OutSystems Architecture Patterns I Use on Every Project
After 8+ years designing enterprise platforms on OutSystems — from Riyad Capital's digital banking platform to Bentley Motors' global dealer systems — I've settled on a core set of architectural patterns that apply to nearly every project.
1. The Service-Abstraction Layer
The biggest mistake I see in OutSystems projects is coupling the UI directly to integration logic. Instead, I always introduce a Service Layer (a set of Service Actions) that sits between screens and the actual REST/SOAP integrations.
Screen → Service Action → Integration Action → External API
Why it matters: When FACEKI updates their SDK or HyperPay changes an endpoint, I only update the Integration Action — the screens are untouched. This saved us weeks during the Riyad Capital platform stabilization.
2. Module Dependency Direction
Always enforce a strict one-way dependency flow:
Foundation Modules → Core Modules → End-User Modules
Never let a Foundation module reference a Core module. It sounds obvious, but it becomes a real problem at scale when you have 50+ modules and complex teams.
3. Offline-First Mobile Architecture
For OutSystems mobile apps, assume the network is hostile. Structure data sync with:
- Local storage first — all operations write locally
- Sync queue — pending operations persisted in a client-side table
- Background sync — timer-based sync trigger, not on-demand
- Conflict resolution — server wins by default; document exceptions explicitly
This pattern handled everything we threw at it during the mobile rollout at Riyad Capital, including edge cases with intermittent 4G in elevator lobbies.
4. Centralised Error Handling
Create a single Error_Handler Service Action that:
- Logs to a central error table
- Sends an alert for P1 errors
- Returns a typed error result (never throws)
Every integration and business logic action calls it. Never scatter ExceptionHandler blocks across modules.
These four patterns alone have saved more debugging hours than I can count. Happy to go deeper on any of them — reach out via LinkedIn.