Depth resolution: Server-Sent Events (SSE) technical principles and applications

Server-Sent Events (SSE) is a system that allows servers to pass through HTTP The protocol sends the customer aniso-step to a real-time update technology. SSE, compared to the traditional Polling model (b) More resource-efficient; It is lighter and easier to achieve on the existing HTTP infrastructure than on the WebSockets, which is a two-way communication.

The core features of SSE

One-way communications: Only the server is supported in sending data to the client. This design is well suited to scenarios such as news notices, stock price updates, etc.
Automatic reconnection: Browser-end EventSource API will automatically attempt to re-establish the connection when the connection is accidentally interrupted, and the developer will not have to prepare a complex re-try logic.
Based on text: The data format that you transmit is usually a simple UTF-8 text that is easily debugged and viewed.
Event type support: Servers to assign event fields, to allow the client to target different types of events (e.g., message , update , error ) triggers a different treatment logic.

How can the common problems in real-time applications be addressed?

Scenario one: AI chat robots (such as ChatGPT) respond slowly. Modern AI interfaces usually use SSE to return stream data. If your page is waiting for AI A blank when generating a complete answer, probably because of the non-use of SSE (c) Gradual rendering. This tool helps you verify whether the backend is sent correctly data: Paragraph.

Scenario 2: Connections are frequently overtime or disconnected. Checks the timeout settings of your server or proxy (e.g. Nginx). You may need to keep SSE connected long enough proxy_read_timeout Set to a larger value and ensure that Cache-Control Yes no-cache 。

SSE vs WebSockets: What choice?

If you only need to be single-way (e.g., big screen, social media alerts) for your application, you can be a very good user of the Internet. SSE It is preferred because it is simpler and supports automatic reconnection. If you need a two-way interaction (e.g. multi-authored, real-time game), you should choose WebSockets 。