Banking Service REST API

Development assignment for Backend Developer at Finologee

See Finologee - Java Development Assignment - Luxembourg.pdf for assignment instructions.

What has been implemented

• All the main requirements
• Payment execution as a single transaction
• Swagger specification for the REST API
• Docker build

The application runs on Java 20 using Spring Boot 3.0.6. An H2 database is populated on startup. The initial data is described below.

What has not been implemented

• Pagination for payments
• Registering of fraud tentatives
• Final execution of payments (mark payment as executed and update end-of-day balances)

How to run the application

The application runs on Java 20, so a JDK should be installed on the build system.

Manually

Using Maven, you can run the following command:

./mvnw install

This will put an executable JAR in ./target, which can be run using:

java -jar target/*.jar

Using Docker

Build the JAR file as before and then execute the following command to extract the layers from the JAR:

mkdir target/extracted && java -Djarmode=layertools -jar target/*.jar extract --destination target/extracted

Building the image:

docker build -t bankingservice .

Run it using the following command:

docker run -p 8080:8080 bankingservice

Application summary

Using a tool like Postman (see resources folder for a sample collection), a user can send requests to the REST API.

First the user has to log in using the POST /login endpoint providing username and password as basic authentication.

Then the now authenticated user can execute payments, view his/her payments, delete a payment or list his/her bank accounts. The user can also update the user details (address, password) using the dedicated endpoint.

To create a payment, the following constraints apply:

• The giver bank account has to be owned by the user
• Payments to the same account as the giver are not valid
• Payments only be executed if the account balance is sufficient
• Payments to the following list of accounts are forbidden:
  • LU280019400644750000
  • LU120010001234567891
• The IBAN of the beneficiary is validated with https://openiban.com/validate

The account balances will be updated, if they belong to this banking service.

The payment is processed in a single transaction, creating the payment in the database and updating the available balances.

When the user has finished, he can log out using the POST /logout endpoint, which will invalidate the session.

Endpoints

• POST /login: The user can log in using basic authentication
• POST /logout: The user can log out
• PUT /update-user: Update the user details and password
• POST /payment: Create a new payment
• GET /accounts: List the user's bank accounts
• GET /payments: List the created payments for the authenticated user
• DELETE /payment: Delete a payment using its ID. Only payments that have not yet been executed can be deleted.

For a detailed overview of the API, visit the Swagger documentation at http://localhost:8080/swagger-ui.html

Populated data

Users

ID	User	Password	Accounts
1	user1	user1Password	1,2
2	user2	user2Password	2,3,4,9,19
3	user3	user3Password	2,8,13,16
4	user4	user4Password	8,14
5	user5	user5Password	4,12,13,16
6	user6	user6Password	10,15,18
7	user7	user7Password	5,6,17
8	user8	user8Password	7,11,13,20

Accounts

ID	Account name	IBAN	Balance	Users
1	Personal	LU584022594948990503	578.98	1
2	Work	LU907047173626189281	4135.14	1,2,3
3	Checking	LU337685598868536287	21545.32	2
4	Joint	LU840552586110383855	201.00	2,5
5	Primary	LU068976849336652168	984512.23	7
6	Secondary	LU148716017016374383	382690.16	7
7	Joy	LU798574254737992988	232663.94	8
8	Holidays	LU881912185721376358	421234.41	3,4
9	Personal	LU191013601444141763	158052.05	2
10	Savings	LU710564368935005652	292888.94	6
11	Personal	LU222549371173567471	168211.44	8
12	Savings	LU261309808416076323	223757.44	5
13	Work	LU654310230678616664	207268.46	3,5,8
14	Expenses	LU231866912041681639	326704.48	4
15	Personal	LU429127592687822778	98377.59	6
16	Joint account	LU786522695111559649	23818.53	3,5
17	Savings	LU259786109895524005	252442.60	7
18	Pension	LU744005943189772712	412747.20	6
19	Savings	LU130189044953642517	359691.69	2
20	Trading	LU081651725326393823	278739.76	8