browsers, particularly older browsers. However, there are fallback options available that allow WebSocket to work on most browsers. Long Polling, on the other hand, is supported by all browsers that support AJAX.

FAQs

What is the difference between WebSocket and Long Polling?

WebSocket and Long Polling are two different technologies used for real-time web applications. WebSocket uses a persistent connection between the client and the server, allowing for real-time communication without the need for repeated requests. Long Polling, on the other hand, mimics real-time communication by repeatedly sending requests to the server and waiting for a response until new data is available.

When should I use WebSocket?

When should I use Long Polling?

Is WebSocket better than Long Polling?

WebSocket and Long Polling are both effective technologies for real-time web applications, but the best option depends on the specific use case. WebSocket is better suited for applications that require a high volume of real-time data, while Long Polling is better for applications that require real-time updates but don’t transfer large amounts of data.

What is the disadvantage of using WebSocket?

WebSocket is not supported by all browsers, particularly older browsers. However, there are fallback options available that allow WebSocket to work on most browsers.

What is the disadvantage of using Long Polling?

Long Polling can have higher latency and higher bandwidth usage than WebSocket as it requires repeated requests to the server for new data.

Conclusion

WebSocket and Long Polling are two effective technologies for real-time web applications, each with its own advantages and disadvantages. WebSocket is better suited for applications that require a high volume of real-time data, while Long Polling is better for applications that require real-time updates but don’t transfer large amounts of data. The best option for a specific use case depends on the specific requirements of the application.