SSE

-unidriection

- over http

-build in browser support for reconnection

-still just looks like a look running HTTP request

-HTTP headers to indicate we will be sending in chunks

“SSE is a one-directional channel — server pushes events to the client over a single long-lived HTTP connection, but the client can’t send messages back over that same channel. It’s simpler than WebSocket: built on plain HTTP, auto-reconnects natively in the browser, and works through normal HTTP infrastructure (proxies, load balancers) without special handling.”

When to reach for it:

• Server needs to push updates to the client, but the client never needs to talk back over that channel (e.g., Ticketmaster’s waiting-queue position updates — server tells you your position, you don’t send anything back)
• You want something simpler and lighter-weight than WebSocket, and don’t need bidirectionality

Its weak spot: one-directional only — if the client ever needs to send data back in the same interaction, you’d need a separate regular HTTP request alongside it, or switch to WebSocket entirely.