Planet backend-assignment

Backend position skill assessment home assignment.

Context

As a Full-Stack developer in Planet Dataset, you will be asked to participate in the design and implementation of new features that will be used in our price-management platform for eCommerce.

New features are geared towards automations and, in our pletform, developing them usually involves three different tasks:

1. Implementing an interface to configure the user's preferences.
2. Implementing API endpoints to retrieve data such as result examples.
3. Implementing asyncronous tasks that apply the changes to our clients' stores.

This is the workflow that we tried to replicate in this task. The theme is forex analysis, and we will require you to implement an API call to retrieve currencies from the database, an asynchronous task to retrieve the data from an external API, and the interface to subscribe and list different currencies.

Overview

This repository holds the basic project structure for implementing a NodeJS based API and service used in a fictitious software solution that provides stock exchange data services. The front-end is an Angular app with an NgRX store in case you prefer it for state management.

Disclaimer: The purpose and usage of this repo is solely for insight adquisition regarding problem-solving, and does not represent an existing and ongoing implementation task.

PD: We provide this structure as an starting point but you may discard it and approach the task in any other way.

The problem

The solution you are required to design and implement is geared towards collecting historic exchange prices from the currencies the API user wants to EUR. With this in mind we need a system that provides an API for adding, removing and listing the currencies that are being followed at the moment, and an additional endpoint for retrieving such historic data.

The workflow that the system should support is:

1. The API user adds or removes currencies from the followed ones, by the currency code.
2. The API user is able to see the followed currencies using the corresponding endpoint
3. The system, periodically, fetches the stock exchange price from each followed currency to Euros (EUR).
4. The API user can retrieve the historical data for a subset of the followed currencies, which includes basic data such as ask, bid, and spread; and additional calculated stats.

We recommend using the alphavantage API for retrieving the data as it is free and the endpoint for retrieving the data is well documented and easy to use. See the docs: https://www.alphavantage.co/documentation/#crypto-exchange

Tasks

The required functionality can be summarized in the following four tasks:

• Implement an endpoint for retrieving the exchange price history of the followed currencies. This endpoint must allow specifying the currencies to be included and the fields to include; at least the following fields must be included: bid, ask, spread, bid-diff (the difference between the bid and the previous hour mean bid), ask-diff (the difference between the ask and the previous hour mean ask), and spread-diff (the difference between the spread and the previous hour mean spread).
• Implement the periodic historic data retrieval.
• Implement the interface to list, follow and unfollow currencies.
• Implement the interface to list the exchange price history of the followed currencies.

Evaluation

We are in search for a backend developer who is capable of implementing API requirements, can work databases and can design "future-proof" (if that even exists) solutions.

Therefore we will evaluate the assignment having the following things in mind:

• Home assignment completition: Whether you completed all tasks and how you prioritized time.
• Code versioning: We are not too picky regarding Git, but do appreciate feature branchs and a clean repo history that could help us understand how you approached this assignment.
• Task-specific implementation details:
  • Currency endpoints implementation. We would appreciate it if you took into account the following aspects: How would you document the API?, What would happen if we wanted to support newer data sources?
  • Price history endpoint. We would appreciate it if you took into account the following aspects: How would you allow the user to specify a time range? What would happen if we wanted to support more statistics?
  • Periodic data retrieval. We would appreciate it if you took into account the following aspects: What would happen if we wanted to support more types of data sources?
• Extras: Providing extra documentation, identifying any improvement opportunity (even if you didn't implement it), or having a fluent communication during your process (just let us know how you are doing) will be positively taken into account.

Repository structure

The code is laid down in a monorepo fashion with make commands for easier admin tasks. The two services that you can find find are the api and service services.

The api service is an Express server with hot code reloading, while service generic service with a Node setup that runs the script periodically and that you may use -or not- for any recurring process; this later service can be run manually without the cron job.

You can use the make command (from the root directory) to run the platform. We have set it up for two main use cases:

• Having the API up (with hot-reloading), along with the generic service (without hot-reloading) running periodically using cron:

  make backend-up

• Having the API up (with hot-reloading) without the generic service. You can then execute the generic service once or have it execute each time the code has changed:

  make backend-up-slim
  # execute the generic service once
  make service-run
  # execute the generic service each time the code changes (hot-reloading)
  make service-dev

Following is a more-in-depth list of the available command for each service:

• The services/api directory holds the code for the API. The following make commands are available:

  • backend-build Builds the corresponding Docker images.
  • backend-up Raises the platform.
  • backend-up-slim Raises the platform without the service service running in the background (just the db and API).
  • backend-down Shuts down the platform. Requires having the platform up (you can use make backend-up)
  • backend-dump Dumps the database contents to a dump folder. Requires having the platform up (you can use make backend-up)
  • backend-load Loads the database contents from a dump folder. Requires having the platform up (you can use make backend-up)
  • backend-dbshell Connects to the database shell. Requires having the platform up (you can use make backend-up)
  • backend-test Runs the API tests with database dump and restore. Requires having the platform up (you can use make backend-up)

• The services/services directory holds the code for the API. The following make commands are available:

  • service-build Builds the corresponding Docker images.
  • backend-run Executes just once the service.. Requires having the platform up (you can use make backend-up)
  • backend-dev Executes the service each time the code changes. Requires having the platform up (you can use make backend-up)

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backend-assignment

Backend position skill assessment home assignment.

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