package main
import (
"bufio"
"fmt"
"log"
"time"
"github.com/gofiber/fiber/v2"
"github.com/gofiber/fiber/v2/middleware/cors"
"github.com/valyala/fasthttp"
)
var index = []byte(`<!DOCTYPE html>
<html>
<body>
<h1>SSE Messages</h1>
<div id="result"></div>
<script>
if(typeof(EventSource) !== "undefined") {
var source = new EventSource("http://127.0.0.1:3000/sse");
source.onmessage = function(event) {
document.getElementById("result").innerHTML += event.data + "<br>";
};
} else {
document.getElementById("result").innerHTML = "Sorry, your browser does not support server-sent events...";
}
</script>
</body>
</html>
`)
func main() {
// Fiber instance
app := fiber.New()
// CORS for external resources
app.Use(cors.New(cors.Config{
AllowOrigins: "http://127.0.0.1,http://localhost",
AllowHeaders: "Cache-Control",
AllowCredentials: true,
}))
app.Get("/", func(c *fiber.Ctx) error {
c.Response().Header.SetContentType(fiber.MIMETextHTMLCharsetUTF8)
return c.Status(fiber.StatusOK).Send(index)
})
app.Get("/sse", func(c *fiber.Ctx) error {
c.Set("Content-Type", "text/event-stream")
c.Set("Cache-Control", "no-cache")
c.Set("Connection", "keep-alive")
c.Set("Transfer-Encoding", "chunked")
c.Status(fiber.StatusOK).Context().SetBodyStreamWriter(fasthttp.StreamWriter(func(w *bufio.Writer) {
fmt.Println("WRITER")
var i int
for {
i++
msg := fmt.Sprintf("%d - the time is %v", i, time.Now())
fmt.Fprintf(w, "data: Message: %s\n\n", msg)
fmt.Println(msg)
err := w.Flush()
if err != nil {
// Refreshing page in web browser will establish a new
// SSE connection, but only (the last) one is alive, so
// dead connections must be closed here.
fmt.Printf("Error while flushing: %v. Closing http connection.\n", err)
break
}
time.Sleep(2 * time.Second)
}
}))
return nil
})
// Start server
log.Fatal(app.Listen(":3000"))
}