Stock-ticker

Introduction

Simple REST API provides stock ticker data for required securities based on Node.js and Redis.

Feeder for it was implemented in https://github.com/DariuszWietecha/stock-ticker-feeder.

Endpoints

1. Get securities list

• Request:

  Method: GET

  URL: https://example.com/symbols

• Response example:

[
  {
    "description": "APPLE INC",
    "displaySymbol": "AAPL",
    "symbol": "AAPL"
  },
  {
    "description": "MICROSOFT CORP",
    "displaySymbol": "MSFT",
    "symbol": "MSFT"
  }
  ...
]

2. Get ticker data for required securities

• Request:

  Method: GET

  URL: https://example.com/tickers/{symbol 1st}/{symbol 1st}/...{symbol n}

Ticker data is available only for stocks listed in response from Get securities list endpoint.

• Response example for https://example.com/tickers/AAPL/MSFT:

[
  {
    "p": "314.4",
    "s": "AAPL",
    "pc": "314.96",
    "t": "1589930233941",
    "v": "5",
    "cd": "down",
    "ca": "-0.56"
  },
  {
    "p": "183.98",
    "s": "MSFT",
    "pc": "184.91",
    "t": "1589930239480",
    "v": "5",
    "cd": "down",
    "ca": "-0.93"
  }
]]

Meaning of the attributes:

Attribute	Attribute name	Description
p	Price Traded	The price per share for the particular trade (the last bid price).
s	Ticker Symbol	The unique characters used to identify the company.
pc	Previous close price	Close price from previous day.
t	Timestamp.	UNIX milliseconds timestamp of the last trade.
v	Shares Traded	The volume for the trade being quoted.
cd	Change Direction	Shows whether the stock is trading higher or lower than the previous day's closing price.
ca	Change Amount	The difference in price from the previous day's close.

Implementation details

API and feeder were implemented as separate services to increase the reliability of the first.

API use Redis database and cache Get ticker data for required securities endpoint for 1000 milliseconds to be able to handle a big load.

The API holded on 1100 stock-ticker-100.herokuapp.com/tickers/AAPL/GM/INTC/MSFT/NKE/NVDA/TSLA requests per second for 1 min with 0.0 % err rate and 310 ms avg resp - details of the test.

Source of real US stocks trade data is Finnhub API.

Used dependencies:

• @hapi/hapi
• redis-connection
• ws
• dotenv
• @hapi/code
• @hapi/lab
• rewire
• sinon

During the implementation was used node v12.0.0.

Running the app

Running localy

1. Install dependencies using

npm install.

2. Copy example.env as .env and update it with real passwords and Redis instance host. To change the host/port to different than 0.0.0.0/8080 add HOST and PORT variable to the .env file.
3. Run app using

npm start.

4. The App will be available on http://0.0.0.0:8080(If host/port wasn't changed by .env).

Running in the docker container

1. Copy example.env as .env and update it with real passwords and redis instance host. To change the host/port to different than 0.0.0.0/8080 add HOST and PORT variable to the .env file.
2. Install Docker.
3. Build the image:

docker build -t stock-ticker .

4. Run image:

docker run --env-file .env -p 8000:8080 stock-ticker (windows)

docker run --env-file ./env -p 8000:8080 stock-ticker (linux)

5. API will be available on http://localhost:8000(or another host proper for your docker).

Unit tests

Coverage: 95.79%

Running tests

1. Install dependencies and build using npm install.
2. Run unit tests by npm test.
3. To check test coverage run npm run test-cov or test-cov-html(It creates a report in coverage.html).

Notes

• .vscode directory was committed to the repository to let to debug the workflow execution and unit tests execution in VSCode.