Comparison of TCP Long Connections and WebSocket

Nov 2, 2024#网络113

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TCP long connections are maintained in HTTP/1.1 by default, allowing persistent connections as long as requests are made within a specified timeout and limits are not exceeded. This reduces the overhead of repeatedly opening and closing connections compared to short connections. WebSocket is a bidirectional protocol based on TCP, established through an HTTP/1.1 handshake. After the handshake, communication occurs over TCP instead of HTTP. Key differences include: - WebSocket allows the server to send data to the client proactively, while TCP long connections require the client to initiate requests. - WebSocket maintains communication without needing to resend certain state information, whereas TCP long connections may need to include state information with each request.

TCP Long Connection#

HTTP/1.1 defaults to a long connection (Connection defaults to Keep-alive), so as long as requests are maintained within a specified time (timeout) and the server's and client's capacity limits are not reached, it can be maintained for a long time.

Compared to short connections, it simply lacks the open and close operations between multiple requests.

WebSocket Long Connection#

WebSocket is a bidirectional transmission protocol based on the TCP protocol, established through the HTTP/1.1 protocol's 101 status code handshake.

After the WebSocket handshake is established via the HTTP protocol, subsequent communication occurs through the TCP protocol instead of the HTTP protocol.

Differences#

Since WebSocket is a full-duplex protocol, the server can actively send data to the client, while a TCP long connection needs to wait for the client to initiate a request to respond.
WebSocket establishes a connection first and then maintains communication, allowing subsequent communication to omit some state information, while a TCP long connection may need to carry state information with each request.