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besu/.env.database

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+# PostgreSQL Database Configuration for Besu Contracts
+
+# Database Connection
+DB_HOST=localhost
+DB_PORT=5432
+DB_NAME=besu_contracts
+DB_USER=besu_user
+DB_PASSWORD=besu_password
+
+# Full Connection URL
+DATABASE_URL=postgresql://besu_user:besu_password@localhost:5432/besu_contracts
+
+# PgAdmin Web Interface
+PGADMIN_URL=http://localhost:8080
+PGADMIN_EMAIL=admin@besu.local
+PGADMIN_PASSWORD=admin123
+
+# Besu Network Configuration
+BESU_RPC_URL=http://localhost:8545
+BESU_NETWORK_ID=1337
+
+# Database Schemas
+CONTRACTS_SCHEMA=contracts
+TRANSACTIONS_SCHEMA=transactions
+EVENTS_SCHEMA=events

besu/ARCHITECTURE.md

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+# Architecture Documentation
+
+## Overview
+
+This project implements a complete blockchain development environment using Hyperledger Besu with dual API implementations (Go and Node.js) and PostgreSQL integration.
+
+## System Architecture
+
+### High-Level Components
+
+```
+┌─────────────────────────────────────────────────────────────────┐
+│                    External Access Layer                        │
+├─────────────────────────────────────────────────────────────────┤
+│  Go REST API        │  Node.js API + Swagger UI                 │
+│  (Port 8080)        │  (Port 3001)                              │
+│                     │                                           │
+│  • Clean Arch       │  • Express.js                             │
+│  • Gin Framework    │  • Swagger Documentation                  │
+│  • Direct DB/BC     │  • Web3.js Integration                    │
+└─────────────────────────────────────────────────────────────────┘
+                              │
+┌─────────────────────────────────────────────────────────────────┐
+│                   Infrastructure Layer                          │
+├─────────────────────────────────────────────────────────────────┤
+│           Hyperledger Besu Network                              │
+│  ┌─────────┐ ┌─────────┐ ┌─────────┐ ┌─────────┐                │
+│  │ Node 0  │ │ Node 1  │ │ Node 2  │ │ Node 3  │                │
+│  │:8545    │ │:8546    │ │:8547    │ │:8548    │                │
+│  └─────────┘ └─────────┘ └─────────┘ └─────────┘                │
+│              QBFT Consensus Mechanism                           │
+└─────────────────────────────────────────────────────────────────┘
+                              │
+┌─────────────────────────────────────────────────────────────────┐
+│                     Data Layer                                  │
+├─────────────────────────────────────────────────────────────────┤
+│  PostgreSQL Database (Port 5432)                               │
+│  • Contract data persistence                                   │
+│  • Transaction history                                         │
+│  • Synchronization tracking                                    │
+│  • Health monitoring                                           │
+└─────────────────────────────────────────────────────────────────┘
+```
+
+## Detailed Component Analysis
+
+### 1. Hyperledger Besu Network
+
+**Purpose**: Private blockchain network with enterprise-grade features
+
+**Configuration**:
+- **Consensus**: QBFT (Quantum Byzantine Fault Tolerance)
+- **Nodes**: 4 validator nodes in private network
+- **Network ID**: 1337
+- **Genesis Block**: Pre-funded accounts with test ETH
+
+**Key Features**:
+- Immediate finality through QBFT consensus
+- Enterprise privacy features
+- EVM compatibility for Ethereum smart contracts
+- JSON-RPC API endpoints for each node
+
+**Network Topology**:
+```
+Node 0 (Bootnode) ←→ Node 1
+     ↕                ↕
+Node 3 ←————————————→ Node 2
+```
+
+### 2. Smart Contract Layer
+
+**Contract**: SimpleStorage.sol
+- Stores a single integer value
+- Provides get/set functionality
+- Emits events for value changes
+- Deployed address: `0x42699A7612A82f1d9C36148af9C77354759b210b`
+
+### 3. Go API Implementation
+
+**Architecture Pattern**: Clean Architecture
+
+```
+┌─────────────────┐
+│   HTTP Layer    │  ← Gin framework, routes, middleware
+├─────────────────┤
+│  Handler Layer  │  ← Request/response handling
+├─────────────────┤
+│ Business Logic  │  ← Core application logic
+├─────────────────┤
+│ Infrastructure  │  ← Database, blockchain clients
+└─────────────────┘
+```
+
+**Package Structure**:
+- `internal/handlers/`: HTTP request handlers
+- `internal/database/`: PostgreSQL operations
+- `internal/blockchain/`: Ethereum client wrapper
+- `internal/models/`: Data structures
+
+**Key Design Decisions**:
+- Dependency injection for testability
+- Error handling with proper HTTP status codes
+- Environment-based configuration
+- Clean, comment-free code structure
+
+### 4. Node.js API Implementation
+
+**Architecture**: Express.js with service layer
+
+```
+┌─────────────────┐
+│   Routes        │  ← Express routes definition
+├─────────────────┤
+│   Services      │  ← Business logic layer
+├─────────────────┤
+│   Data Access   │  ← Database and blockchain
+└─────────────────┘
+```
+
+**Features**:
+- Swagger UI for API documentation
+- Web3.js for blockchain interaction
+- Sequelize ORM for database operations
+- Comprehensive error handling
+
+### 5. Database Design
+
+**PostgreSQL Schema**:
+
+```sql
+-- Contract values table
+CREATE TABLE contract_values (
+    id SERIAL PRIMARY KEY,
+    value INTEGER NOT NULL,
+    tx_hash VARCHAR(66),
+    block_number BIGINT,
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+);
+
+-- System metadata
+CREATE TABLE system_metadata (
+    key VARCHAR(255) PRIMARY KEY,
+    value TEXT,
+    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+);
+```
+
+## Data Flow Patterns
+
+### 1. SET Operation Flow
+
+```
+Client Request → API Validation → Blockchain Transaction → Database Update → Response
+    ↓              ↓                     ↓                      ↓            ↓
+  JSON          Validate            Smart Contract         Record TX      Success/Error
+  Payload       Input               Method Call            in DB          Message
+```
+
+### 2. GET Operation Flow
+
+```
+Client Request → Cache Check → Blockchain Query → Response
+    ↓              ↓              ↓                ↓
+  Request       Check DB       Call Contract    Return Value
+  Received      First          get() Method     + Metadata
+```
+
+### 3. SYNC Operation Flow
+
+```
+Client Request → Blockchain Query → Database Compare → Update DB → Response
+    ↓              ↓                    ↓               ↓          ↓
+  Manual         Get Current           Check           Sync       Status
+  Trigger        Contract Value        Differences     Data       Report
+```
+
+## Security Considerations
+
+### 1. Private Key Management
+- Environment variable storage
+- No hardcoded credentials
+- Separate keys for different operations
+
+### 2. Input Validation
+- JSON schema validation
+- Type checking
+- Range validation for numeric inputs
+
+### 3. Network Security
+- Private blockchain network
+- Docker network isolation
+- No external blockchain exposure
+
+### 4. Database Security
+- Parameterized queries
+- Connection pooling
+- Health check monitoring
+
+## Scalability Design
+
+### 1. Horizontal Scaling
+- Stateless API design
+- Database connection pooling
+- Load balancer ready
+
+### 2. Performance Optimization
+- Async/await patterns
+- Connection reuse
+- Efficient database queries
+
+### 3. Monitoring
+- Health check endpoints
+- System status monitoring
+- Error logging and tracking
+
+## Integration Patterns
+
+### 1. API-to-Blockchain
+- JSON-RPC calls to Besu nodes
+- Transaction signing and submission
+- Event monitoring capabilities
+
+### 2. API-to-Database
+- Connection pooling
+- Transaction management
+- Data synchronization
+
+### 3. Cross-API Communication
+- Shared database for state
+- Common data models
+- Consistent response formats
+
+## Deployment Strategy
+
+### 1. Development Environment
+- Docker Compose for local development
+- Hot reload for both APIs
+- Integrated logging
+
+### 2. Infrastructure as Code
+- Docker configurations
+- Environment variable management
+- Service dependencies
+
+### 3. Testing Strategy
+- Unit tests for business logic
+- Integration tests for API endpoints
+- End-to-end blockchain interaction tests
+
+## Technology Choices Rationale
+
+### 1. Hyperledger Besu
+- Enterprise-grade blockchain
+- QBFT consensus for finality
+- EVM compatibility
+- Strong security model
+
+### 2. Dual API Implementation
+- **Go**: Performance, clean architecture, strong typing
+- **Node.js**: Rapid development, rich ecosystem, Swagger integration
+
+### 3. PostgreSQL
+- ACID compliance
+- Rich data types
+- Excellent performance
+- Strong ecosystem support
+
+### 4. Docker
+- Environment consistency
+- Easy deployment
+- Service isolation
+- Development/production parity
+
+## Future Enhancement Opportunities
+
+### 1. Advanced Features
+- Multi-contract support
+- Event listening and webhooks
+- Advanced querying capabilities
+- Real-time updates via WebSockets
+
+### 2. Security Enhancements
+- JWT authentication
+- Rate limiting
+- API key management
+- Audit logging
+
+### 3. Monitoring and Observability
+- Metrics collection
+- Distributed tracing
+- Performance monitoring
+- Alert management
+
+### 4. Scalability Improvements
+- Microservices architecture
+- Message queues
+- Caching layers
+- Read replicas
+
+---
+
+This architecture provides a solid foundation for blockchain application development with clear separation of concerns, robust error handling, and scalable design patterns.