DDD Approach to Access External Information

Question

I have an existing bank application classes as shown below. The banks account can be of SavingsBankAccount or FixedBankAccount. There is an operation called IssueLumpSumInte

Answer 1

Things that strike me as weird:

• Your IBankAccount has a method FreezeAccount, but I presume that all accounts would have quite similar behavior? Perhaps a BankAccount class is warranted that implements some of the interface?
• AccountStatus should probably be an enum? What should happen if an account is "Forzen"?