sse's Introduction

sse

Server-Sent Events (SSE) library for Go.

See https://www.w3.org/TR/eventsource for the technical specification.

Features

Simple API.
Performant.
Dependency-free.
Low-level API to build a server.

Install

Go version 1.13

go get github.com/cristalhq/sse

Example

As a simple HTTP handler:

http.HandleFunc("/sse", func(w http.ResponseWriter, r *http.Request) {
    stream, err := sse.UpgradeHTTP(r, w)
    if err != nil {
        http.Error(w, err.Error(), http.StatusBadRequest)
        return
    }

    data := struct {
        Text string `json:"text"`
    }{
        Text: "hey there",
    }
    stream.WriteJSON("123", "msg", data)
})

See example_test.go for more.

Documentation

See these docs.

License

MIT License.

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sse's Issues

Can't close connection server-side

Hey, I want to close connection from server-side. Here is MRE:

package main

import (
	"fmt"
	"log"
	"net/http"

	"github.com/cristalhq/sse"
)

func main() {
	if err := http.ListenAndServe(":8080", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		stream, err := sse.UpgradeHTTP(r, w)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		defer func() { 
			if err := stream.Close(); err != nil {
				log.Printf("close stream error: %s", err)
			}
		}()

		for i := 0; i < 3; i++ {
			if err := stream.WriteEvent(
				0,
				"test",
				[]byte(fmt.Sprintf("payload %d", i)),
			); err != nil {
				log.Printf("write event error: %s", err)
			}
		}

	})); err != nil {
		log.Fatal(err)
	}
}

Output

2023/10/05 00:55:10 http: response.Write on hijacked connection from github.com/cristalhq/sse.(*Stream).Close (stream.go:31)
2023/10/05 00:55:10 close stream error: http: connection has been hijacked

I'll send out an PR soon.

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