Parser Digital Coding Challenge

By Gary Murray

Scope of the work

Create a Java REST application for a financial institution that contains the information and operations for Accounts​ and ​Transfers.​

This application should have the following ​persisted information​ for each entity type. You may decide the persistence system:

Account
accountId	Account​ Identifier
iban	Account I​BAN (2 chars + 22 digits)
balance	Account​ balance
currency	Account​ currency
openDate	Account​ opening date
active	Account​ active

Transfer
source	Source ​Account​ Identifier
destination	Destination ​Account​ Identifier
amount	Amount to be transferred from ​source​ to ​destination
description	Transfer​ description (p.e. “Salary November 2018”)
timestamp	Date and Time of the ​Transfer

Please implement the following services:

• Account - Endpoint (​http://localhost:8080/Account​)

  • Create, Read, Update and Delete

• Transfers - Endpoint (​http://localhost:8080/Transfer​)

  • Create, Read
  • Execute Transfer

• Please ensure that the services implement the following business rules:

  • Transfer​s can only be made between two active ​Accounts​
  • Transfer​s can be made between different currency ​Account​s. If a ​Transfer​ is done between two different currencies, the specific currency is defined by the destination ​Account​ and the exchange rate is got from: o https://api.exchangeratesapi.io/latest?base=&symbols= (p.e. https://api.exchangeratesapi.io/latest?base=GBP&symbols=EUR​)
  • Every m minutes all the ​Account​ balances are updated due to an Operational Banking Tax. This Tax details (rate and recurrence) should be defined in the configuration file.
  • Account​ AccountId is an internal field that shouldn’t be visible in the Read operations, instead the Account​ IBAN should be shown (and generated during Account creation)
  • The application should respond to REST commands on the specified Endpoints and the READ operations should provide sort and filter parameters (at least) by the following fields:
    • Account​: ​IBAN​, ​Balance​ and ​Currency
    • Transfer:​ ​Source​, ​Destination​ and ​dateTime
  • The application should be able to read on startup two CSV files from an input folder named “input” defined in the configuration which are define in the resource folder src/main/resources/input

Prerequisite

In order to install and start the application please ensure that you have the following:

• Java JDK (v8+)
• Maven (v3+)
• MySQL (optional MySQL Workbench)

Instructions

1. The code can be found in github repo financial-service

2. Clone repository locally using

   git clone https://github.com/garytxo/financial-service.git

3. Install dependencies and run test

   cd financial-service

   mvn clean install

4. Start your server using

   cd financial-app

   mvn spring-boot:run

5. To view the REST API endpoints check the swagger documentation http://localhost:8080/swagger-ui.html

Change H2 to Mysql database

By default the application is configured to run against H2 database, in order to change to run against mysql please following the instructions below:

1. create the financial database schema by opening a terminal and executing the following command

   `mysql -uroot -Bse'CREATE DATABASE financial'`
   

2. Update the application-mysql.properties connection details

3. Change the active profile to ``mysql` in the application.properties

   spring.profiles.active=mysql

API USAGE

The following are a list of useful API usages one can perform

• Create a new account The following will create a new bank account with 100 euros deposit curl -X POST "http://localhost:8080/Account" -H "accept: */*" -H "Content-Type: application/json" -d "{ \"balance\": 100, \"currency\": \"EUR\"}"

• Update an account status or currency : curl -X PUT "http://localhost:8080/Account/MC242531931898PO86I8BD25Q26" -H "accept: */*" -H "Content-Type: application/json" -d "{ \"currency\": \"USD\"}"

• Delete an account by the IBAN number curl -X DELETE "http://localhost:8080/Account/MC242531931898PO86I8BD25Q26" -H "accept: */*"

• Find all account with currency EUR and order by balance desc curl -X GET "http://localhost:8080/Account?currency=EUR&orderBy=balance&sortOrder=desc" -H "accept: */*"

• Find all account with balance of 100 EUR and order by currency descending curl -X GET "http://localhost:8080/Account?balance=100&currency=EUR&orderBy=currency&sortOrder=asc" -H "accept: */*"

• Create a transfer between to valid accounts which has not been executed curl -X POST "http://localhost:8080/Transfer" -H "accept: */*" -H "Content-Type: application/json" -d "{ \"amount\": 100, \"description\": \"Party at the Ritz\", \"destination\": \"AT931551366098047339\", \"source\": \"GB14HFLH31198266710918\"}"

• Find all transfers curl -X GET "http://localhost:8080/Transfer" -H "accept: */*"

• Find transfer by for a certain destination account id and order by source desc curl -X GET "http://localhost:8080/Transfer?destination=GB09LUGV58378718496633&orderBy=source&sortOrder=desc" -H "accept: */*"

• Execute a transfer curl -X PUT "http://localhost:8080/Execute-Transfer/1" -H "accept: */*"

Discussion

• Implemented using Java 8 and artifacts are managed by gradle

• Frameworks used

  • spring boot starter kits
  • mockito & junit test
  • hamcrest
  • swagger -> REST API documentation
  • Super CSV -> csv import

• swagger for REST documentation

• Spring ControllerAdvice for exception handling

• javax Validator for entity field validation

• create a HandlerMethodArgumentResolver deal with authenticating the logged user

• Decided to use a TTD approach to solve this challenge

• Separate the business logic and DTO in a different artifacts

Things I could look for future enhancements

• Use flyway to manage database changes
• Could use spring security to enhance the user authentication
• JWT could be used to store the authenticated user credentials
• Enhance the customize search
• Consider using the JSR 354: Money and Currency API which might make it for JDK 9