Network ProtocolLong Polling

Long polling is a technique used to achieve real-time data updates by sending requests at regular intervals. The key difference between long polling and other methods, such as short polling or websockets, is that with long polling the connection remains open until the server has data to send. This means that there is no need to continuously re-establish a connection, which can save on bandwidth and reduce latency.

Once the connection is established, the client will wait for a response from the server. If the server does not have any data to send immediately, it will hold the connection open until it does(or until a timeout is hit). As soon as new data is available, the server will push it out to the client and close the connection. The client will then immediately send another request to establish a new connection and begin listening for new data. This process repeats itself indefinitely, providing near-instantaneous updates to the client whenever new data is available.

Advantages and Disadvantages of Long Polling

Long polling has a few advantages over other real-time update methods. First, as mentioned above, it can reduce bandwidth usage and latency by eliminating the need to continuously re-establish connections. Second, it can be used with any type of web application without requiring any special infrastructure. Finally, it is relatively simple to implement and can be easily added to existing applications with minimal coding required.

On the downside, long polling can put extra strain on servers due to the number of open connections that need to be maintained. If connections are dropped or time out before receiving a response from the server, this can result in missed updates or delays in receiving new data. Long polling is not well suited for applications that require high frequency updates or large amounts of data to be transferred in real-time. For these types of applications, websockets or another push-based solution may be a better option.

Long polling is a useful technique for achieving real-time data updates in web applications without overburdening the system. It has some advantages over other methods, such as reduced latency and bandwidth usage, but also some disadvantages, such as potential strain on servers and missed updates if connections are dropped.