To launch the service in production it requires adding or implementing following:
- add user authorization;
- implement DAO layer to persist data into some storage;
- extend service's API to minimal set of usual bank's account operations. For example to add following operations:
- account deposit;
- account withdraw;
- account operations history with search capability;
- lock/unlock account;
If we are developing the service as a part of more complex system with microservice approach I would proposed extract NotificationService into separate service that sends specific notifications triggered by coresponding events.