How UPAS Works (Offline-First)
Browser-based architecture with complete offline capability for field operations.
Offline-First Architecture
UPAS is architected from the ground up to function without internet connectivity. Unlike traditional cloud-first applications that fail when networks are unavailable, UPAS delivers full operational capability offline through browser-based progressive web app design, service worker caching, and local data persistence.
Core Architecture
Offline-First Design
Complete operational capability without internet connectivity. All procedures, guidance, and data stored locally in the browser.
Opportunistic Synchronisation
When connectivity becomes available, automatic background sync of updates, new procedures, and usage telemetry (with consent).
Local Data Persistence
Browser IndexedDB stores all procedure packs, user preferences, and interaction history. Data survives browser restarts and device reboots.
Privacy-Preserving Architecture
No mandatory cloud dependency. All processing occurs on-device. Optional sync only when explicitly enabled by user.
Progressive Web App (PWA)
Installable from browser without app store. Works across desktop, mobile, and tablet with consistent experience.
Technical Implementation
Service Worker Caching
All application code, procedures, and assets cached by service worker for instant offline access.
Implementation: Cache-first strategy with periodic background updates when online.
Conflict-Free Synchronisation
Updates from multiple devices merged automatically without data loss or manual conflict resolution.
Implementation: Conflict-free replicated data types (CRDTs) for procedure annotations and user preferences.
Provenance Preservation
Every procedure includes cryptographic hash verification ensuring content integrity offline.
Implementation: SHA-256 hashing with digital signatures for verified publisher content.
Resilient Update Distribution
Procedure pack updates distributed via delta sync minimising bandwidth and enabling updates on limited connectivity.
Implementation: Binary diff patching with fallback to full download if connection unstable.
Why Offline-First Matters
Humanitarian field operations occur in contexts where internet connectivity is unreliable, expensive, or unavailable. Traditional cloud-first applications fail catastrophically in these environments, creating unacceptable operational risk.
UPAS prioritises offline capability as the primary design constraint, not an afterthought. The result is a system that works reliably in crisis zones, remote locations, and degraded network conditions where failure is not an option.
When connectivity becomes available, UPAS synchronises updates in the background without disrupting the user experience or requiring manual intervention. This approach delivers the resilience required for high-consequence field operations.