Yoon-ddo

Yoon-ddo

윤또의 개발공작실

Project1:Foreign Currency Asset Management System Development

3 minute read




Foreign Currency Asset Management System

Overview

A backend-focused financial platform for managing multi-currency assets, exchange rates, portfolio valuation, and AI-powered financial summaries.

This project focuses on:

  • High-volume financial transaction processing
  • Exchange-rate integration
  • Wallet ledger consistency
  • Portfolio valuation
  • Event-driven microservice architecture
  • Reliable settlement and transaction tracking

1. Core Features

1.1 Must-Have Features (MVP)

1) Multi-Currency Wallet Management

Manage balances for multiple foreign currencies per user.

Key Points

  • Single-user MVP design (multi-user architecture supported)
  • ISO currency codes (USD, JPY, EUR, etc.)

Features

  • Create currency wallets
  • Currency exchange
  • Balance inquiry
  • Deposit / withdrawal
  • Wallet balance updates
  • Transaction memo support
  • Balance validation
  • Insufficient balance prevention

Main Entities

  • Wallet
  • WalletTransaction

2) Exchange Rate API Integration (Korea Eximbank)

Integrates external exchange-rate APIs from Korea Eximbank.

Key Points

  • External API → Internal DTO conversion
  • Exchange-rate caching required

Features

  • Retrieve latest exchange rates
  • Store currency exchange rates
  • Exception handling for API failures
  • Snapshot fallback strategy

3) Portfolio Valuation (KRW / USD)

Convert and aggregate assets based on a selected base currency.

Key Points

  • Accurate financial calculations
  • Decimal precision handling

Features

  • Base currency selection (KRW / USD)
  • Total portfolio valuation
  • Per-currency converted values

1.2 Should-Have Features

1) Exchange Rate Snapshot History

Store historical exchange-rate snapshots.

Features

  • Daily exchange-rate snapshots
  • Historical exchange-rate lookup
  • Duplicate snapshot prevention

Main Entity

  • ExchangeRateSnapshot

2) Portfolio Profit & Loss (P/L)

Track valuation-based profit and loss.

Features

  • Portfolio valuation comparison
  • Currency-level P/L
  • Total portfolio P/L
  • Percentage change calculation

Notes

  • Unrealized valuation P/L only
  • No realized profit calculation

1.3 Could-Have Features

AI Summary Reports (LLM-based)

Generate AI-powered portfolio and exchange-rate summaries.

Input Data

  • 7-day / 14-day exchange-rate snapshots
  • Currency fluctuation rates
  • Portfolio allocation ratio

Features

  • Exchange-rate trend summaries
  • Market factor explanations
  • Portfolio impact analysis
  • Non-predictive financial commentary

Example

“USD/KRW increased by 1.8% over the last 7 days.”

2. Development Schedule

Project Timeline

Period Duration
2026-01-26 ~ 2026-02-23 4 Weeks

Weekly Goals

Week Goal
Week 1 Architecture & environment setup
Week 2 MVP implementation
Week 3 Exchange-rate history & P/L
Week 4 AI reporting & system refinement

3. Technology Stack

Backend

  • Java 17
  • Spring Boot
  • Spring Data JPA (Hibernate)
  • MySQL 8
  • Flyway

Validation & Documentation

  • Jakarta Validation
  • OpenAPI (Swagger)

Testing

  • JUnit5
  • Spring Boot Test

Infrastructure

  • Docker
  • Docker Compose
  • Kafka
  • Kubernetes

4. System Architecture

Architecture Goals

  • Event-driven microservice architecture
  • High scalability
  • Reliable transaction processing
  • Clear domain separation
  • Financial data consistency

Service Structure

services/
├── user-service
├── wallet-service
├── exchange-rate-service
├── valuation-service
└── report-service

Shared Libraries

libs/
├── common-web
├── common-event
└── common-kafka

Infrastructure

infra/
└── k8s/

Includes:

  • Kubernetes deployment manifests
  • HPA configuration
  • CronJobs
  • ConfigMap / Secret management

5. Database Design

users

Stores user account information.

Column Description
id User identifier
email Login email
name Display name
created_date Created timestamp
updated_date Updated timestamp

wallets

Stores currency wallet balances.

Column Description
user_id Owner user
currency_code ISO currency code
balance Current balance

wallet_events

Represents business-level wallet actions.

Examples:

  • Deposit
  • Withdrawal
  • Exchange

wallet_transactions

Ledger table for wallet balance changes.

Features

  • Tracks all financial balance changes
  • Supports auditing and validation
  • Stores post-transaction balance snapshots

exchange_rate_snapshots

Stores daily exchange-rate snapshot metadata.

exchange_rate_snapshot_details

Stores per-currency exchange-rate data.

ai_reports

Stores AI-generated financial summaries.

6. Transaction Ledger Design

Wallet Event Structure

wallet_events

Represents a single business action:

  • Deposit
  • Withdrawal
  • Exchange

wallet_transactions

Represents actual ledger entries.

Example

Action Transactions
Deposit 1 CREDIT
Withdrawal 1 DEBIT
Exchange 1 DEBIT + 1 CREDIT

7. Event-Driven Architecture

Kafka-based asynchronous communication between services.

Event Examples

WalletEventCreated
ExchangeRateSnapshotCreated

Benefits

  • Loose coupling
  • Scalability
  • Reliable event processing
  • Better service isolation

8. Reliability & Financial Consistency

Key Considerations

  • Idempotency handling
  • Transaction consistency
  • Exception handling
  • Ledger traceability
  • Financial precision
  • High-volume batch processing support

9. Future Improvements

  • Real-time exchange-rate streaming
  • Multi-user authentication
  • Distributed transaction handling
  • Redis caching
  • CI/CD pipeline
  • Observability & monitoring
  • Multi-region deployment

You May Also Enjoy