http://sungbine.github.io/tech/post/2015/02/15/tomcat%EA%B3%BC%20apache%EC%9D%98%20%EC%97%B0%EB%8F%99.html
https://velog.io/@tjswlsdl135/Web-Server%EC%95%84%ED%8C%8C%EC%B9%98-vs-WAS%ED%86%B0%EC%BA%A3
https://www.lifencoding.com/web/28?p=1
https://oingdaddy.tistory.com/344
