Feature/52 add websocket handler and its service interface

[Doyuni]

I added websocket handler first. I will add service interface later.

Websocket Process

1. Open Handshake : It occurs in DssHttpRequestHandler.java

   • Client's handshake request : HTTP Upgrade Request using only GET method

     GET /chat HTTP/1.1
     Host: dssserver.example.com
     Upgrade: websocket
     Connection: Upgrade
     Sec-WebSocket-Key: ScmyStFFNlK9TVHteROMKA==
     Origin: http://example.com
     Sec-WebSocket-Version: 13

   • Server's handshake response : Accept websocket connection with value combined websocket-key & GUID

     HTTP/1.1 101 Switching Protocols
     upgrade: websocket
     connection: upgrade
     sec-websocket-accept: t3gjBK9ILNyvtnyC+vneMlV98g4=

2. Sending and Receiving Data Frame (Current: Echo message) : It occurs in DssWebSocketHandler.java

   • If client sends message to dss server, dss server receives message called Websocket Frame.

3. Close connection

   I tested it works fine using Jetty websocket client or Echo Test ([https://www.websocket.org/echo.html])(https://www.websocket.org/echo.html).

Here is test logs.

[INFO ] [DssWebSocketServer.java]start(66) : Server Started
[INFO ] [DssWebSocketChannelInitializer.java]initChannel(20) : Try to initChannel
[INFO ] [DssHttpRequestHandler.java]handleHttpRequest(47) : Request URI: /websocket
[INFO ] [DssHttpRequestHandler.java]handleHttpRequest(65) : Request WebSocket Protocol
[INFO ] [DssHttpRequestHandler.java]handleHandshake(95) : Handshake Start
[INFO ] [DssHttpRequestHandler.java]handleHandshake(98) : ws://localhost:8181/websocket
[INFO ] [DssHttpRequestHandler.java]handleHandshake(106) : Handshake Success
[INFO ] [DssWebSocketHandler.java]channelRead(17) : Client Channel : [id: 0x70e76c8c, L:/127.0.0.1:8181 - R:/127.0.0.1:55702]
[INFO ] [DssWebSocketHandler.java]channelRead(23) : TextWebSocketFrame Received
[INFO ] [DssWebSocketHandler.java]channelRead(28) : Received Message : Hello! Dss Server
[INFO ] [DssWebSocketHandler.java]channelRead(17) : Client Channel : [id: 0x70e76c8c, L:/127.0.0.1:8181 - R:/127.0.0.1:55702]
[INFO ] [DssWebSocketHandler.java]channelRead(36) : CloseWebSocketFrame Received
[INFO ] [DssWebSocketHandler.java]channelRead(39) : ReasonText : 
[INFO ] [DssWebSocketHandler.java]channelRead(40) : StatusCode : 1000
[INFO ] [DssWebSocketChannelInitializer.java]initChannel(20) : Try to initChannel
[INFO ] [DssHttpRequestHandler.java]handleHttpRequest(47) : Request URI: /websocket?encoding=text
[INFO ] [DssHttpRequestHandler.java]handleHttpRequest(65) : Request WebSocket Protocol
[INFO ] [DssHttpRequestHandler.java]handleHandshake(95) : Handshake Start
[INFO ] [DssHttpRequestHandler.java]handleHandshake(98) : ws://127.0.0.1:8181/websocket
[INFO ] [DssHttpRequestHandler.java]handleHandshake(106) : Handshake Success
[INFO ] [DssWebSocketHandler.java]channelRead(17) : Client Channel : [id: 0xfed0f797, L:/127.0.0.1:8181 - R:/127.0.0.1:55731]
[INFO ] [DssWebSocketHandler.java]channelRead(23) : TextWebSocketFrame Received
[INFO ] [DssWebSocketHandler.java]channelRead(28) : Received Message : Hello

Code Review

• I want to add WebSocketServerProtocolHandler but It can not handle http message in Echo Test ([https://www.websocket.org/echo.html]).
  Because this handler replaces HttpServerCodec into WebSocketFrameCodec.
  If I use this handler, I don't need to write handshake method.

• I want to handle websocket endpoint well.
  ex) URI: "/websocket" or "/websocket?encoding=text" or "/websocket/example"
  These endpoints all mean "request websocket"?

Thank you for reading.