1. 스프링부트 웹 소켓 라이브러리 추가 // https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-websocket implementation group: 'org.springframework.boot', name: 'spring-boot-starter-websocket' 2. EchoHandler 작성 package com.reviewer.portfolio.controller; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import org.springframework.stereot..