Currency Tracker API

Project: Currency Tracker (API for web application)

Description This repository contains the backend API for a future web application that monitors and compares currency exchange rates gathered from several exchange platforms. The API provides current exchange rates, historical data, platform metadata, user management, real-time notifications via WebSocket, and report generation (XLS).

---

Key Features

• Fetch current exchange rates from external sources (APIs or scraping).
• Compare rates across multiple exchange platforms.
• Store and serve historical exchange rate data for analysis.
• Filter data by currency pair and time range.
• Real-time notifications about rate changes using WebSocket.
• Generate XLS reports based on selected data and time ranges.

---

Non-functional Requirements

• Performance: Real-time data processing with minimal latency.
• Reliability: Stable updates and graceful handling of external service failures.
• Scalability: Easy to add new data sources or currency pairs.
• Security: Restrict access to sensitive data and protect the API from unauthorized use.
• Usability: Clear and intuitive endpoints for frontend consumption.

---

Project Structure (important folders)

• api-for-exchangers-java — Java backend service.
• api-for-exchangers-python — Python backend service (FastAPI).
• api-for-exchangers-web-client — simple web client for testing WebSocket (contains WebSocket.html).
• DB/backup_dev/ and DB/backup_prod/ — MongoDB backup dumps.

---

Prerequisites

• Java (JDK) installed for the Java server.
• Python 3.9+ and pip for the Python server.
• MongoDB running locally at localhost:27017 (or update connection string in configuration).
• mongorestore utility if you want to import provided database dumps.

---

Local Setup & Run

1. Start MongoDB (local instance):
   • Ensure MongoDB is running on localhost:27017.
   • If databases currency_tracker_db_dev and currency_tracker_db_prod are missing, restore them from backups:

mongorestore --db=currency_tracker_db_dev backup_dev/currency_tracker_db_dev
mongorestore --db=currency_tracker_db_prod backup_prod/currency_tracker_db_prod

2. Run Java server

   • Path: api-for-exchangers-java
   • Start the Java server according to the project README/build script (build with Maven/Gradle where applicable).
   • The Java server exposes REST endpoints on port 8080 by default.
   • To stop the Java server you can use your terminal/IDE stop command.

3. Run Python server (FastAPI)

   • Path: api-for-exchangers-python
   • Start the server with Uvicorn from the project folder:

uvicorn main:app --reload

• Python API is available on port 8000 by default.

4. WebSocket test client
   • Open api-for-exchangers-web-client/WebSocket.html in a browser.
   • Click Connect, enter the currency pairs you want to monitor, then click Subscribe.

---

Important API Endpoints

Use ?environment=prod to switch calls to production profile where supported.

• Get all exchange rates (Java):
  • http://localhost:8080/api/exchange-rates
• Get all exchange rate histories (Java):
  • http://localhost:8080/api/exchange-rate-history
• Get all exchange platforms (Java):
  • http://localhost:8080/api/exchange-platforms
• Get all users (Java):
  • http://localhost:8080/api/users
• Get all reports (Java):
  • http://localhost:8080/api/reports

API documentation pages:

• Java Swagger UI: http://localhost:8080/swagger-ui/index.html
• Python (FastAPI) docs: http://localhost:8000/docs

---

Data Model (MongoDB collections)

• ExchangeRate — current exchange rate data (currency pair, buy/sell rates, last update timestamp).
• ExchangeRateHistory — historical changes for currency pairs (with timestamps).
• ExchangePlatform — metadata about tracked exchange platforms (name, API url / parsing url).
• User — application users and their notification settings/subscriptions.
• Report — generated reports metadata (creation date, currencies, time range).

The project is designed with MongoDB document collections to preserve flexibility (JSON/BSON documents with optional nested fields).

---

WebSocket Notifications

• Real-time notifications are implemented using WebSocket.
• Use the included WebSocket.html client to simulate subscriptions: connect → subscribe to currency pairs → receive updates.

---

Report Generation

• The API supports generating XLS reports for selected currencies and time ranges. The result is stored as a Report object and can be downloaded or accessed by the frontend.

---

Notes & Troubleshooting

• If external source requests fail, ensure API URLs for exchange platforms are correct and reachable.
• Monitor logs (Java and Python services) to diagnose integration issues with external providers.
• When switching between dev and prod profiles, remember to add the ?environment=prod parameter to requests if needed.