Long Polling
Posted: | Tags: system-design, tech
Explanations of Long Polling start with the server “holds the connection open.”. To understand Long Polling, it helps to go one level lower than HTTP. Suppose a client wants to fetch messages. GET /messages The HTTP request is converted into bytes, passed to TCP, encapsulated into IP packets and sent over the network. Before any HTTP request is sent, TCP establishes a connection. Client Server SYN ----------------------> <------------------- SYN-ACK ACK ----------------------> Once this handshake completes, the client and server have an established TCP connection. Read more...