ETPZP SMS System

In May 2024, I independently completed my first medium-sized application: a web-based Flash SMS management system for ETPZP, my technical high school in Portugal, to replace expensive third-party SMS services. Sending, scheduling message delivery, contact management, auto-save drafts, recipient validation, and an admin dashboard with analytics and user rankings were among the most notable features. The school's staff now uses the system for urgent announcements. What began as a high school final project expanded into "almost a product that I could sell," as the jury commented at the end of my presentation. I built the project in TypeScript using the Next.js framework, with PostgreSQL for the database queried through raw SQL. The platform also supported internationalization with the translations managed on the i18nexus platform from which it fetches the newest translations whenever a server is started. For authentication, I integrated the system with the school’s existing authentication solution: an Active Directory server which used LDAP queries via the `activedirectory2` library. After authentication I persist the authenticated state along with some more user data in a secure cookie which expires after 24 hours. I chose the session-based authentication architecture over token-based as I only have one server and session-based was arguably more secure. The SMS delivery operates through GatewayAPI’s REST API with costs at around 3-7 cents (EUR) per message. The API permitted me to send, schedule and cancel scheduled messages and even fetch some analytics for the admin dashboard. One thing that took a long time was implementing all the error handling and the interactive UI on the new message page. Beyond type-validation, I validated phone numbers using another library prior to any API calls. I also had to handle all API potential error messages and translate them. Deploying to production was an invaluable learning experience—I self-hosted everything on a local PC, which taught me the foundations of networking and deployment methods. I used Docker Compose for multi-container orchestration, deploying PostgreSQL for the database layer and Nginx as a web server with SSL encryption via Let's Encrypt. I also set up dynamic DNS using No-IP to ensure consistent access despite a dynamic IP address and a redirection to forward network traffic from the router to the machine’s port where the application was running. I also automated database seeding with a retry mechanism that polls the database connection until it's ready. Please feel free to dive into the project and documentation below.

Technologies