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Banking Demo — Money Transfers with Compensation

Event-sourced account management with two-phase transfers, saga-based compensation, and a full transaction audit trail.

Source Code: bases/orchestrix/banking_demo/

Quick Start

uv run python -m bases.orchestrix.banking_demo.main

What It Demonstrates

  • Event-sourced accounts — balance reconstructed from events
  • Transfer saga — two-phase debit/credit with automatic rollback
  • Compensation — if the credit leg fails, the debit is reversed
  • Account lifecycle — open, suspend, reactivate, close
  • Command handlers — BankingCommandHandlers wires everything together

Domain Model

Commands

Command Fields Description
OpenAccount account_id, owner_name, initial_balance Open a new account
DepositMoney account_id, amount, description Deposit funds
WithdrawMoney account_id, amount, description Withdraw funds
TransferMoney transfer_id, from_account_id, to_account_id, amount, description Transfer between accounts
SuspendAccount account_id, reason Suspend an account
ReactivateAccount account_id Reactivate a suspended account
CloseAccount account_id Close an account

Events

Event Description
AccountOpened Account created with initial balance
MoneyDeposited Funds added
MoneyWithdrawn Funds removed
AccountSuspended Account suspended
AccountReactivated Account reactivated
AccountClosed Account closed
TransferInitiated Transfer started by saga
TransferDebited Source account debited
TransferCompleted Transfer succeeded
TransferFailed Transfer failed after compensation
TransferReversed Compensation: debit reversed

Aggregate: Account

from orchestrix.core.eventsourcing.aggregate import AggregateRoot

@dataclass
class Account(AggregateRoot):
    owner_name: str = ""
    balance: Decimal = Decimal("0")
    status: AccountStatus = AccountStatus.ACTIVE   # ACTIVE | SUSPENDED | CLOSED
    transactions: list = field(default_factory=list)

Key methods: open(), deposit(), withdraw(), suspend(), reactivate(), close(). Business rules: no overdraft, no ops on suspended/closed accounts, no closing with non-zero balance.

Transfer Saga Flow

TransferMoney command
  ↓
TransferInitiated → TransferSaga
  ↓
WithdrawMoney (debit source)
  ↓
TransferDebited → TransferSaga
  ↓
DepositMoney (credit destination)
  ↓  success              ↓  failure
TransferCompleted ✅      DepositMoney (re-credit source)
                            ↓
                          TransferReversed → TransferFailed ❌

Code Structure

bases/orchestrix/banking_demo/
├── main.py       # Runnable entry point (async demo)
├── models.py     # Commands, Events, Enums
├── aggregate.py  # Account aggregate
├── handlers.py   # BankingCommandHandlers
├── saga.py       # TransferSaga
└── README.md

Usage Example

import asyncio
from decimal import Decimal
from orchestrix.core.eventsourcing.aggregate import AggregateRepository
from orchestrix.infrastructure.memory.store import InMemoryEventStore

from bases.orchestrix.banking_demo.aggregate import Account
from bases.orchestrix.banking_demo.models import OpenAccount, DepositMoney

async def main():
    store = InMemoryEventStore()
    repo = AggregateRepository(event_store=store)

    # Open account
    agg = Account()
    agg.open(OpenAccount(account_id="acc-1", owner_name="Alice", initial_balance=Decimal("1000")))
    repo.save(agg)

    # Deposit
    agg = repo.load(Account, "acc-1")
    agg.deposit(DepositMoney(account_id="acc-1", amount=Decimal("500"), description="Bonus"))
    repo.save(agg)

    print(f"Balance: {agg.balance}")  # 1500

asyncio.run(main())