Server-Sent Events (SSE)

SSE allow a web page to get updates from a server. Unlike WebSockets, SSEs are unidirectional (Server -> Client) and use standard HTTP.

When to Use

• Live Feeds: News tickers, Sport scores, Stock prices.
• Progress Updates: "Processing Import: 45%...", Logging streams.
• Notifications: In-app alerts where the user doesn't need to reply instantly via the same channel.
• Replacement for Polling: More efficient than asking "Are we there yet?" every second.

Quick Start

// Client
const evtSource = new EventSource("/api/events");