服务器发送事件与 WebSockets
学习服务器发送事件如何提供单向实时流式传输，了解它们与 WebSockets 和长轮询的区别，以及何时选择每种技术。
服务器发送事件与 WebSockets 是 CoddyKit 上的免费 WebSockets & Real-Time Systems with Spring 课时。 这是第 4 节课，共 4 节。 你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。 这是 WebSockets & Real-Time Systems with Spring 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 WebSockets & Real-Time Systems with Spring 课程共包含 4 节课。
本课时的部分内容尚未翻译，以英文显示。
Another Real-Time Option
WebSockets are not the only option. Server-Sent Events (SSE) give a simpler, one-way streaming channel from server to client over plain HTTP.
What Are Server-Sent Events?
SSE pushes a continuous stream of text events to the browser over one long-lived HTTP connection, received via the EventSource API. It is one-way only.
The SSE Wire Format
SSE uses a simple, line-based wire format over the text/event-stream content type — just data: and optional event: fields.
HTTP/1.1 200 OK
Content-Type: text/event-stream
data: First update
event: price
data: {"symbol":"ACME","price":42}
Receiving Events in the Browser
The client subscribes with EventSource, and the browser automatically reconnects if the stream drops — no manual retry logic needed.
const source = new EventSource('/stream');
source.onmessage = function (e) {
console.log('message:', e.data);
};
source.addEventListener('price', function (e) {
console.log('price event:', e.data);
});Built-In Reconnection
SSE has reconnection built in: the server sets the delay with a retry: field, and the client sends Last-Event-ID to resume where it left off.
SSE vs WebSockets
SSE vs WebSockets: SSE is one-way over plain HTTP with auto-reconnect and text only; WebSockets are full-duplex, use their own protocol, and support binary.
SSE vs Long Polling
Versus long polling, SSE keeps one connection open and streams many events, avoiding the cost of reopening a connection for every message.
When to Use SSE
Reach for SSE for one-way feeds: live notifications, activity streams, stock tickers, dashboards, job progress, and live scores.
When to Use WebSockets
Choose WebSockets when the client sends frequently too: chat, multiplayer, collaborative editing. If you only need server-to-client, SSE is simpler.
Limitations of SSE
SSE has limits: text only, no binary; browsers cap connections per domain (eased by HTTP/2); and older environments may lack support.
A Decision Helper
A simple rule of thumb decides most cases — need client-to-server or binary? Pick WebSocket. Otherwise, SSE.
def choose_transport(needs_client_to_server, needs_binary):
if needs_client_to_server or needs_binary:
return 'WebSocket'
return 'Server-Sent Events'
print(choose_transport(False, False)) # notifications
print(choose_transport(True, False)) # chatQuick Check
One feed, one direction, one connection — how well do you know SSE?
Recap
You learned Server-Sent Events: simple one-way streaming over HTTP with auto-reconnect, how they compare to WebSockets and long polling, and when to use each.
用 AI 导师学习 WebSockets & Real-Time Systems with Spring — 免费
在浏览器中编写并运行真实代码，获得全天候 AI 导师的即时帮助，并在网页或应用中继续学习。
- 课程
- 12
- 课程
- 48
常见问题解答
「服务器发送事件与 WebSockets」课时是免费的吗？
是的 — 「服务器发送事件与 WebSockets」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 WebSockets & Real-Time Systems with Spring 课程的其余内容，请升级到 CoddyKit PRO。 WebSockets & Real-Time Systems with Spring 课程共包含 4 节课。
「服务器发送事件与 WebSockets」这节课中我会学到什么？
学习服务器发送事件如何提供单向实时流式传输，了解它们与 WebSockets 和长轮询的区别，以及何时选择每种技术。 你通过在浏览器中直接运行的动手代码来练习 WebSockets & Real-Time Systems with Spring，全天候 AI 导师会在你学习这节课的过程中回答你的问题。
学习 WebSockets & Real-Time Systems with Spring 需要有经验吗？
无需任何先前经验。CoddyKit 上的 WebSockets & Real-Time Systems with Spring 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。 这是第 4 节课，共 4 节。
「服务器发送事件与 WebSockets」课时需要多长时间？
大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。
我能在这节 WebSockets & Real-Time Systems with Spring 课中编写并运行代码吗？
能。每节 WebSockets & Real-Time Systems with Spring 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。
此课程中的所有课时
- 了解实时通信
- WebSockets 与 HTTP 轮询对比
- WebSocket 协议基础
- 服务器发送事件与 WebSockets