定義：

遵循RFC6544協議的通信協議。Webcoket協議和http協議屬于并行關系，但是websocket是以http協議為基礎開發出來的（微軟用IhttpHandler接口中同時處理這兩種協議），同時他們都是以TCP協議為基礎。可以進行雙向通信、持久化通信。Http是單向通信協議、無狀態通信。

websocket協議（握手部分）：

GET /chat HTTP/1.1
Host: http://server.example.com
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Key: x3JJHMbDL1EzLkh9GBhXDw==
Sec-WebSocket-Protocol: chat, superchat
Sec-WebSocket-Version: 13
Origin:?http://example.com

比http握手多了幾個部分：

Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Key: x3JJHMbDL1EzLkh9GBhXDw==
Sec-WebSocket-Protocol: chat, superchat
Sec-WebSocket-Version: 13

這幾個部分告訴服務器，該請求是Webcoket，不是http了。

接收的數據

GET /chat HTTP/1.1
Host:?http://example.com:8000
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
Sec-WebSocket-Version: 13

發送的數據

HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=

?

服務端:

• 使用第三方的Fleck庫，建議采用吧，比較方便。
• 使用第三方的websocketsharp庫，不方便服務端主動推送數據到客戶端。
• 自己按照RFC6544協議，打包協議頭+socket API庫，收發數據。
• 使用IIS8.0以上可以處理websocket請求：

namespace SimpleWebSocketApplication { public class WebSocketHandler : IHttpHandler { public void ProcessRequest(HttpContext context) { //Checks if the query is WebSocket request. if (context.IsWebSocketRequest) { //If yes, we attach the asynchronous handler. context.AcceptWebSocketRequest(WebSocketRequestHandler); } } public bool IsReusable { get { return false; } } //Asynchronous request handler. public async Task WebSocketRequestHandler(AspNetWebSocketContext webSocketContext) { //Gets the current WebSocket object. WebSocket webSocket = webSocketContext.WebSocket; /*We define a certain constant which will represent size of received data. It is established by us and we can set any value. We know that in this case the size of the sent data is very small. */ const int maxMessageSize = 1024; //Buffer for received bits. var receivedDataBuffer = new ArraySegment<Byte>(new Byte[maxMessageSize]); var cancellationToken = new CancellationToken(); //Checks WebSocket state. while (webSocket.State == WebSocketState.Open) { //Reads data. WebSocketReceiveResult webSocketReceiveResult = await webSocket.ReceiveAsync(receivedDataBuffer, cancellationToken); //If input frame is cancelation frame, send close command. if (webSocketReceiveResult.MessageType == WebSocketMessageType.Close) { await webSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, String.Empty, cancellationToken); } else { byte[] payloadData = receivedDataBuffer.Array.Where(b => b != 0).ToArray(); //Because we know that is a string, we convert it. string receiveString = System.Text.Encoding.UTF8.GetString(payloadData, 0, payloadData.Length); //Converts string to byte array. var newString = String.Format("Hello, " + receiveString + " ! Time {0}", DateTime.Now.ToString()); Byte[] bytes = System.Text.Encoding.UTF8.GetBytes(newString); //Sends data back. await webSocket.SendAsync(new ArraySegment<byte>(bytes), WebSocketMessageType.Text, true, cancellationToken); } } } } }

• 使用TcpListener類庫，不能使用httpListener類庫，，創建監聽，并將發送的數據按RFC6544協議打包。

（創建監聽）
class Server {
public static void Main() {
TcpListener server = new TcpListener(IPAddress.Parse("127.0.0.1"), 80);

server.Start();
Console.WriteLine("Server has started on 127.0.0.1:80.{0}Waiting for a connection...", Environment.NewLine);

TcpClient client = server.AcceptTcpClient();

Console.WriteLine("A client connected.");
}
}
（接收數據）
TcpClient client = server.AcceptTcpClient();

Console.WriteLine("A client connected.");

NetworkStream stream = client.GetStream();

while(client.Available < 3)
{
// wait for enough bytes to be available
}
//enter to an infinite cycle to be able to handle every change in stream
while (true) {
while (!stream.DataAvailable);

Byte[] bytes = new Byte[client.Available];

stream.Read(bytes, 0, bytes.Length);
}
（打包發送的數據）
if (new System.Text.RegularExpressions.Regex("^GET").IsMatch(data))
{
const string eol = "\r\n"; // HTTP/1.1 defines the sequence CR LF as the end-of-line marker

Byte[] response = Encoding.UTF8.GetBytes("HTTP/1.1 101 Switching Protocols" + eol
+ "Connection: Upgrade" + eol
+ "Upgrade: websocket" + eol
+ "Sec-WebSocket-Accept: " + Convert.ToBase64String(
System.Security.Cryptography.SHA1.Create().ComputeHash(
Encoding.UTF8.GetBytes(
new System.Text.RegularExpressions.Regex("Sec-WebSocket-Key: (.*)").Match(data).Groups[1].Value.Trim() + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
)
)
) + eol
+ eol);

stream.Write(response, 0, response.Length);
}

客戶端：

• html5的JS庫
• Fleck庫
• websocketsharp庫
• 微軟自己的wensocketclient庫
• 自己按照RFC6544協議，打包協議頭+socket API庫，收發數據

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