README.md

Introduction

This project is a messenger-like chat application designed for scalability. We use docker to simulate the environment of using multiple node for production deployemnt.

We use Node.js as a back-end server to provide api for the front-end web application. MongoDB cluster is used as the main database and Redis is used as a temporally storage like cache and shared session. The engine for real-time chat is implemented on Socket.io. The architecture of distributed system are shown below.

There are totally eight nodes of the server. The first one is NGINX which is load balancer of the system. The next one is web application server node which is implemented with Angular2. Besides, there are two api server implemented using Nodejs, api_primary and api_secondary. Also, cache is used in this as a share memory. It is run using Redis. Lastly, a permanent storage, mongodb cluster which contains the cluster of the replica for fault torelant reason.

Prerequisites

• Node.js 7.9.0

Note: nvm is recommended, so you can run nvm use to use recommended version of Node.js.

• Yarn 0.23.2 or higher
• Docker Community Edition 17.03.0-ce or higher
• Docker Compose 1.11.1 or higher
• Angular CLI 1.0.0 (installed globally)

Introduction to Yarn

We use Yarn package manager instead of npm because it is faster and have better reliability on dependencies versioning. Do not forget to use yarn instead of npm.

Note that, in addition to package.json file, we also have yarn.lock file, which is generated/edited on running yarn command. For any changes to dependencies, do commit changes in yarn.lock along with the changes in package.json file.

Useful Commands

Command	Description
yarn or yarn install	Install all packages listed in package.json.
yarn add express	Install package express and add as dependencies to package.json. This is equivalent to npm install --save express.
yarn add --dev express	Install package express and add as devDependencies to package.json. This is equivalent to npm install --save-dev express.
yarn remove express	Uninstall package express and remove from package.json. This is equivalent to npm uninstall --save/--save-dev express.
yarn global add @angular/cli	Install package @angular/cli globally on your machine. This is equivalent to npm install --global @angular/cli.
yarn run test:all or yarn test:all	Run script test:all as writen in package.json file. Note that unlike the npm , you can also omit the run keyword.
yarn outdated	List all the outdated package, i.e. the locally installed package that has a newer version.

You can have a further read on the commands in Yarn's Docs.

Getting Start

To start front-end development, change directory into web app and then run yarn start

$ cd webapp   # change directory into webapp
$ yarn start  # run front-end environment with yarn

For back-end side, we have to option for you. The first one is run all necessary container development. To run this, following the instruction below.

$ cd api   # change directory into webapp
$ docker-compose up --build  # run front-end environment with yarn

The other option is running docker as distributed system. To run this environment, the commands has to be modified as followings.

$ cd api   # change directory into webapp
$ docker-compose -f docker-compose.prod.yml up  # run production file