marcinkrykowski / forex-proxy

Forex system proxy

Example microservice written in Scala using some modern FP libraries.

Disclaimer: This project serves as piece of my code. In production code there would be quite a few changes.

Table of Contents

• Use case
• How to run application locally
• Endpoints
• Example request
• Configuration
• Tests
• Assumptions
• Why I used http4s (library) over for example Play (framework)?
• Possible improvements

Use case

The use case in this system is quite simple. We want to use configurable forex system proxy to be independent of the underlying system that keep the actual values. We might use one system today and decide that we want to change it tomorrow. We don't

How to run application locally

As this project is a sbt application you can either import it to your IDE fo choice e.g. IntelliJ or execute sbt run from the rot folder. By default, the app serves traffic at localhost:8092.

Endpoints

Rest endpoints listed below:

Method	Url	Parameters	Description
GET	/rates	firstCurrency, secondCurrency	Returns latest currency rates from external source - API

Example request

Some example request that might be executed via curl or in browser http://localhost:8092/rates?firstCurrency=USD&secondCurrency=JPY

Configuration

The application might be configured by changing application.conf in resources. Things that might be changed are

• forex system that we use (currency rates provider)
• token (its name and value)
• application config (hostname and port used by the app)

Tests

To run tests execute sbt test. You will run all unit tests. To run integration tests start a Docker image by doing docker-compose up in root. After that run sbt it:test or run CurrencyServerSpec.scala from IDE.

Assumptions

Project has a few assumptions. The proxy does not validate whether the passed currencies are valid or not. User might pass not supported currency but the assumption is that the underlying Forex API will respond with appropriate message.

Why I used http4s (library) over for example Play (framework)?

It is much better to have full control over what's happening in my application than rely on some runtime magic and annotations. That's why I've chosen http4s library over Play. Might have used tapir, typedApi or akka-http as well.

Possible improvements

• Add Swagger integration for API documenting
• Add continuous integration
• Add property based testing