MicronautBroker

Simple RESTful API for managing BTC trading requests using the Micronaut framework. There is no authentication in this application, while the API only managers request to create accounts and buy assets (BTC).

A simple Flask service producing BTC/USD prices is included

$pip install -r requirements.txt
$python exchange.py

The endpoint providing quotes is located at http://127.0.0.1:5000/btc-price

All API calls are implemented as GET requests. The following endpoints are exposed at http://localhost:8080/broker

• /account/create/{name}/{usdBalance}: Creates an account for the given person and provided USD balance
• /account/get/{accountId}: Gets information about the account identified by accountId
• /order/create/{accountId}/{priceLimit}/{amount}: Creates a new order for the account identified by accountId. The limit price as well as the amount of BTC to buy are provided
• /order/get/{orderId}: Gets details and status about the order identified by orderId
• /order/all: Returns the details and status of all orders

Examples

1. broker/account/create/marc/10000: create a new account for the user "marc" with balance $10,000. The account id is returned
2. broker/order/create/1/9000/2: create a new order for account 1. The price limit is $9,000 and the amount of Bitcoins to be purchased is 2.

In other words, account 1 must have a balance of at least $18,000 in order for the order to be executed. Three things may happen:

1. the current price is larger than $9,000: the order remains in PENDING state;
2. the current price is at most $9,000 and the account has a balance of at least $18,000: the order is marked as FILLED, the Bitcoin balance is increased by 2 and the USD balance is decreased by $18,000
3. the current price is at most $9,000 and the account has a balance of less than $18,000: the order is marked as CANCELLED and nothing else happens

Implementation details

1. The PriceCheckerTask background task is used to poll the provided price service every 2 seconds (localhost/port 5000). A simple implementation of the circuit breaker pattern is used in case the price service is not available.
2. Pending orders (the order book) are stored in a (max) heap. Every time a new price is available, all orders whose limit price is larger or equal than the price are executed (if the account balance is sufficient)

Testing the code

./gradlew build

Running the service

./gradlew run