build.gradle 에서 dependencies websocket 추가- implementation 'org.springframework.boot:spring-boot-starter-websocket' build.gradle 원본 소스(버젼마다 호환성의 문제로 전체 source) plugins { id 'org.springframework.boot' version '2.6.1' id 'io.spring.dependency-management' version '1.0.11.RELEASE' id 'java' } group = 'com.coforward' version = '0.0.1-SNAPSHOT' sourceCompatibility = '1.8' configurations { compileOnly {..