How to send the messages actively from golang's websocket server to client

Question

I'm a newcomer for the golang and websocket.

I'm trying to write a websocket server which can send the messages actively to client once the handshake is done.

but my server will just only send the message to the client when got the request from the client.

Does anyone know how to implement this feature or where can I find the related answer for that?

Thank you so much.

the source code is as follows:

package main

import (
    "log"
    "net/http"
)

func handler(w http.ResponseWriter, req *http.Request) {
    w.Header().Set("Content-Type", "text/plain")
    w.Write([]byte("Hi, the handshake is completed.\n"))
    w.Write([]byte("Let's start to talk something.\n"))
}

func main() {
    http.HandleFunc("/", handler)
    log.Printf("Start to listen on 443.")
    err := http.ListenAndServeTLS(":443", "server.crt", "server.key", nil)
    log.Fatal(err)
}

Answer 1

Thanks you all for you both's help to answer me. and sorry for the very late reply here.

You both's answer is really helpful and I learn a lot.

Finally, I also find the simple way to achieve the same result without using the gorilla, here comes my code:

package main

import (
    "fmt"
    "log"
    "net/http"
    "golang.org/x/net/websocket"
)

func Echo(ws *websocket.Conn) {
    var err error
    msg := `Hi, the handshake it complete!`

    for {
        if err = websocket.Message.Send(ws, msg); err != nil {
            fmt.Println("Can't send")
        } else {
            fmt.Println("Sending")
        }
    }
}

func main() {
    http.Handle("/", websocket.Handler(Echo))

    if err := http.ListenAndServeTLS("10.10.10.10:1010", "server.crt", "server.key", nil); err != nil {
        log.Fatal("ListenAndServe:", err)
    }
}