Overview

This microservice is responsible for sending notifications to user devices in response to an event coming from the notification scheduler. This microservice also takes care of user-device registration and deregistration.

• Before receiving reminder-notifications users device(s) must be registered with the service so that it can send the notification to the device(s).
• Clients can register the user device using an FCM token generated from the project's cloud-messaging system. If the FCM token is valid then the device is registered otherwise not.
• Clients can also deregister the device using the provided device ID after successful registration, if the user wishes not to receive notifications on this device or on logout operation.
• These registration details are stored in PostgreSQL database.
• The incoming notification-event from the notification-scheduler contains all the information required to send the notification to the client.
• This service continuously polls the notification-sqs-queue and send the notification to the clients.

Operating Instructions

Fork

• Fork this repository
  • "Forking" adds a copy of adisakshya/notification-service repository to your GitHub account as https://github.com/YourGitHubUserName/notification-service
• Or you can download or clone this repository
  • You can clone the repository executing below command in a location of your choice in your system
  • $ git clone https://github.com/adisakshya/notification-service.git
• Source code for the notification-service can be found at /src
• All CI/CD resources are located in .travis directory
• requirements.txt contain the python packages required for the CI/CD process
• .env.example is a template env file

Local Development

Prerequisites

• Make sure you have
  • Installed Docker (when running using docker)
  • Firebase Cloud Messaging (FCM) service-account json file
  • PostgreSQL device-database running and accessible using host-url, username and password
  • AWS SES template
  • AWS SQS notification-queue setup and is accessible using queue URL
  • AWS SNS event-topic setup and is accessible using ARN

Using Docker

• In source directory src/ run the following command
  • $ yarn install - install required dependencies
  • $ yarn build - build source code
  • $ yarn test - run test (optional)
  • $ docker build -t notification-service . - build docker image
• With successful execution of above commands you will have a docker-image for the notification-service
• The docker-image can be run using the following command
  • docker run -p 3000:3000 --env-file ./.env notification-service
• On successful start, the notification-service is ready to consume notification-messages from the notification-queue

Without Docker

• Replace the env-variables at /src/src/common/api-config.service.ts
• Use the following commands to start the service
  • $ yarn install - install required dependencies
  • $ yarn test - run test (optional)
  • $ yarn start - start notification-service
• On successful start, the API documentaion (built using Swagger) for the service will be accssible on http://localhost:3000/docs

Architecture

Fig 1 - Notification Service Architecture

Clients can interact with the service using HTTP/HTTPs requests (interfaced by API Gateway) for device-registration while mechanism for sending notifications is internal. The notification-service has 2 modules namely:

• Device Module
  1. Device Controller - Handles incoming requests for device-registration and returns responses to the client
  2. Device Service - Defines the logic to serve incoming requests
• Notification Module - Polls the notification-queue and send available notifications to target clients

CI/CD and Deployment Guide

A brief description of the deployment strategy is described in documentation of continuous-improvement project.

Contributing

There are multiple ways to contribute to this project, read about them here.

License

All versions of the app are open-sourced, read more about this LICENSE.