Golang实践:Websocket
发布于 2019-08-12 · 本文总共 1693 字 · 阅读大约需要
5 分钟
HTTP协议的缺陷:通信只能由客户端发起; 如果服务器有连续的状态变化,客户端要获知就非常麻烦,只能使用”轮询”;
websocket是HTML5提供的一种浏览器与服务器进行全双工通讯的网络协议,支持服务器推送;
Websocket
历史
WebSocket协议在2008年诞生,2011年成为国际标准; 所有浏览器都已经支持;
特点
基于TCP传输协议,服务端实现简单;
复用HTTP握手通道,兼容性好;
双向平等对话,属于服务器推送技术的一种;
数据格式轻量、性能高效;
可以发送文本以及二进制数据;
Client发起连接,一旦确定Websocket通信连接,双方可直接向对方发送报文;
协议标识符是ws(如果加密,则为wss),服务器网址就是URL,ws://localhost:8081/echo
服务端示例
// websockets.go
package main
import (
"fmt"
"net/http"
"github.com/gorilla/websocket"
)
var upgrader = websocket.Upgrader{
ReadBufferSize: 1024,
WriteBufferSize: 1024,
}
func main() {
http.HandleFunc("/echo", func(w http.ResponseWriter, r *http.Request) {
conn, _ := upgrader.Upgrade(w, r, nil) // error ignored for sake of simplicity
for {
// Read message from browser
msgType, msg, err := conn.ReadMessage()
if err != nil {
return
}
// Print the message to the console
fmt.Printf("%s sent: %s\n", conn.RemoteAddr(), string(msg))
// Write message back to browser
if err = conn.WriteMessage(msgType, msg); err != nil {
return
}
}
})
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
http.ServeFile(w, r, "websockets.html")
})
http.ListenAndServe(":8080", nil)
}
websockets.html
<!-- websockets.html -->
<input id="input" type="text" />
<button onclick="send()">Send</button>
<pre id="output"></pre>
<script>
var input = document.getElementById("input");
var output = document.getElementById("output");
var socket = new WebSocket("ws://localhost:8080/echo");
socket.onopen = function () {
output.innerHTML += "Status: Connected\n";
};
socket.onmessage = function (e) {
output.innerHTML += "Server: " + e.data + "\n";
};
function send() {
socket.send(input.value);
input.value = "";
}
</script>
refs
https://flashphoner.com/7-ways-to-stream-rtsp-on-the-page/
https://tools.ietf.org/html/rfc6455
https://yalantis.com/blog/how-to-build-websockets-in-go/