Overview

The Ledger Service is the authoritative source for all financial data. It maintains the general ledger using double-entry bookkeeping principles and ensures that all financial transactions are properly recorded and balanced.

Key Responsibilities

Journal Entry Management

• Record all financial transactions as journal entries
• Validate double-entry bookkeeping rules (debits = credits)
• Generate automated entries from business events
• Support manual journal entries with approval workflow

Account Management

• Maintain chart of accounts
• Track account balances in real-time
• Support multiple currencies
• Historical balance tracking

Financial Integrity

• Ensure ACID compliance for all transactions
• Validate business rules before posting
• Prevent duplicate entries (idempotency)
• Audit trail for all changes

Chart of Accounts Structure

Assets (1000-1999)

• 1010: Cash and Cash Equivalents
• 1020: Accounts Receivable
• 1030: Inventory
• 1100: Fixed Assets

Liabilities (2000-2999)

• 2010: Accounts Payable
• 2020: Accrued Expenses
• 2100: Long-term Debt

Equity (3000-3999)

• 3010: Common Stock
• 3020: Retained Earnings

Revenue (4000-4999)

• 4010: Sales Revenue
• 4020: Service Revenue

Expenses (5000-5999)

• 5010: Cost of Goods Sold
• 5020: Operating Expenses
• 5030: Payment Processing Fees

Technical Details

Technology Stack:

• Runtime: Java 17
• Framework: Spring Boot
• Database: PostgreSQL with ACID guarantees
• Event Store: For audit trail
• Reporting: PostgreSQL read replicas

Data Model:

• Event-sourced for complete audit trail
• Materialized views for current balances
• Partitioned by fiscal period for performance

Performance:

• Transaction Processing: < 100ms
• Balance Queries: < 50ms
• Supports 10,000+ transactions per day

Integration Points

• Payment Processing Service: Receives payment events
• Invoice Service: Receives invoice events
• Reconciliation Service: Provides data for reconciliation
• Reporting Service: Feeds financial reports