afijog / market-price-handler

My contributions

A few words, on how the project is structured, how to improve it (TODO actions) and finally how to test, build and execute it.

Design

The main project delegates functionality to several services. Mainly:

• fx.controller: Classes to expose functionality as a REST service.
• fx.model: The POJO and standard model classes
• fx.service.broker: The broker to get data from feed, adjust prices and expose them to other modules
• fx.service.feed: Interface for subscribers and base 'hardcoded' FX price feed
• fx.service.parser: Parses a message line and converts to a POJO object model

Improvements

• Use effects library (ZIO, Cats) to decouple the logic of the program from the execution. This is more Scala oriented
• If using files for price information, use streaming of big files instead of reading the whole file at once
• Read format of timestamp from properties file
• Add more JUnit tests
• Add integration tests
• Improve error handling (again using effects, Optional, Either)
• Externalise price information for feed object
• Use log functionality (logger.info, logger.error...)
• Use immutable data objects (useful for concurrency, threads)
• Decouple the caller/callee using queues and Producer/Consumer strategies
• Follow Reactive Manifesto (https://www.reactivemanifesto.org) and Twelve-Factor (https://12factor.net) principles

Build the project

Before building the project it is a good idea to run the tests to check if everything is ok. Some unit test are provided. To run them, execute the following command:

mvn clean test

Note: You can use also mvnw as the basic command to invoke Maven actions.

If everything is ok, you can proceed with the build process.

Execute the following command:

mvn clean package

You got a fat jar that is easy to execute and deploy. Manually or using CI/CD techniques (docker images for instance)

Run the project

Execute the following command:

java -jar target/fx-1.0.0.jar

Open your favourite browser and go to

http://localhost:8080/price/EUR-USD

Note: The currency pair is using '-' instead of '/' to be treated as a unique parameter. The application will take care of that.

How to proceed from this point

Review the code and tell us if you have any doubt. I will be more than happy to discuss this implementation and talk about changes and improvements.

Documentation

Reference Documentation

For further reference, please consider the following sections:

• Official Apache Maven documentation
• Spring Boot Maven Plugin Reference Guide
• Create an OCI image
• Spring Web
• Thymeleaf

Guides

The following guides illustrate how to use some features concretely:

• Building a RESTful Web Service
• Serving Web Content with Spring MVC
• Building REST services with Spring
• Handling Form Submission