Describe a procedure using data structure and standard functions

chatSession.go

 		}
 	}
 }
+
+//OneMessage  a description of what to send /receive
+type OneMessage struct {
+	Type       string  `json:"Type"` //MessageType
+	Text       string  `json:"Text"` //for text messages
+	Pic        MediaID `json:"Pic"`
+	Voice      MediaID `json:"Voice"`
+	ShortVideo MediaID `json:"ShortVideo"`
+	Video      MediaID `json:"Video"`
+}
+
+type initProcFunc func(openid string) (newstate chatState)
+type sendProcMsgFunc func(openid string) (newstate chatState)
+type recvProcMsgFunc func(openid string, msg OneMessage) (newstate chatState)
+type cleanProcFunc func(openid string) (newstate chatState)
+
+//Procedure  a description about all procedure
+type Procedure struct {
+	init  initProcFunc    //init function
+	send  sendProcMsgFunc //function for sending customized message
+	recv  recvProcMsgFunc //function for receiving message, possibly transfer to new state
+	clean cleanProcFunc   //function for cleanning up
+}