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Difference between Long Polling and Websocket
Long Polling and WebSocket are both technologies used for real−time data transfer between a client and a server. They provide a way for the client to receive updates from the server in real−time, allowing for more interactive and responsive web applications. The main difference between them is that long polling sends the request to the client or receiver and waits until a response is received which means one−way communication. On the other hand, WebSockets are used to send the data in both directions simultaneously.
What is Long Polling?
In long polling, until it has information to send back to the client, the server keeps the connection active. This enables real−time updates without the client having to make repeated requests to the server. This technology is convenient and supported on all web browsers. This means that if the connection between the client and server is lost, it may not automatically reconnect.
The client sends a request to the host or transmitter and waits for a response. The server keeps the connection open until it has data to send back to the client. Once the client receives the response, it sends another request to the server and the process repeats.
Advantages of the Long Polling Technique
It works well for small−scale tasks and is simple to implement.
It is almost always assisted by gadgets.
To determine the status of its requests, the browser need not submit repeated inquiries.
Since it does not make repeated queries to a server, which wastes resources, it is more effective than the original polling strategy.
Disadvantages of Long Polling Technique
It uses more server resources than a WebSocket connection.
Because there are several hops between servers and devices, there may be latency overhead.
Long polling can have problems with reliable message ordering because it is possible for one client to simultaneously send several HTTP requests.
If the same client makes several connections to the server, message ordering cannot be ensured. There may have been a message loss if the client was unable to receive the message.
What is Websocket?
A client and a server can communicate in both directions using the WebSocket protocol. In other words, data can be delivered and received simultaneously without requiring further HTTP requests. A WebSocket connection that has been formed stays active until it is closed by the client or the server. Real−time data transfer is made possible, and the client no longer needs to make requests to the server regularly.
Packets of data are used to transport data between the client and server. These packets can be sent in either direction and can contain any kind of data. As a result, communication between the client and server is effective and real−time.
Advantages of Websocket
It enables two−way communication, which enables simultaneous data transmission and reception.
We can forward and deliver data more quickly with WebSocket as compared to HTTP.
WebSocket allows for inter−origin communication, but there are security problems associated with this.
Because WebSocket has less overhead than HTTP, it is more effective. While WebSocket only uses 2 bytes of overhead, HTTP can use up to 2000 bytes.
Disadvantages of Websocket
Compared to HTTP, cache storage between client and server is not possible with WebSocket.
HTTP is significantly easier to develop if the application does not require a lot of dynamic interaction.
Difference between Long Polling and Websocket:
Basic Parameters |
Long Polling |
Websocket |
|---|---|---|
Communication |
Only one way of data transmission is possible at once and is called Half−duplex |
But data can be sent in both directions called Full−duplex. |
Connection |
Long Polling uses multiple HTTP connections to send and receive data. |
WebSocket uses a single TCP connection to send and receive data |
Data transfer |
With Long Polling, data would be sent from the server to the respective client with the need for a client request |
With WebSocket, data can be sent by the server to the respective client at any time without the need for a client request. |
Latency |
Long Polling has a higher delay due to the need for multiple HTTP requests to send and receive data. |
WebSocket has a lower delay due to the use of a single TCP connection. |
Resource usage |
It is more resource−intensive on the server than WebSocket because it requires multiple HTTP connections. |
It is less resource−intensive on the server because it uses a single TCP connection. |
Browser support |
Long Polling is supported by all web browsers. |
WebSocket requires a modern web browser with HTML5 support. |
Conclusion
Long polling and WebSockets are used to share or send data between two devices or from transmitter to receiver efficiently. One of the real−time applications that use the WebSockets is WhatsApp and Telegram, and because of this, the timely delivery of messages is possible.
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