README.md

playground-chat-server

Intro & Motivation

This service is simple chatting server using websocket protocol. The reason why I develop this service is to learn websocket concept.

Tech

Server

Kotlin, Spring(MVC, Websocket, Redis, Security, Freemarker), JJWT ..

Front

Vue

If you want to know more information about my project's tech referencing gradle file

Architecture

Feature

HTTP

• /chat/rooms : Get all chat-room information
• /chat/room/{roomId} : Get specified chat-room information
• /chat/room?name="chatRoomName : create new chat-room
• /chat/user : get current user info

STOMP(Websocket)

• /ws-stomp : connect stomp
• /sub/chat/room/{roomId} : subscribe roomId topic
• /pub/chat/message : publish message to specific topic (message include topic information)

Get Start (local environment)

# clone project and move to project folder
git clone https://github.com/hyuk0309/playground-chat-server.git
cd ./playground-chat-server/

# build and execute project
./gradlew clean build
cd ./build.libs
java -jar playground-chat-server-0.0.1-SNAPSHOT.jar

What I Learn

Learned Concept

• WebSocket Protocol & Spring Support

  • ref : https://docs.spring.io/spring-framework/docs/4.3.x/spring-framework-reference/html/websocket.html#:~:text=26-,.%C2%A0WebSocket%20Support,-This%20part%20of
  • my blog : https://hyuk0309.tistory.com/19

• STOMP & Spring Support

  • ref : https://docs.spring.io/spring-framework/docs/4.3.x/spring-framework-reference/html/websocket.html#:~:text=26.4-,STOMP,-The%20WebSocket%20protocol
  • my blog : https://hyuk0309.tistory.com/20

• spring data redis pub sub

  • ref
    • redis docs : https://redis.io/docs/manual/pubsub/
    • spring docs : https://spring.io/guides/gs/messaging-redis/
    • blog : https://www.baeldung.com/spring-data-redis-pub-sub
    • blog : https://brunch.co.kr/@springboot/374
  • my blog : https://hyuk0309.tistory.com/21

• @Resource principle

  • code

  @Repository
  class ChatRoomRepository {
  
    @Resource(name = "redisTemplate")
    private lateinit var hashOpsChatRoom: HashOperations<String, String, ChatRoom>
  
    @Resource(name = "redisTemplate")
    private lateinit var hashOpsEnterInfo: HashOperations<String, String, String>
  
    @Resource(name = "redisTemplate")
    private lateinit var valueOps: ValueOperations<String, String>
    ...
  }

  • Question? : How Spring Inject Dependency when name bean and target bean are different.
    • Answer : there is converter helping that task.
      • ref
        • logic start : org.springframework.beans.factory.support.AbstractBeanFactory.adaptBeanInstance
        • key class : org.springframework.data.redis.core.HashOperationsEditor

Issue

• FreeMarkerViewReolver's default suffix
  • Reason : dafult suffix : .htlh
    • ref : spring-projects/spring-boot#15131
  • Solution : change ftl extension to ftlh
• Can't find Webjar Dependency
  • Solution : add Resource Handler
    • ref : https://www.baeldung.com/maven-webjars
• SLF4J multi binding Issue
  • Reason : SLF4J will bind with one logging framework at a time. but my classpath have two binder(provider)
    • ref : https://www.baeldung.com/slf4j-classpath-multiple-bindings
  • Solution : exclude one logging framework using gradle.
    • ref :
      • Listing dependency tree : https://docs.gradle.org/7.3/userguide/viewing_debugging_dependencies.html#sec:listing_dependencies
      • exclude specific module : https://docs.gradle.org/current/userguide/dependency_downgrade_and_exclude.html#sec:excluding-transitive-deps
        • how to know group and module name : https://stackoverflow.com/questions/43582247/how-to-know-if-duplicate-library-is-module-or-group
• Spring Securit's WebSecurityConfigurerAdapter was deprecated
  • ref : https://spring.io/blog/2022/02/21/spring-security-without-the-websecurityconfigureradapter
• JJWT(jsonwebtoken) deprecated api
  • Reason : confused api
  • ref : https://stackoverflow.com/questions/40252903/static-secret-as-byte-key-or-string/40274325#40274325
• The difference between the Spring Container in an operational environment and the Spring Container in a testing environment
  • reason : When testing, If we use WebEnvironment.MOCK, than SpringBootContextLoader load GenericWebApplicationContext. But, If we use WebEnvironment.RANDOM_PORT or WebEnvironment.DEFINED_PORT, than load AnnotationConfigServletWebServerApplicationContext.

Reference

• Example Code

  • Blog : https://www.daddyprogrammer.org/post/4077/spring-websocket-chatting/
  • Bolg : https://velog.io/@dvmflstm/Spring-Webflux-Kotlin-Coroutine-Actor%EB%A5%BC-%EC%9D%B4%EC%9A%A9%ED%95%9C-Websocket-Server-%EB%A7%8C%EB%93%A4%EA%B8%B0

• Official Docs

  • Spring Docs : https://docs.spring.io/spring-framework/docs/4.3.x/spring-framework-reference/html/websocket.html