Architecture

BERT implements a sophisticated Layer 4 System Language architecture that bridges systems science theory with modern software engineering practices.

Architecture Overview

BERT uses a component-based ECS (Entity-Component-System) architecture built on the Bevy game engine, with a reactive web UI layer powered by Leptos. This creates a powerful combination of real-time visualization and intuitive user interaction.

Technology Stack

┌─────────────────────────────────────────────────┐
│ User Interface Layer (Leptos Web Components)    │
│ - Property editing panels                       │
│ - System hierarchy navigation                   │
│ - Interactive controls and forms               │
├─────────────────────────────────────────────────┤
│ Visualization Layer (Bevy Game Engine)          │
│ - Entity-Component-System architecture         │
│ - Real-time rendering and interaction          │
│ - Infinite nesting with automatic scaling      │
├─────────────────────────────────────────────────┤
│ System Model Layer (Component Definitions)      │
│ - System elements and relationships            │
│ - Interaction lifecycle management             │
│ - Event-driven state coordination              │
├─────────────────────────────────────────────────┤
│ Data Model Layer (Persistence & Serialization)  │
│ - JSON-based save/load system                  │
│ - Version management and compatibility         │
│ - Comprehensive data validation                │
├─────────────────────────────────────────────────┤
│ Platform Layer (Tauri Desktop Framework)        │
│ - Cross-platform deployment                    │
│ - Native OS integration                        │
│ - File system and window management            │
└─────────────────────────────────────────────────┘

Core Technologies

• Rust: Systems programming language for performance and safety

• Bevy: Entity-Component-System game engine for visualization

• Leptos: Reactive web framework for UI components

• Tauri: Desktop application framework for cross-platform deployment

• JSON: Human-readable serialization format for data persistence

System Language Implementation

BERT implements the complete System Language framework through a five-layer architecture:

Layer 5: Application Framework

• BERT Application

• Tauri Desktop Integration

• Cross-Platform Deployment

Layer 4: Implementation Languages

• Visual Representation

• Interactive UI Components

• Event-Driven Coordination

Layer 3: Knowledge Representation

• Data Model & Serialization

• Persistence Layer

• Version Management

Layer 2: Formal Specification

• Component Definitions

• Entity Relationships

• System Constraints

Layer 1: Theoretical Framework

• Systems Science Concepts

• Mathematical Foundations

• Conceptual Integrity

Core Subsystems

1. Interaction System

Purpose: Manages the complete lifecycle of connections between system entities

Key Features:

• 4-stage lifecycle: Created → Interface → Other End → Complete

• Component-based state machine: Dynamic component addition/removal

• Context-aware behavior: Different workflows for root vs. subsystem contexts

• Automatic state recovery: Handles entity removal and state reversion

Components:

// Connection tracking
FlowStartConnection, FlowEndConnection
FlowStartInterfaceConnection, FlowEndInterfaceConnection

// UI state management  
HasFlowInterfaceButton, HasFlowOtherEndButton

// Permanent components
Flow, FlowCurve

2. Visual System

Purpose: Provides sophisticated hierarchical rendering with infinite nesting support

Key Features:

• Scene graph hierarchy: Parent-child entity relationships

• Dynamic scaling: Zoom and nesting-level aware scaling

• Z-coordinate system: Proper draw order for infinite nesting

• Automatic curve generation: Cubic Bézier curves with computed control points

• Context-aware rotation: Aesthetic entity positioning

Components:

// Spatial organization
InitialPosition, NestingLevel

// Visual representation
FlowCurve, Transform

// Global state
ZoomLevel (Resource)

3. Plugin Architecture

Purpose: Modular system integration with coordinated lifecycle management

Current Plugins:

• Mouse Interaction: Selection, dragging, and interaction handling

• Label System: Text labeling with entity composition

• Lyon Selection: Advanced selection and highlighting

Plugin Structure:

src/bevy_app/plugins/
├── mod.rs                  # Plugin coordination
├── mouse_interaction/      # Mouse and selection handling
├── label/                  # Text labeling system
└── lyon_selection/         # Advanced selection graphics

4. Data Model and Persistence

Purpose: Comprehensive data representation and persistence with version management

Key Features:

• Hierarchical data model: Reflects system nesting structure

• JSON serialization: Human-readable and version-controllable

• Backward compatibility: Handles format evolution

• Comprehensive validation: Data integrity and constraint checking

Implementation:

src/bevy_app/data_model/
├── mod.rs                  # Core data structures and traits
├── save.rs                 # Serialization logic
└── load.rs                 # Deserialization and validation

5. Event System and Coordination

Purpose: Cross-system communication and state synchronization

Event Categories:

• UI Events: User interactions from Leptos components

• System Events: Entity creation, modification, removal

• Lifecycle Events: Interaction state transitions

• Focus Events: Entity selection and UI state changes

Integration Pattern:

// Event flow: Leptos UI → Events → Bevy Systems → State Updates → Rendering
src/events.rs               # Cross-system event definitions

Systems Science Mapping

The architecture directly implements core systems science concepts:

Systems Concept	Implementation	Location
System	SystemComponent with boundaries	components/system_elements.rs
Subsystem	Nested SubsystemComponent	components/system_elements.rs
Flow	FlowComponent with lifecycle	components/connections.rs
Interface	InterfaceComponent with positioning	components/connections.rs
External Entity	ExternalEntityComponent	components/system_elements.rs
Hierarchy	Scene graph with infinite nesting	Visual system architecture
Boundaries	Visual containers with permeability	Bundle spawn system

Integration Patterns

Leptos-Bevy Communication

Challenge: Integrate web-based UI with game engine visualization

Solution: Event-driven architecture with shared state management

Flow:

1. Leptos UI captures user interaction

2. Event System triggers appropriate events

3. Bevy Systems respond to events

4. Component State updates

5. Rendering reflects changes

6. UI receives state feedback

Component Lifecycle Management

Pattern: Dynamic component addition/removal based on entity state

Implementation: Specialized systems for each lifecycle stage

Benefits: Clean state management and automatic cleanup

Cross-System Data Flow

Principle: Unidirectional data flow with event-driven updates

Implementation: Events trigger system updates, systems modify components, rendering reflects changes

Benefits: Predictable state management and debugging

Performance Architecture

Rendering Performance

Target: 60+ FPS with complex system models

Strategies:

• Efficient ECS queries: Optimized component access patterns

• Batched updates: Minimize individual entity operations

• LOD system: Level-of-detail for complex visualizations

• Culling: Z-coordinate based rendering optimization

Memory Management

Approach: Rust's ownership system for memory safety

Optimization:

• Component pooling: Reuse components when possible

• Efficient data structures: Minimize allocation overhead

• Lazy evaluation: Compute only when necessary

Scalability Considerations

• Infinite Nesting: Hierarchical algorithms that scale with depth

• Large Models: Efficient handling of complex system representations

• Real-time Interaction: Responsive UI even with large datasets

Development Standards

Documentation Requirements

Requirement: 100% compliance with professional documentation templates

Implementation:

• 6 comprehensive templates for all code element types

• Complete function documentation with Parameters, Returns, Errors, Panics

• Systems science context for all architectural decisions

Code Quality Standards

Requirements:

• No clippy warnings: All code passes strict linting

• Comprehensive testing: Unit, integration, and systems tests

• Performance targets: 60+ FPS maintained in visualization

• Architecture compliance: Follows established patterns

Extension Points

Adding New System Elements

Process:

1. Component Definition: Add to system_elements.rs

2. Visual Representation: Create spawn bundle

3. UI Integration: Add Leptos editing components

4. Serialization: Update data model

5. Documentation: Complete template compliance

Plugin Development

Framework: Bevy plugin system with coordinated lifecycle

Integration: Event system for cross-plugin communication

Standards: Follow established plugin patterns

Visual System Extensions

• Rendering: Custom shaders and visual effects

• Interaction: New interaction patterns and behaviors

• Scaling: Enhanced scaling and visibility algorithms

Current Implementation Status

Fully Implemented Systems

✅ Core Architecture: Complete ECS foundation with Bevy ✅ Interaction Lifecycle: 4-stage state machine fully implemented ✅ Visual System: Infinite nesting with automatic scaling ✅ Data Model: Comprehensive persistence with version management ✅ Plugin System: Mouse interaction, labeling, selection ✅ Documentation: Professional standards with template compliance

Areas for Enhancement

🔄 Bundle System: Needs comprehensive documentation 🔄 Event System: Requires detailed architectural documentation 🔄 Resource Management: Global state patterns need documentation 🔄 Performance Optimization: Systematic optimization documentation

Future Architecture Evolution

Planned Enhancements

1. Complete SysXML Support: Generate XML representations of systems

2. Transformation Rules: Add computational capabilities for system simulation

3. Memory/History: Track system state changes over time

4. Time Interval Handling: Support multi-scale modeling

5. Knowledge Base Integration: Connect with external systems databases

Architectural Principles for Evolution

1. Maintain Conceptual Integrity: All changes align with systems science theory

2. Preserve Performance: 60+ FPS target maintained

3. Extend Documentation: 100% compliance for all new code

4. Follow Established Patterns: Use proven architectural approaches

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For detailed technical specifications, see the comprehensive architecture documentation in the project repository at docs/architecture/comprehensive-architecture-overview.md.