[카프카활용] 챕터 5. CSS 모듈

1. CB사 모듈 개발 연동

CssApplication

이것도 웹 서버가 떠서, 요청 오는 다양한 API를 처리해 줄 수 있어야 한다.

package happyprogfrog.css

import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.runApplication

@SpringBootApplication
class CssApplication

fun main(args: Array<String>) {
    runApplication<CssApplication>(*args)
}

 

build.gradle.kts

plugins {}

version = "0.0.1"

dependencies {
    implementation("org.springframework.boot:spring-boot-starter-web")
}

 

포트 변경

api, consumer랑 겹치치 않도록 지정 한다.

server:
  port: 8081

 

LoanRequestDto

대출 심사에 필요한 정보를 담는 Dto

package happyprogfrog.css.dto

class LoanRequestDto {
    data class RequestInputDto(
        val userKey: String,
        val userName: String,
        val userIncomeAmount: Long,
        var userRegistrationNumber: String
    )
}

 

 

LoanResultDto

대출 심사 결과를 담는 Dto

package happyprogfrog.css.dto

class LoanResultDto {
    data class ResponseDto(
        val userKey: String,
        val interest: Double,
        val limitAmount: Long
    )
}

 

LoanReviewService

대출 심사 로직이 들어간 Service

package happyprogfrog.css.service

import happyprogfrog.css.dto.LoanRequestDto
import happyprogfrog.css.dto.LoanResultDto
import org.springframework.stereotype.Service

@Service
class LoanReviewService {
    fun loanReview(loanRequestDto: LoanRequestDto.RequestInputDto): LoanResultDto.ResponseDto {
        // 리턴값을 주기 위한 예시이며, 실제로 CB 사의 로직은 이렇게 단순하지 않음
        if (loanRequestDto.userIncomeAmount < 0) throw RuntimeException("Invalid userIncomeAmount Param")
        if (loanRequestDto.userIncomeAmount < 10000000) return LoanResultDto.ResponseDto(loanRequestDto.userKey,0.0, 100000000)
        if (loanRequestDto.userIncomeAmount < 20000000) return LoanResultDto.ResponseDto(loanRequestDto.userKey,10.0, 200000000)
        if (loanRequestDto.userIncomeAmount < 30000000) return LoanResultDto.ResponseDto(loanRequestDto.userKey,9.0, 300000000)
        if (loanRequestDto.userIncomeAmount < 40000000) return LoanResultDto.ResponseDto(loanRequestDto.userKey,8.0, 400000000)
        if (loanRequestDto.userIncomeAmount < 50000000) return LoanResultDto.ResponseDto(loanRequestDto.userKey,7.0, 500000000)
        if (loanRequestDto.userIncomeAmount >= 50000000) return LoanResultDto.ResponseDto(loanRequestDto.userKey,6.0, 600000000)
        throw RuntimeException("Invalid userIncomeAmount Param")
    }
}

 

LoanRequestController

• consumer로 부터 오는 요청을 받는 Controller
• 요청을 service로 보내 응답을 받아 리턴

package happyprogfrog.css.controller

import happyprogfrog.css.dto.LoanRequestDto
import happyprogfrog.css.dto.LoanResultDto
import happyprogfrog.css.service.LoanReviewService
import org.springframework.web.bind.annotation.PostMapping
import org.springframework.web.bind.annotation.RequestBody
import org.springframework.web.bind.annotation.RequestMapping
import org.springframework.web.bind.annotation.RestController

@RestController
@RequestMapping("/css/api/v1")
class LoanRequestController(
    private val loanReviewService: LoanReviewService
) {
    @PostMapping("/request")
    fun loanReview(@RequestBody requestInputDto: LoanRequestDto.RequestInputDto
    ): LoanResultDto.ResponseDto =
        loanReviewService.loanReview(requestInputDto)
}

 

2. Consumer 모듈에서 CB사 모듈 호출하고 결과를 DB에 저장하기

ReviewResponseDto

• CB사의 응답을 담은 Dto
• LoanReview 엔티티로 변환해서 DB에 저장하는 데 사용함

package happyprogfrog.consumer.dto

import happyprogfrog.domain.domain.LoanReview

data class ReviewResponseDto(
    val userKey: String,
    val interest: Double,
    val limitAmount: Long
) {
    fun toLoanReviewEntity(): LoanReview =
        LoanReview(
            userKey = userKey,
            loanInterest = interest,
            loanLimitedAmount = limitAmount
        )
}

 

LoanRequestService

• CB사로 요청 보내고 응답 저장하는 로직 수행

package happyprogfrog.consumer.service

import happyprogfrog.consumer.dto.ReviewResponseDto
import happyprogfrog.domain.domain.LoanReview
import happyprogfrog.domain.repository.LoanReviewRepository
import happyprogfrog.kafka.dto.LoanRequestDto
import org.springframework.boot.web.client.RestTemplateBuilder
import org.springframework.stereotype.Service
import java.time.Duration

@Service
class LoanRequestService(
    private val loanReviewRepository: LoanReviewRepository
) {
    companion object {
        const val CSS_URL = "http://localhost:8081/css/api/v1/request"
    }

    fun loanRequest(loanRequestDto: LoanRequestDto) {
        // CB 사에 요청 보내기
        val reviewResult = loanRequestToCb(loanRequestDto)

        // 응답값을 DB에 저장하기
        saveLoanReviewData(reviewResult.toLoanReviewEntity())
    }

    private fun loanRequestToCb(loanRequestDto: LoanRequestDto): ReviewResponseDto {
        // WebClient 를 사용하는 방법도 있음
        val restTemplate = RestTemplateBuilder()
            .setConnectTimeout(Duration.ofMillis(1000))
            .setReadTimeout(Duration.ofMillis(1000))
            .build()

        return restTemplate.postForEntity(CSS_URL, loanRequestDto, ReviewResponseDto::class.java).body!!
    }

    private fun saveLoanReviewData(loanReview: LoanReview) = loanReviewRepository.save(loanReview)
}

 

LoanRequestConsumer

• 특정 토픽을 Listen하고 있다가, 메시지가 발행되면 이를 consume해서 service 로직을 태움

package happyprogfrog.consumer.kafka

import com.fasterxml.jackson.databind.ObjectMapper
import happyprogfrog.consumer.service.LoanRequestService
import happyprogfrog.kafka.dto.LoanRequestDto
import org.springframework.kafka.annotation.KafkaListener
import org.springframework.stereotype.Service

@Service
class LoanRequestConsumer(
    private val objectMapper: ObjectMapper,
    private val loanRequestService: LoanRequestService
) {
    @KafkaListener(topics = ["loan_request"], groupId = "fintech")
    fun loanRequestTopicConsumer(message: String) {
        val loanRequestKafkaDto = objectMapper.readValue(message, LoanRequestDto::class.java)
        loanRequestService.loanRequest(loanRequestKafkaDto)
    }
}

 

3. 실행

• api, consumer, css 웹 서버를 띄우고 대출 심사 요청 API 호출
• 대출 심사 결과가 DB에 잘 저장되는지
• 대출 심사 결과 확인 API 호출 시 응답이 잘 오는지 확인