initial web server with websocket support.

.gcloudignore

+# This file specifies files that are *not* uploaded to Google Cloud Platform
+# using gcloud. It follows the same syntax as .gitignore, with the addition of
+# "#!include" directives (which insert the entries of the given .gitignore-style
+# file at that point).
+#
+# For more information, run:
+#   $ gcloud topic gcloudignore
+#
+.gcloudignore
+# If you would like to upload your .git directory, .gitignore file or files
+# from your .gitignore file, remove the corresponding line
+# below:
+.git
+.gitignore
+
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+# Test binary, build with `go test -c`
+*.test
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out

.idea/.gitignore

+# Default ignored files
+/shelf/
+/workspace.xml
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml
+# Editor-based HTTP Client requests
+/httpRequests/

.idea/goweb.iml

+<?xml version="1.0" encoding="UTF-8"?>
+<module type="WEB_MODULE" version="4">
+  <component name="Go" enabled="true" />
+  <component name="NewModuleRootManager">
+    <content url="file://$MODULE_DIR$" />
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

.idea/modules.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/.idea/goweb.iml" filepath="$PROJECT_DIR$/.idea/goweb.iml" />
+    </modules>
+  </component>
+</project>

.idea/vcs.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>

api1.go

+package main
+
+import (
+	"net/http"
+)
+
+const apiV1Prefix = "/api1/"
+
+func apiV1Main(http.ResponseWriter, *http.Request) {
+
+}

api1ws.go

+package main
+
+import (
+	"fmt"
+	"github.com/gorilla/websocket"
+	"log"
+	"net/http"
+)
+
+const apiV1WebSocket = apiV1Prefix + "ws"
+
+// We'll need to define an upgradeToWs
+// this will require a Read and Write buffer size
+var upgradeToWs = websocket.Upgrader{
+	ReadBufferSize:  1024,
+	WriteBufferSize: 1024,
+}
+
+func apiV1WebSocketHandler(w http.ResponseWriter, r *http.Request) {
+	upgradeToWs.CheckOrigin = func(r *http.Request) bool { return true }
+	ws, err := upgradeToWs.Upgrade(w, r, nil)
+	if err != nil {
+		log.Println("cannot upgrade websocket", err)
+		return
+	}
+
+	// helpful log statement to show connections
+	log.Println("Websocket Api/V1: Client Connected", r.RemoteAddr)
+
+	wsReader(ws)
+}
+
+func wsReader(conn *websocket.Conn) {
+	for {
+		// read in a message
+		messageType, p, err := conn.ReadMessage()
+		if err != nil {
+			log.Println(err)
+			return
+		}
+
+		WsEchoIncomingMessage(conn, string(p), messageType)
+		//switch messageType {
+		//case websocket.TextMessage:
+		//	WsProcessingTxtMessage(conn, string(p))
+		//	break
+		//case websocket.BinaryMessage:
+		//	WsProcessingBinaryMessage(conn, p)
+		//	break
+		//case websocket.PingMessage:
+		//	break
+		//case websocket.PongMessage:
+		//	break
+		//}
+	}
+}
+
+func WsEchoIncomingMessage(conn *websocket.Conn, msg string, messageType int) {
+	// print out that message for clarity
+	fmt.Println(msg)
+
+	// this is echo
+	if err := conn.WriteMessage(messageType, []byte(msg)); err != nil {
+		log.Println(err)
+		return
+	}
+}

app.yaml

+runtime: go115

config.go

+package main
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"log"
+)
+
+type configStaticHtml struct {
+	Dir         string
+	StaticUrl   string
+	StripPrefix string
+}
+
+type configuration struct {
+	Host    string
+	Port    string
+	DSN     string
+	TlsCert string
+	TlsKey  string
+	Static  []configStaticHtml
+	Debug   bool
+	TempDir string
+	Session struct { //TODO: figure what is this intended for
+		Guest bool
+		Year  int //how many years
+		Month int //how many years
+		Day   int //how many years
+	}
+}
+
+var configFile = "config.json"
+var config = configuration{}
+
+func (m *configuration) readConfig() (e error) {
+	log.Printf("read Path config from %s", configFile)
+	body, e := ioutil.ReadFile(configFile)
+	if e != nil {
+		log.Fatal("Cannot read config from " + configFile)
+		return
+	}
+	e = json.Unmarshal(body, m)
+
+	if config.Debug {
+		log.Println(config)
+	}
+	return
+}

config.json

+{
+  "Host":"0.0.0.0",
+  "Port":"8080",
+  "DSN": "sp:sp@tcp(192.168.1.70:3306)/syd_credit?parseTime=true&loc=Australia%2FSydney&collation=utf8mb4_0900_ai_ci",
+  "TlsCert": "fullchain.pem",
+  "TlsKey": "privkey.pem",
+  "Debug": true,
+  "Static": [
+    {
+      "Dir": "./html/",
+      "StaticUrl": "/",
+      "StripPrefix" : "/"
+    },
+    {
+      "Dir": "./html/test/",
+      "StaticUrl": "/spa1/",
+      "StripPrefix" : "/spa1/"
+    },
+    {
+      "Dir": "./html/test/",
+      "StaticUrl": "/spa2/",
+      "StripPrefix" : "/spa2/"
+    }
+  ],
+  "Session" : {
+    "Guest": true,
+    "Year": 10,
+    "Month": 1,
+    "Day": 1
+  }
+}

html/css/index.css

+p {
+    background-color:yellow;
+}
+
+h1 {
+    text-align: center;
+    text-decoration: #1ABC9C;
+}
+
+div {
+    width: 300px;
+    margin: auto;
+    text-align: left;
+}
+
+hr {
+    width: 100px;
+    border: 10px solid green;
+    border-radius: 5px;
+}
+
+li{
+    padding-bottom:15px;
+}

html/index.html

+<head>
+    <title>Demo static index</title>
+    <link rel="stylesheet" type="text/css" href="css/index.css">
+</head>
+<body>
+<h1> Static Html Site </h1>
+<hr>
+<div class="center">
+    <p >
+        This is a static website located on /
+    </p>
+
+    <ol>
+        <li>
+            <a href="css/index.css"> css/index.css </a>
+        </li>
+        <li>
+             static url <a href="spa1/"> /spa1 </a> &#x2192;  "./html/test/"
+        </li>
+        <li>
+             static url  <a href="spa2/">/spa2 </a> &#x2192; "./html/test/"
+        </li>
+        <li>
+            static url  <a href="test/">/test </a> &#x2192; "./html/test/"
+        </li>
+
+
+        <script>
+            let socket = new WebSocket("wss://svr2021.lawipac.com:8080/api/v1/ws");
+            console.log("Attempting Connection...");
+
+            socket.onopen = () => {
+                console.log("Successfully Connected");
+                socket.send("Hi From the Client!");
+                socket.send("send dummy string for 500 times"); //this is a special command server will respond;
+            };
+
+            socket.onclose = event => {
+                console.log("Socket Closed Connection: ", event);
+                socket.send("Client Closed!")
+            };
+
+            socket.onerror = error => {
+                console.log("Socket Error: ", error);
+            };
+
+            socket.onmessage = e => {
+                if(typeof e.data != "string" ) {
+                    console.log("invalid data received ", e)
+                }else{
+                    let server_message = e.data;
+                    console.log("server said: ", server_message)
+                    document.getElementById("socketOutPut").innerHTML= server_message;
+                }
+            }
+
+        </script>
+    </ol>
+    <p id="socketOutPut"></p>
+</div>
+
+<!--<script type="text/javascript">-->
+<!--    setTimeout(function(){-->
+<!--        location.reload();-->
+<!--    },1000)-->
+<!--</script>-->
+
+</body>
+

html/test/css/test.css

+p {
+    background-color:lightblue;
+    padding: 20px 5px;
+}
+
+h1 {
+    text-align: center;
+    text-decoration: overline;
+}
+
+div {
+    width: 300px;
+    margin: auto;
+    text-align: left;
+    background-color: yellow;
+}
+
+hr {
+    width: 100px;
+    border: 6px solid lightcoral;
+    border-radius: 5px;
+}

html/test/index.html

+<head>
+    <title>Demo static "Test" </title>
+    <link rel="stylesheet" type="text/css" href="css/test.css">
+</head>
+<h1> Test </h1>
+<h1> &#8595; </h1>
+
+<hr>
+<div class="center">
+    <p >
+        This is a static website located on /test  but virtually accessed by /spa1 and /spa2
+    </p>
+
+    <hr>
+
+    <ul>
+        <li>
+            <a href="css/test.css"> css/test.css </a>
+        </li>
+    </ul>
+    <h1> &#8595; </h1>
+    <ul>
+        <li>
+            <a href="/"> back to "/" &#x2192; "./html/" </a>
+        </li>
+    </ul>
+</div>
+
+
+

http_handler.go

+package main
+
+import (
+	"log"
+	"net/http"
+)
+
+type httpEntry func(http.ResponseWriter, *http.Request)
+
+var httpEntryMap = map[string]httpEntry{
+	apiV1Prefix:    apiV1Main,
+	apiV1WebSocket: apiV1WebSocketHandler,
+}
+
+func setupHTTPHandler() {
+
+	for key, val := range httpEntryMap {
+		http.HandleFunc(key, val)
+	}
+
+	log.Printf("Server started at %s:%s\n", config.Host, config.Port)
+	log.Fatal(http.ListenAndServe(config.Host+":"+config.Port, nil))
+	// log.Fatal(http.ListenAndServeTLS(config.Host+":"+config.Port, config.TlsCert, config.TlsKey, nil))
+}

main.go

+package main
+
+// [START import]
+import (
+	"log"
+	"net/http"
+)
+
+// [END import]
+// [START main_func]
+
+func main() {
+
+	err := config.readConfig() //
+	if err != nil {
+		log.Println(err)
+		log.Fatalf("unable to read %s, program quit\n", configFile)
+		return
+	}
+
+	// [START setting_port]
+	port := config.Port
+	if port == "" {
+		port = "8081"
+		log.Printf("Defaulting to port %s", port)
+	}
+	// [END setting_port]
+
+	setupRootFileServer()
+
+	//always last
+	setupHTTPHandler()
+}
+
+// [END main_func]
+
+func setupRootFileServer() {
+	//root of doc
+	for idx, node := range config.Static {
+		log.Printf("setting up static %d with %+v\n", idx, node)
+		fs := http.FileServer(http.Dir(node.Dir))
+		http.Handle(node.StaticUrl, http.StripPrefix(node.StripPrefix, fs))
+	}
+}