ProjectMiddleware is the backend engine of a small ecosystem of services and apps designed to work together. Each piece has a single responsibility and evolves independently.
Middleware Playground
A Kotlin Multiplatform client application for Android and iOS that provides a visual interface for creating, previewing, and managing mapped routes — all powered by ProjectMiddleware on the backend.
What it does
- Route management — browse and manage all your registered mapped routes
- Visual mapping editor — step-by-step interface for configuring transformations: field mapping, concatenation, and complex JSON reshaping
- Real-time preview — test mappings against live data before committing
- Integrated auth — handles login and JWT token management via the User Service
Tech stack
| Layer | Technology |
|---|---|
| Shared logic | Kotlin Multiplatform |
| Android UI | Jetpack Compose |
| iOS UI | SwiftUI |
| HTTP client | Ktor Client (multiplatform) |
| Local persistence | SQLDelight |
| Async | Kotlin Coroutines & Flow |
Architecture
Clean Architecture with SOLID principles throughout: separated domain, data, and presentation layers; event-based UI state management; Factory pattern for platform-specific implementations; and an Adapter pattern to share ViewModels between Android and iOS.
Middleware User Service
A dedicated Kotlin/Ktor authentication microservice that acts as the security layer for the entire ecosystem. By separating authentication into its own service, the main middleware can focus exclusively on API transformation.
What it handles
- User registration and login — complete auth flows with BCrypt password hashing
- JWT issuance and validation — stateless, secure token management
- Password policies — minimum length, special character requirements
- Input sanitization — protection against injection and abuse
- Token validation endpoint — called by ProjectMiddleware before processing secured requests
Tech stack
| Component | Technology |
|---|---|
| Runtime | Kotlin + Ktor |
| Database | MongoDB |
| Password hashing | BCrypt |
| Auth tokens | JWT |
| Async | Kotlin Coroutines & Flow |
How the pieces fit together
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Middleware Playground (Android / iOS)
│
│ registers routes, manages config
▼
ProjectMiddleware ──── validates tokens ────▶ Middleware User Service
│
│ calls external APIs, transforms responses
▼
Your custom JSON output
- The User Service issues a JWT when the user signs in via the Playground
- The Playground uses that token to authenticate with ProjectMiddleware
- ProjectMiddleware validates the token, then calls the external API and maps the response
- The Playground displays the transformed data
Repository links
| Project | Repository |
|---|---|
| ProjectMiddleware (this) | github.com/LeonardoBai12/ProjectMiddleware |
| Middleware Playground | github.com/LeonardoBai12/MiddlewarePlayground |
| Middleware User Service | github.com/LeonardoBai12/MIddlewareUserService |