Two Ways to Push
Both Server Sent Events and WebSockets let a server send data to the browser without polling, but they differ in direction, transport, and simplicity.
Server Sent Events
SSE is a one way stream from server to client over a normal HTTP response that stays open. The browser exposes it through the EventSource interface.
- One direction only, server to client.
- Built in automatic reconnection and event IDs for resuming.
- Plain text over HTTP, easy to proxy and debug.
WebSockets
WebSockets are full duplex, so client and server both push at will, and they carry binary as easily as text. They need their own framing and you must implement reconnection yourself.
Picking One
Use SSE for live feeds, notifications, and dashboards where only the server pushes. Use WebSockets for chat, collaborative editing, and games that need low latency client to server messages too.
Key idea
SSE is a simple auto reconnecting one way stream over HTTP, while WebSockets add full duplex binary capable messaging at the cost of more complexity.