javascript之ProtoBuf在websocket中的使用

因为ProtoBuf的序列化效率和大小都非常好，所以它在网络通信上面应用越来越多；而webosocket也随着web3.0应用越来越广泛，而将这两个结合在一起的也会慢慢形成一种趋势；本人是为了测试自已写的一个C# websocket，所以在web上面结合pb也写了一个js实例:

1.首先下载protobuf.js

2.引入protobuf相关js文件

3.创建proto文件

1 package wenlipackage;
2 syntax = "proto3";
3 
4 message WSMessage {  
5     required string id = 1;
6     required string content = 2;
7     required string sender = 3;
8     required string time = 4;
9 }

js的protobuf格式类型有

Field type	Expected JS type (create, encode)	Conversion (fromObject)
s-/u-/int32 s-/fixed32	`number` (32 bit integer)	`value \| 0` if signed `value >>> 0` if unsigned
s-/u-/int64 s-/fixed64	`Long`-like (optimal) `number` (53 bit integer)	`Long.fromValue(value)` with long.js `parseInt(value, 10)` otherwise
float double	`number`	`Number(value)`
bool	`boolean`	`Boolean(value)`
string	`string`	`String(value)`
bytes	`Uint8Array` (optimal) `Buffer` (optimal under node) `Array.<number>` (8 bit integers)	`base64.decode(value)` if a `string` `Object` with non-zero `.length` is assumed to be buffer-like
enum	`number` (32 bit integer)	Looks up the numeric id if a `string`
message	Valid message	`Message.fromObject(value)`

4.初始化protobuf，对相关数据进行序列化和反序列化

 1 <script type="text/javascript">
 2         var WSMessage;
 3         var wsmessage;
 4         var buffer;
 5         protobuf.load("/proto/Message.proto", function (err, root) {
 6             if (err) throw err;
 7             WSMessage = root.lookup("wenlipackage.WSMessage");
 8             wsmessage = WSMessage.create({ id: "1", content: "hello", sender: "web", time: new Date().getTime() });
 9             buffer = WSMessage.encode(wsmessage).finish();
10         });
11 </script>

WSMessage是一个解码编码器

wsmessage是具体的某个定义的proto实例

buffer是一个8位无符号的字节数组

5.连接到websocket并发送序列化的消息和接收反序列化的消息

 1 <script type="text/javascript">
 2         var wsUri = "ws://127.0.0.1:8082/";
 3         var output;
 4         function init() {
 5             output = document.getElementById("output");
 6             testWebSocket();
 7         }
 8         function testWebSocket() {
 9             websocket = new WebSocket(wsUri);
10             websocket.onopen = function (evt) {
11                 onOpen(evt)
12             };
13             websocket.onclose = function (evt) {
14                 onClose(evt)
15             };
16             websocket.onmessage = function (evt) {
17                 onMessage(evt)
18             };
19             websocket.onerror = function (evt) {
20                 onError(evt)
21             };
22         }
23         function onOpen(evt) {
24             writeToScreen("CONNECTED");
25             doSend(buffer);
26         }
27         function onClose(evt) {
28             writeToScreen("DISCONNECTED");
29         }
30         function onMessage(evt) {
31             var reader = new FileReader();
32             reader.readAsArrayBuffer(evt.data);
33             reader.onload = function (e) {
34                 var buf = new Uint8Array(reader.result);
35                 writeToScreen('<span style="color: blue;">RESPONSE: ' + WSMessage.decode(buf).content + '</span>');
36             }
37         }
38         function onError(evt) {
39             writeToScreen('<span style="color: red;">ERROR:</span> ' + evt.data);
40         }
41         function doSend(message) {
42             writeToScreen("SENT: " + wsmessage.content);
43             websocket.send(buffer);
44         }
45         function writeToScreen(message) {
46             var pre = document.createElement("p");
47             pre.style.wordWrap = "break-word";
48             pre.innerHTML = message;
49             output.appendChild(pre);
50         }
51         window.addEventListener("load", init, false);
52 </script>

上面因为我的websocket server 返回一是二进制，所以浏览器接收到的是一个blob，这里注意对blob的处理

6.互通测试