Backend Services for a High-Volume Mobile Commerce Platform

Problem

Love's mobile application needed backend services and integrations to support features used by professional drivers, including a high-volume Showers experience. These were production services behind a live mobile app, so they had to work reliably for real users while integrating with several internal and third-party systems.

Constraints

The services supported production features that professional drivers depended on, so reliability mattered. They also had to integrate with several internal and third-party systems, including queue-management, retail POS, and payment-processing systems, and to do that without coupling the user-facing mobile features tightly to systems outside my control.

Architecture

I built and maintained Node.js APIs for the mobile application's features and used test-driven development to implement and validate service behavior. For asynchronous communication with internal and third-party systems, I developed Kafka producers and consumers, and I integrated the third-party queue-management, retail POS, and payment-processing systems the features depended on. I architected and implemented the backend functionality for the Showers feature, and I built Firebase-based push-notification capabilities used to communicate with mobile users.

Tradeoffs

Asynchronous, event-driven integration through Kafka trades the simplicity of direct synchronous calls for decoupling and resilience. Dependent systems process messages on their own schedule, which means the design has to account for eventual consistency and message handling rather than assuming an immediate reply. I favored that decoupling because the mobile features depended on several internal and third-party systems, and wiring them together synchronously would have made the platform only as available as its least reliable dependency.

Testing

I used test-driven development to implement and validate service behavior, writing tests with Mocha and Chai alongside the code so that each service was specified and checked as it was built rather than after the fact.

Results

• The Showers functionality processed more than $150k in daily transactions docs/profile/projects.md.
• Kafka integrations provided reliable communication between the mobile platform and dependent services docs/profile/projects.md.
• Push notifications produced a measurable increase in user engagement docs/profile/projects.md.

What I'd Change and What I Learned

Event-driven integration is powerful, but it is only as clear as its message contracts. What I carry forward is to document the schema and delivery expectations of each Kafka topic explicitly, so the boundaries between the mobile platform and the systems it depends on stay legible as the platform grows.