에러부분이 나서 진행이 안되네요... 의존성 문제인거 같기도한데

Did you create a class or interface for MemberRepository?

안녕하세요

It seems return type of the method findByid(Long id) should be Optional(Member).

직접 만든 라이브러리의 경우 어떻게 배포 되는건가요?

We normally never include any built files - jar, war - in the source code repository like GitHub. Instead, we have a separate repository (e.g. Nexus) where the jar file is uploaded, so projects can just declare the dependency (e.g. pom.xml for maven) to download it.

MemberService에 @Transactional 붙이는 이유

Though it is just a guess, in the pure jdbc example you might explicitly open/close transaction in the code. On JPA, same functionality is controlled by the Transactional annotation.

안녕하세요

API can be used by any agent - web, mobile or other systems. Reason it uses restApi is to simply return data only, as opposed to normal controller returns html element.