Prerequisites

• JDK 11+ installed with JAVA_HOME configures
• Gradle configured

Supported technologies

Languages:

• Java

Framework/Module:

• Spring Boot
• Spring Framework
• Spring WebFlux - Reactive

Getting started

Problem Description

Requirement #1: Store a Purchase Transaction

The application must be able to accept and store (i.e., persist) a purchase transaction with a description, transaction date, and a purchase amount in United States dollars. When the transaction is stored, it will be assigned a unique identifier.

Field requirements

• Description: must not exceed 50 characters
• Transaction date: must be a valid date
• Purchase amount: must be a valid amount rounded to the nearest cent
• Unique identifier: must uniquely identify the purchase

Requirement #2: Retrieve a Purchase Transaction in a Specified Country’s Currency

Based upon purchase transactions previously submitted and stored, your application must provide a way to retrieve the stored purchase transactions converted to currencies supported by the Treasury Reporting Rates of Exchange API based upon the exchange rate active for the date of the purchase. https://fiscaldata.treasury.gov/datasets/treasury-reporting-rates-exchange/treasury-reporting-rates-of-exchange The retrieved purchase should include the identifier, the description, the transaction date, the original US dollar purchase amount, the exchange rate used, and the converted amount based upon the specified currency’s exchange rate for the date of the purchase.

Currency conversion requirements

• When converting between currencies, you do not need an exact date match, but must use a currency conversion rate less than or equal to the purchase date from within the last 6 months.
• If no currency conversion rate is available within 6 months equal to or before the purchase date, an error should be returned stating the purchase cannot be converted to the target currency.
• The converted purchase amount to the target currency should be rounded to two decimal places (i.e., cent).

Solution

Project Name : Payment Exchange

This is a simple gradle java spring boot application which exposes 2 RESTFul API endpoints

The Payment Exchange microservice is part of Internation Payments umbrella. The Payment Exchange microservice, is responsible for maintaining:

1. Create New Payments with Default USD currency
2. Retrieve an existing Payment in different country currency

Following are the 2 endpoints exposed by this microservice:

• POST /paymentexchange/api/v1/payments : Creates a new payment transaction in USD
• GET /paymentexchange/api/v1/payments/{transactionId}/{countryCurrencyDesc} : Retrieves an existing transaction in the sepecified Country Currency

Design Considerations

• A java based spring boot RESTful application which accepts HTTP requests in JSON format ONLY
• The program returns the custom result object which contains the output and errors(if any)
• The application uses in memory H2 database as the data store
• DB migration is being done using Flyway
• Payment Transaction Date has been deliberately kept an input to the request as its possible the payment might have been warehoused overnight
• The microservice loads all the country currency desc using the https://api.fiscaldata.treasury.gov/services/api/fiscal_service/v1/accounting/od/rates_of_exchange?fields=country_currency_desc&page%5Bsize%5D=500
• However, the above loading is disabled by default during the execution of tests
• The country currency is loaded in the memory to validate the user input to retrieve any existing transaction in specified country's currency

Validation

• The country currency description input for retrieving existing transaction should be part of the list exposed by Fiscal Treasury : https://api.fiscaldata.treasury.gov/services/api/fiscal_service/v1/accounting/od/rates_of_exchange?fields=country_currency_desc
• Please refer to the swagger for other mandatory fields and the format of the data

Build the spring boot application

./gradlew 

Generate Test Reports

./gradlew jacocoTestReport

Start the gradle Java application

./gradlew bootRun

Or

java -jar build/libs/paymentsexchange-0.0.1-SNAPSHOT.jar

Swagger

Swagger can be found in the below url:

http://localhost:8080/paymentexchange/swagger-ui.html

Postman Collection

Postman collection is also included in the archive, named as Ledger Growth.postman_collection.json

Create New Payment Transaction

curl --location --request POST 'http://localhost:8080/paymentexchange/api/v1/payments' \
--header 'Content-Type: application/json' \
--data-raw '{
    "purchaseAmount": 12345.22,
    "transactionDescription": "sample payment",
    "transactionDate": "2023-09-05T20:01:18"
}'

• Response

{
  "originalCurrency": "USD",
  "transactionId": "dd939d41-7860-42c3-8b61-c6156c88762a",
  "purchaseAmount": 12345.22,
  "transactionDescription": "sample payment",
  "transactionDate": "2023-09-05T20:01:18",
  "createdUser": "System"
}

Retrieve Existing Payment in India Rupee

curl --location --request GET 'http://localhost:8080/paymentexchange/api/v1/payments/dd939d41-7860-42c3-8b61-c6156c88762a/India-Rupee' \
--header 'Content-Type: application/json' 

• Response

{
    "paymentTransactionDetails": {
        "originalCurrency": "USD",
        "transactionId": "dd939d41-7860-42c3-8b61-c6156c88762a",
        "purchaseAmount": 12345.22,
        "transactionDescription": "some",
        "transactionDate": "2023-09-05T20:01:18",
        "createdUser": "System"
    },
    "exchangeRateDetails": {
        "exchangeRate": 82.09,
        "originalPurchaseAmount": 12345.22,
        "convertedPurchaseAmount": 1013419.11,
        "convertedCountryCurrency": "India-Rupee"
    }
}