Property Finder Educational Side Project

Summary

This is an educational side project where I am trying to replicate a real world marketplace app, like Blocket, Realtor or PropertyFinder, where users can buy and sell used apartments. The idea is to create a very simple initial version of it and iterate over the time adding new features and use cases, documentating the process and enabling discussions about scalability, availability and performance.

Functional Requirements

• Users can register to create new accounts and use the system
• Users can authenticate in the app using JWT strategy
• Authenticated Sellers can add new properties to the listing
• Buyers can search for existing apartments using plain text or keywords
• Authenticated Buyers can create monitors to specific search keywords
• Buyers should be notified about new properties every 24hs and should never be notified twice about the same property.

Non-Functional

• User authentication should be safe and reliable
• Low latency on search results
• Eventual consistency of new apartments on search results
• General high availability and scalability

High-Level System Design

• Web Server: Nginx web server responsible about host and delivery the client React web app, it will also cache requests, and apply rate limits to prevent DDoS attacks.
• API Gateway: REST API Gatweay to all internal micro services. It is responsible about handling user authentication, validate session and proxy authenticathed api calls to internal services.
• Identity Service: Internal service used to Register and Authenticate users.
• Property Service: Internal service used to maintain user properties.
• Search Service: Internal service used to search by properties in the Elasticsearch index.
• Keywords Service: Internal service used to maintain active search keywords monitors.
• Search-Indexer Consumer: AMQP service used to consume "new property" events from Kafka and update the search index.
• Notification Consumer: AMQP service used to consume "new property" events from Kafka and insert pending notification into a Redis datastore with a TTL.
• Notification Service: This service will read the list of pending notifications from Redis and send batches of email notifications.

API Design

Method	Endpoint	Access	Description	Return
POST	/api/v1/accounts/register	Public	Register a new user account in the app	200, 4xx
POST	/api/v1/auth/login	Public	Authenticate the user, create cookies and return user info	200, 401
GET	/api/v1/auth/me	Protected	Validate session and get user info	200, 401
POST	/api/v1/auth/logout	Protected	Logout existing the user, remove cookies	200, 401
POST	/api/v1/properties	Protected	Create a new property	201, 4xx
GET	/api/v1/properties/<id>	Protected	Return details from a single property	200, 404
PUT	/api/v1/properties/<id>	Protected	Update one existing property	200, 404
DELETE	/api/v1/properties/<id>	Protected	Delete one existing property	200, 404
GET	/api/v1/properties/search?q=<keyword>	Protected	Full-text search on indexed properties	200

Database Schema

User Authentication Flow

Use cases

1. User Sign-in in the app
2. Authenticated user perform an API call to protected resources using a valid access token
3. Authenticated user perform an API call to protected resources using an expired/invalid access token
4. Authenticated user perform an API call with both Access and Refresh Token expired

Implementation details

The Monorepo

CI & CD

I am using Github Actions with a standard pipeline definition for NX monorepos. Only CI for now but I have plans to setup the CD at some point to deploy the app to staging and run E2E tests.

Backend

Frontend

TBD

Testing strategy

TBD

Deployment

TBD

Local Development

Start the app

You can run all services by starting the docker-compose

docker-compose up

Lint and Tests

nx run-many -t lint test