##### OpenIM五种系统消息类型
* TextMessage（Ping/Pone Message）
* BinaryMessage（Chat Message)
* CloseMessage（客户端关闭连接）
* PingMessage
* PongMessage
##### BinaryMessage（Req/Resp）
```golang
type Req struct {  
    ReqIdentifier int32  `json:"reqIdentifier" validate:"required"`  
    Token         string `json:"token"`  
    SendID        string `json:"sendID"        validate:"required"`  
    OperationID   string `json:"operationID"   validate:"required"`  
    MsgIncr       string `json:"msgIncr"       validate:"required"`  
    Data          []byte `json:"data"`  
}
type Resp struct {  
    ReqIdentifier int32  `json:"reqIdentifier"`  
    MsgIncr       string `json:"msgIncr"`  
    OperationID   string `json:"operationID"`  
    ErrCode       int    `json:"errCode"`  
    ErrMsg        string `json:"errMsg"`  
    Data          []byte `json:"data"`  
}
```

##### ReqIdentifier
```golang
WSGetNewestSeq        = 1001  
WSPullMsgBySeqList    = 1002  
WSSendMsg             = 1003  // 一般聊天消息
WSSendSignalMsg       = 1004  
WSPullMsg             = 1005  
WSGetConvMaxReadSeq   = 1006  
WsPullConvLastMessage = 1007  
WSPushMsg             = 2001  
WSKickOnlineMsg       = 2002  
WsLogoutMsg           = 2003  
WsSetBackgroundStatus = 2004  
WsSubUserOnlineStatus = 2005  
WSDataError           = 3001
```