Chat Server

A chat server based on the microservice architecture to ensure high availability, high throughput, horizontal scalability.

Architecture

Components

• Nginx: Nginx act as API gateway as well as load balancer.

  • Responsibility
    • API Gateway
    • Authentication
    • Load Balancing

• Web Socket Gateway: It's handling client websocket connection and sending message to message broker

  • Responsibility
    • Maintaining Web Socket Connection
    • Forwarding event like onConnect, onDisconnect, new-message to message broker
    • Sending message back to client

• Rest Http Gateway: It handle rest call to send messages.

  • Responsibility
    • Send Message to message broker.

• Profile MS: Rest Api Service provides functionality like login, auth, contact-sync

  • Responsibility
    • Login, Auth
    • Contact Sync

• Group MS: Rest Api Service provides functionality to create, update

  • Responsibility
    • Create Group
    • Add, Remove Members
    • Fetch groups

• Message Delivery MS: Message delivery in real time when the user is connected, syncing messages when user is offline

  • Responsibility
    • Maintaining User connection state.
    • Message push in real time when a user in connected.
    • Store message when the user is disconnected.
    • Guaranteed message delivery to the receiver.
    • Ability to sync message in background.

• Message Router: Route the incoming new message to respective destination

  • Responsibility
    • Parse message.
    • Redirect message to respective destination for e.g.
      • Route group message to Group Message Router.

• Group Message Router: Route the incoming group messages to respective destination

  • Responsibility
    • Fetch group users for particular user.
    • Update message meta with user list.
    • Redirect Message to respective destination.

• Push Notification: Deliver message to user when user is offline

  • Responsibility
    • Deliver message to offline user

Message Format

{
    "_v": 2.1,
    "id": "string",
    "head" : {
        "type": "chat|group|channel|bot|notification",
        "to": "username|group_id|channel_id|bot_id",
        "from": "username",
        "chatid": "chatid", // to be deperciated, added for backward comptibility only,
        "ephemeral": "true/false",
        "category": "user|system",
        "contentType": "json|text|video|audio|location|form",
        "action": "message|ack|subscribe|unsubscribe|join|leave|create|add-member|remove-member"
    },
    "meta": {
        "hash": "md5:hash",
        "content_hash": "md5:hash",
        "generate_ts": 123455667890
    },
    "body": {
        "text": "Hello this a text message",
        "ts":123455667890
    }
}

{
    "_v": 2.0,
    "id": "string",
    "head" : {
        "type": "chat|group|channel|bot|notification",
        "to": "username|group_id|channel_id|bot_id",
        "from": "username",
        "chatid": "chatid", // to be deperciated, added for backward comptibility only
        "contentType": "json|text|video|audio|location|form",
        "action": "message|ack|subscribe|unsubscribe|join|leave|create|add-member|remove-member"
    },
    "meta": {
        "hash": "md5:hash",
        "content_hash": "md5:hash",
        "generate_ts": 123455667890
    },
    "body": {
        "text": "Hello this a text message",
        "ts":123455667890
    }
}

Mapping with previous Message format

{
    "msgId": "id",
    "from": "head.from",
    "type": "head.content_type",
    "to": "head.to",
    "chatId": "head.to",
    "text": "body.text",
    "state": "n/a",
    "module": "head.type",
    "action": "head.action",
    "chatType": "head.type"
}

Directory Structure

Name	Description
.github	Configuration files related to github like workflows, funding
.gipod	Configuration files for gitpod dev enviroment setup
.husky	git hooks configuration via husky
deployment	Deployment scripts
docs	Docs related to the project
helper	Common utility functions
libs	Project specific libs like base class for microservice, resource configuration and initialization
services	Microservice
www	Web based testing interface
.env.tmpl	Environment template file
.gitpod.yml	Gitpod configuration file
LICENSE	Project License file (MIT)
package.json	Node project configuration file
README.md	Project description and other details

How to setup

Use Gitpod as development environment

Click on the Gitpod badge it will start the fully setup development environment.

Development environment on local machine

Prerequisites

• Apache Kafka / Nats
• Mongodb
• Nginx
• Firebase project
• Redis

Steps

• Clone the master branch of the project

• Install dependencies

  npm install 
  

  Or

  yarn install 
  

• Make copy of .env.tmpl to .env and update the required variables

  cp .env.tmpl .env
  

• Initialize Message Broker

  cd deployment/scripts
  

  Setup Kafka

  ./init-kafka.bash ${KAFKA_INSTALLATION_DIRECTORY} .env
  

  OR

  Setup Nats

  ./init-nats.bash .env
  

• Open project in vscode

• Start the required microservice from RUN and DEBUG option

• (Optional) Start nginx using the configuration deployment/config/nginx.config

Deployment

For deployment guide refer to deployment/README.md.

Resources

API specs doc

• API documentation here

• Open API specs 3.0 here

Blog posts

To follow the update keep a eye on vartalap blogs on blog.one9x.org Some of the relevent blogs are:

• Vartalap: Open Source Personal Messaging App
• Vartalap: Chat Server Architecture V1
• Vartalap: Chat Server Architecture V2
• Vartalap: Chat Server Architecture V2.1

LICENSE

MIT