Let's assume we're trying to build a Proof of Concept type of banking system.
We have an Account entity in our system, those are presumably stored in some persistence layer.
However, for this task we don't care about that and how these accounts get into our app. Assume it's given.
What we want to achieve is to store these accounts in some data structure in the memory of our application.
We also got a service level interface com.devexperts.service.AccountService.getAccount
Going further you'll be presented several programming tasks. It's recommended to stick to suggested order.
Note:
Try to avoid changing signature of any method of AccountService as well as Account class.
However, you're free to introduce new methods and/or override existing ones.
Implement AccountService.clear, AccountService.createAccount and AccountService.getAccount
methods in most efficient way.
Let's assume one of your colleagues already implemented those methods and submitted the code for your review.
Goal: Perform code review and change implementation accordingly
Hint:
Consider performance of AccountService.getAccount method.
We want to start expanding our business logic, most important feature is to allow money transfers between accounts.
Goal:
Implement AccountService.transfer
Hint: Assume we're in a single-threaded environment
Given working and tested implementation of single-threaded AccountService.transfer provide
multi-threaded version
Goal: Have money transfer between accounts working in concurrent environment
Note: You can combine it with next task
Create a REST service for transfer method. It should still operate with accounts in-memory
Goal: Have money transfer between accounts accessible to the outside world
Details:
The operation is available at POST localhost:8080/api/operations/transfer with required query parameters:
source_id, target_id, amount.
Response codes are the following:
- 200 (OK) - successful transfer
- 400 (Bad Request) - one of the parameters in not present or amount is invalid
- 404 (Not Found) - account is not found
- 500 (Internal Server Error) - insufficient account balance
Hint: You can introduce new classes and dependencies
Create 2 tables for accounts and corresponding transfers. Accounts column set should correspond to java code. Same goes for transfers, however one additional column ('TRANSFER_TIME') representing datetime of transfer should be added. Insert there given test data. Provide SQL query that finds all accounts that in total transferred more than 1000$ starting from 2019-01-01
Hint: You can introduce new classes and dependencies