EchoAtTime

A simple application server that prints a message at a given time in the future. Uses Redis to persist messages in case of failure.

Installation

Prerequisites

To run the app you will need Node.js (8.12.0 or newer) and Redis (4.0.11 or newer)

$ npm install

OPTIONAL: configure the app

The app can be configured through the files in the config folder (see https://www.npmjs.com/package/config)

If you are going to run multiple instances of the app simultaneously and connect them to a single Redis instance/cluster, you should specify unique names for the 'In Progress' set in Redis for each server in the config: config.redis.inProgressSet. That way each instance of the app will work on its own 'In Progress' set.

Run the app

$ npm start

Test the app:

• npm run test:unit - will run unit tests.
• npm run test:acceptance - will run acceptance tests.

NOTE: the acceptance test suite requires a running app server and a Redis server.

API documentation

POST http://localhost:3000/api/v1/echo

Schedules a message to be printed out in console on a specific time in the future.

• Request body params (JSON):

  • time (REQUIRED) - Number

  Time when the message should be printed represented by the number of milliseconds elapsed since January 1, 1970 00:00:00 UTC. Should be greater than current time but not more than a year from now.

  • message (REQUIRED) - String

  A string to print in the console. Should not be empty.

• Responses:

  • 202 Accepted
  • 400 Bad Request (also contains an array of errors in the response body)

Note: possible improvements

• Use Redis SortedSets instead of Sets?
• Integration tests for the Redis client