add a raw gorilla websocket example

_examples/README.md

@@ -172,6 +172,7 @@
         * [BoltDB](sessions/database/boltdb/main.go)
         * [Redis](sessions/database/redis/main.go)
 * Websocket
+    * [Gorilla FileWatch (3rd-party)](websocket/gorilla-filewatch/main.go)
     * [Basic](websocket/basic)
         * [Server](websocket/basic/server.go)
         * [Go Client](websocket/basic/go-client/client.go)

_examples/websocket/gorilla-filewatch/go.mod

@@ -0,0 +1,10 @@
+module gorilla-filewatch-example
+
+go 1.14
+
+require (
+	github.com/gorilla/websocket v1.4.2
+	github.com/kataras/iris/v12 v12.1.8
+)
+
+replace github.com/kataras/iris/v12 => ../../../

_examples/websocket/gorilla-filewatch/main.go

@@ -0,0 +1,168 @@
+// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+//
+// This example shows a use case with gorilla webscokets package
+// sends a file to the browser client for display whenever the file is modified.
+//
+// $ go run main.go <name of file to watch>
+// # Open http://localhost:8080/ .
+// # Modify the file to see it update in the browser.
+package main
+
+import (
+	"flag"
+	"io/ioutil"
+	"log"
+	"os"
+	"strconv"
+	"time"
+
+	"github.com/gorilla/websocket"
+	"github.com/kataras/iris/v12"
+)
+
+const (
+	// Time allowed to write the file to the client.
+	writeWait = 10 * time.Second
+
+	// Time allowed to read the next pong message from the client.
+	pongWait = 60 * time.Second
+
+	// Send pings to client with this period. Must be less than pongWait.
+	pingPeriod = (pongWait * 9) / 10
+
+	// Poll file for changes with this period.
+	filePeriod = 10 * time.Second
+)
+
+var (
+	addr     = flag.String("addr", ":8080", "http service address")
+	filename string
+	upgrader = websocket.Upgrader{
+		ReadBufferSize:  1024,
+		WriteBufferSize: 1024,
+	}
+)
+
+func readFileIfModified(lastMod time.Time) ([]byte, time.Time, error) {
+	fi, err := os.Stat(filename)
+	if err != nil {
+		return nil, lastMod, err
+	}
+	if !fi.ModTime().After(lastMod) {
+		return nil, lastMod, nil
+	}
+	p, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return nil, fi.ModTime(), err
+	}
+	return p, fi.ModTime(), nil
+}
+
+func reader(ws *websocket.Conn) {
+	defer ws.Close()
+	ws.SetReadLimit(512)
+	ws.SetReadDeadline(time.Now().Add(pongWait))
+	ws.SetPongHandler(func(string) error { ws.SetReadDeadline(time.Now().Add(pongWait)); return nil })
+	for {
+		_, _, err := ws.ReadMessage()
+		if err != nil {
+			break
+		}
+	}
+}
+
+func writer(ws *websocket.Conn, lastMod time.Time) {
+	lastError := ""
+	pingTicker := time.NewTicker(pingPeriod)
+	fileTicker := time.NewTicker(filePeriod)
+	defer func() {
+		pingTicker.Stop()
+		fileTicker.Stop()
+		ws.Close()
+	}()
+	for {
+		select {
+		case <-fileTicker.C:
+			var p []byte
+			var err error
+
+			p, lastMod, err = readFileIfModified(lastMod)
+
+			if err != nil {
+				if s := err.Error(); s != lastError {
+					lastError = s
+					p = []byte(lastError)
+				}
+			} else {
+				lastError = ""
+			}
+
+			if p != nil {
+				ws.SetWriteDeadline(time.Now().Add(writeWait))
+				if err := ws.WriteMessage(websocket.TextMessage, p); err != nil {
+					return
+				}
+			}
+		case <-pingTicker.C:
+			ws.SetWriteDeadline(time.Now().Add(writeWait))
+			if err := ws.WriteMessage(websocket.PingMessage, []byte{}); err != nil {
+				return
+			}
+		}
+	}
+}
+
+func serveWs(ctx iris.Context) {
+	ws, err := upgrader.Upgrade(ctx.ResponseWriter(), ctx.Request(), nil)
+	if err != nil {
+		if _, ok := err.(websocket.HandshakeError); !ok {
+			log.Println(err)
+		}
+		return
+	}
+
+	var lastMod time.Time
+	if n, err := strconv.ParseInt(ctx.FormValue("lastMod"), 16, 64); err == nil {
+		lastMod = time.Unix(0, n)
+	}
+
+	go writer(ws, lastMod)
+	reader(ws)
+}
+
+func serveHome(ctx iris.Context) {
+	p, lastMod, err := readFileIfModified(time.Time{})
+	if err != nil {
+		p = []byte(err.Error())
+		lastMod = time.Unix(0, 0)
+	}
+	var v = struct {
+		Host    string
+		Data    string
+		LastMod string
+	}{
+		ctx.Host(),
+		string(p),
+		strconv.FormatInt(lastMod.UnixNano(), 16),
+	}
+	ctx.View("home.html", v)
+}
+
+// $ go get github.com/gorilla/websocket
+// $ go run main.go testfile.txt
+func main() {
+	flag.Parse()
+	if flag.NArg() != 1 {
+		log.Fatal("filename not specified")
+	}
+	filename = flag.Args()[0]
+
+	app := iris.New()
+	app.RegisterView(iris.HTML("./views", ".html"))
+	app.Get("/", serveHome)
+	app.Any("/ws", serveWs)
+
+	app.Listen(*addr)
+}

_examples/websocket/gorilla-filewatch/testfile.txt

@@ -0,0 +1,4 @@
+Some Contents
+# you can edit this file locally
+# and http://localhost:8080
+# will render the new contents through the live websocket connection.

_examples/websocket/gorilla-filewatch/views/home.html

@@ -0,0 +1,22 @@
+<!DOCTYPE html>
+<html lang="en">
+    <head>
+        <title>WebSocket Example</title>
+    </head>
+    <body>
+        <pre id="fileData">{{.Data}}</pre>
+        <script type="text/javascript">
+            (function() {
+                var data = document.getElementById("fileData");
+                var conn = new WebSocket("ws://{{.Host}}/ws?lastMod={{.LastMod}}");
+                conn.onclose = function(evt) {
+                    data.textContent = 'Connection closed';
+                }
+                conn.onmessage = function(evt) {
+                    console.log('file updated');
+                    data.textContent = evt.data;
+                }
+            })();
+        </script>
+    </body>
+</html>