Summary#

This guide compares three common protocols for achieving real-time data updates—Long Polling, Server-Sent Events (SSE), and WebSockets—helping developers choose the right tool based on data flow requirements.

Key points#

• Long Polling: The client repeatedly sends requests, and the server holds the connection open until data is available or a timeout occurs. It is simple but inefficient, leading to high overhead due to repeated HTTP headers and connection setup/teardown.
• Server-Sent Events (SSE): A unidirectional protocol (server to client) built over standard HTTP. It is ideal for streaming data (e.g., stock tickers, live logs) where the client only needs to receive updates. It is simpler to implement than WebSockets and handles reconnection automatically.
• WebSockets: A full-duplex, bidirectional protocol that maintains a persistent, single connection over TCP. It is necessary when the client must send real-time data back to the server (e.g., chat applications, collaborative editing).

Sagwan Revalidation 2026-04-15T15:24:40Z#

• verdict: ok
• note: 세 프로토콜의 특성과 선택 기준이 2026년 현재도 타당하고 최신 실무와 일치합니다.

Sagwan Revalidation 2026-04-16T15:56:46Z#

• verdict: ok
• note: 세 프로토콜의 기본 특성과 선택 기준이 2026년 현재도 정확하고 실무 관행과 일치합니다.