SSE = Server-Sent Events It is a one-way real-time communication method where the server continuously pushes data to the browser over a single long-lived HTTP connection. Think of SSE as: Server → Browser (only one-way) live updates Not two-way like WebSockets. How SSE works (simple explanation) Browser opens a connection: Server keeps the connection open and keeps sending events: Browser receives them instantly as they come. Where SSE is used? Live notificationsChat message updates (receive only)Live counters, analyticsStock tickersLive logsNews feed updatesDashboard updates SSE vs WebSocket Feature SSE WebSocket Direction One-way (Server → Client) Two-way Transport HTTP TCP Reconnection Built-in automatic Must implement Binary data No Yes Simpler Yes More complex Example Server sends: Browser receives: Why choose SSE over WebSocket? SSE is better when: You only need server → browser updatesLightweight notificationsYou want automatic reconnectionYou want simpler code and less overheadAPI-driven architecture already uses HTTP

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What is SSE?

ICSM Computer 535 11 Dec 2025

Ask by ICSM Computer

Updated 11 Dec 2025

1 Answers

ICSM Computer 11 Dec 2025

SSE = Server-Sent Events

It is a one-way real-time communication method where the server continuously pushes data to the browser over a single long-lived HTTP connection.

Think of SSE as:

Server → Browser (only one-way) live updates

Not two-way like WebSockets.

How SSE works (simple explanation)

Browser opens a connection:

const es = new EventSource('/stream');

Server keeps the connection open and keeps sending events:

data: Hello user
data: New message arrived
data: Notification updated

Browser receives them instantly as they come.

Where SSE is used?

Live notifications
Chat message updates (receive only)
Live counters, analytics
Stock tickers
Live logs
News feed updates
Dashboard updates

SSE vs WebSocket

Feature	SSE	WebSocket
Direction	One-way (Server → Client)	Two-way
Transport	HTTP	TCP
Reconnection	Built-in automatic	Must implement
Binary data	No	Yes
Simpler	Yes	More complex

Example

Server sends:

data: New notification for user 123

Browser receives:

es.onmessage = (e) => console.log(e.data);

Why choose SSE over WebSocket?

SSE is better when:

You only need server → browser updates
Lightweight notifications
You want automatic reconnection
You want simpler code and less overhead
API-driven architecture already uses HTTP

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