xtrycatchx/mr-takehome

Take Home

Overview

There are 6 components in this architecture

component	purpose	dependency
cache-service	Exposes APIs for fetching globally unique random numbers from cache. This also processes unused numbers by putting it back to cache	redis for caching
buy-service	Processes transaction when someone buys a number	mysql to update the number, redis to publish event to listeners
history-service	Exposes an API to get history of a number. Listens to events from redis to update the number in db.	mysql to store history, redis to subscribe events
redis	Caches temporary data. Serves a messaging hub between buy-service and history-service
mysql	Stores numbers and its status. Stores historical transactions concerning numbers
frontend	Dummy client to display globally random numbers available. Allows end-user to buy a number. Simulates a logout/timeout which will return the random numbers back to cache-service.	cache-service for available numbers, buy-service for buying a number/s

Getting Started

These instructions will get you a copy of the project, have it up and running on your local machine for demo purposes.

Prerequisites

You need at least Docker or best if you have setup Kubernetes. You can check my short blog post for a quick 1 cluster K8s setup : https://www.not.expert/blog/local-development-with-kubernetes

Installing

A step by step to run this stuff

MySQL

Assuming you already have mysql instance running, you may need to create schema and table

CREATE SCHEMA `numbers_db`

Create the numbers table

CREATE  TABLE `numbers_db`.`tbl_number` (
  `id` INT NOT NULL AUTO_INCREMENT ,
  `number` VARCHAR(45) NULL ,
  `status` VARCHAR(45) NULL ,
  `added` DATETIME DEFAULT CURRENT_TIMESTAMP ,
  `lastUsed` DATETIME NULL ,
  PRIMARY KEY (`id`) );

Create Transaction History table

CREATE TABLE `tbl_history` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `time_stamp` datetime DEFAULT CURRENT_TIMESTAMP,
  `number_id` varchar(45) NOT NULL,
  `transaction_type` varchar(45) DEFAULT NULL,
  PRIMARY KEY (`id`)
);

Build and Run Redis

cd redis-cache-image
./docker-build.sh
./docker-run.sh

Run Cache Service

Setup first the env variables accordingly in file number-cache-service/env.list

key	description
SERVER_PORT	port that this service listens to
REDIS_CACHE_KEY	key for our transient records

You can start the service by executing the following

cd number-cache-service
./run-locally.sh

End with an example of getting some data out of the system or using it for a little demo

Run Buy Service

Setup first the env variables accordingly in file number-buy-service/env.list

key	description
SERVER_PORT	port that this service listens to
MYSQL_HOST	mysql host / ip address
MYSQL_USER	mysql user
MYSQL_PASSWORD	mysql password
MYSQL_DB	default schema
MYSQL_CONNECTION_LIMIT	number of conneciton limit. leave as is.
MYSQL_DEBUG	you can switch to true or false depending on your need
REDIS_AUTH	Password of the redis instance so this service can publish events

You can start the service by executing the following

cd number-buy-service
./run-locally.sh

Run History Service

Setup first the env variables accordingly in file number-history-service/env.list

key	description
SERVER_PORT	port that this service listens to
MYSQL_HOST	mysql host / ip address
MYSQL_USER	mysql user
MYSQL_PASSWORD	mysql password
MYSQL_DB	default schema
MYSQL_CONNECTION_LIMIT	number of conneciton limit. leave as is.
MYSQL_DEBUG	you can switch to true or false depending on your need
REDIS_AUTH	Password of the redis instance so this service can subscribe to events

You can start the service by executing the following

cd number-history-service
./run-locally.sh

Run FrontEnd

You can start the front end by executing the following

cd number-frontend
npm install && npm start

Use the App

Open a browser and navigate to http://localhost:3000 Once landed, you will see a randomized numbers which are clickables.

• Clicking on a number will simulate Buying of a Number. It will hit backend and eventually MySQL and flag that record so it won't be served to Redis for randomization
• Clicking on Simulate Fetch Randomizer will ask Redis for another set of random numbers that can be bought. These numbers are considered blocked and won't be served elsewhere.
• Clicking on Simulate Logout or Timeout will push back the remaining numbers not bought back to Redis, to be served again to another customer.