메세지 인터페이스 추가

 import React, { useContext, useState } from 'react';
 import { RouteComponentProps } from 'react-router';
 import { Footer } from './Footer';
+import { MessageResponse } from './Message';
 import SocketContext from './SocketContext';
 
 export const Login: React.FC<RouteComponentProps> = ({ history }) => {
@@ -8,8 +9,8 @@ export const Login: React.FC<RouteComponentProps> = ({ history }) => {
     const [ username, setUsername ] = useState("");
 
     const login = () => {
-      socket.emit('login', username, ({ ok } : { ok: boolean }) => {
-        if (ok) {
+      socket.emit('login', username, (response : MessageResponse<null>) => {
+        if (response.ok) {
           history.push('/rooms');
         } else {
           console.error('login error!'); // TODO: 팝업 에러?

+export interface MessageResponse<T> {
+  ok: boolean;
+  reason?: string;
+  result?: T;
+}
+
+export class MessageType {
+  static readonly LOGIN = "login";
+  static readonly ROOM_LIST_REQUEST = "room_list_request";
+  static readonly ROOM_JOIN = "room_join";
+  static readonly ROOM_LEAVE = "room_leave";
+  static readonly ROOM_USER_UPDATE = "room_user_update";
+  static readonly ROOM_CHAT = "room_chat";
+}