Live Demo & Production Showcase
Haziri Lagao Mobile & Webhook Architecture
Demonstration of offline QR scanning and instantaneous n8n parent SMS dispatch.
The Core Challenge & Bottleneck
Schools in emerging markets still rely on manual paper attendance registers. Teachers spend 20–30 minutes every morning taking attendance, paper records are frequently lost or falsified, and parents receive no timely confirmation when their child safely reaches school or goes missing. The challenge was building an ultra-fast, intuitive application that works offline on low-end Android devices while syncing securely to cloud databases and firing instant parent alerts.
Before vs. After: Operational Comparison Matrix
Direct benchmarks comparing the legacy manual process against the automated production architecture:
| Operational Metric | Legacy / Manual Bottleneck | Automated Production Mesh | Measured Lift |
|---|---|---|---|
| Morning Attendance Duration | 25 minutes per classroom | 45 seconds via QR scan | 97% Time Saved |
| Parent Absence Alert Time | Never / End of week calls | Instant (<60 seconds) | Immediate Child Safety |
| Data Entry Error Rate | 14% clerical inaccuracies | 0% (Digital timestamping) | 100% Data Integrity |
| Offline Reliability | System unusable without internet | 100% functional with auto-sync | Zero Downtime |
System Architecture & Data Flow Logic
Teacher Client: Marks attendance via QR scan or batch UI → Saved instantly to local SQLite database.
Cloud Sync: Background sync pushes records to Supabase PostgreSQL via row-level security (RLS).
Webhook Trigger: Attendance event triggers secure HMAC-signed webhook to n8n server.
Parent Alert Dispatch: n8n validates secret key → Formats localized message → Dispatches SMS/WhatsApp alert in <2 seconds.
Step-by-Step Engineering & Build Process
Multi-Platform Client Engineering: Built a sleek, responsive Flutter application for Android, iOS, Windows, and Web featuring mobile barcode/QR camera scanning, manual batch toggling, and biometric staff authentication.
Offline-First Local Synchronization: Implemented local SQLite storage so teachers can mark attendance without an internet connection, automatically batch-syncing to Supabase when connectivity resumes.
HMAC-Authenticated Webhook Gateway: Designed a hardened webhook security architecture using X-Webhook-Secret verification in n8n, preventing spoofed requests or unauthorized attendance entries.
Real-Time Parent Alert Pipeline: n8n workflow triggers instant automated SMS and WhatsApp messages to parents notifying them of exact arrival times and unexcused absences.
Administrative Reporting & PDF Generation: Built comprehensive monthly PDF and Excel export services for school administrators to audit attendance trends and generate government compliance reports.
Production Deliverables Handed Over
Tools, APIs & Technology Stack
Engineered using industry-standard enterprise frameworks, managed vector databases, and high-throughput telephony pipelines: