Architectural Overview¶

Project Vision¶

R Commerce is a lightweight, high-performance headless ecommerce platform built entirely in Rust. It provides a complete API-first solution for businesses that need a fast, reliable, and self-contained ecommerce backend without the bloat of traditional monolithic platforms.

Why Rust?¶

Performance & Resource Efficiency¶

Memory Safety Without Garbage Collection: Rust's ownership model eliminates runtime garbage collection pauses, providing consistent low-latency performance critical for ecommerce transactions
Zero-Cost Abstractions: High-level features compile down to efficient machine code, ensuring excellent performance without sacrificing developer experience
Predictable Resource Usage: Single-digit millisecond response times with minimal memory footprint (typically 10-50MB per instance vs 500MB-2GB for JVM/Node alternatives)

Reliability & Safety¶

Compile-Time Guarantees: Prevent entire classes of bugs (null pointer dereferences, buffer overflows, data races) before code reaches production
Type System: Strong static typing catches errors early, reducing runtime failures during critical payment operations
Fearless Concurrency: Leverage multi-core processors safely for high-throughput order processing and API handling

Operational Benefits¶

Single Binary Deployment: Compile to a single executable (~20MB) - no runtime dependencies, container-friendly
Predictable Performance: Consistent CPU/memory usage patterns simplify capacity planning and autoscaling
Long-Term Maintenance: Rust's stability guarantees and backward compatibility reduce technical debt accumulation

Why Headless?¶

Architectural Advantages¶

Frontend Agnostic - Use any frontend technology (React, Vue, mobile apps, IoT devices) without backend constraints
Microservices Ready - Integrate with existing systems or scale components independently
API-First Design - Every feature is accessible programmatically, enabling automation and integration
Reduced Attack Surface - No admin UI means fewer attack vectors; security through simplicity
Multi-Channel Commerce - Single backend powers web, mobile, POS, marketplaces simultaneously

Total Cost of Ownership¶

While headless requires frontend development, it reduces: - Hosting costs (lighter backend) - Maintenance overhead (less code to maintain) - Security incidents (smaller attack surface) - Upgrade complexity (no UI migrations)

Core Design Principles¶

1. Modularity Over Monolith¶

Plugin-based architecture for payments, shipping, and notifications
Feature flags to enable/disable functionality
Stratified design: Core → Services → API → Plugins

2. Configuration as Code¶

All configuration via TOML/JSON files or environment variables
No database configuration tables (except dynamic business data)
Version-controlled configuration enables GitOps workflows

3. API Completeness¶

100% of functionality exposed via REST APIs
No hidden admin-only features
Comprehensive webhooks for external integration

4. PostgreSQL Optimized¶

Designed for PostgreSQL 14+ with advanced features
Migration system for schema management
Performance optimized queries

5. Observability Built-In¶

Structured logging (JSON format)
Prometheus metrics endpoints
Distributed tracing support
Health check endpoints

High-Level Architecture¶

┌─────────────────────────────────────────────────────────────┐
│                        API Layer                             │
│  (REST - Axum/Tokio)                                        │
└──────────────────────────┬──────────────────────────────────┘
                           │
┌──────────────────────────▼──────────────────────────────────┐
│                    Service Layer                             │
│  OrderService, ProductService, PaymentService, etc         │
└──────────────────────────┬──────────────────────────────────┘
                           │
┌──────────────────────────▼──────────────────────────────────┐
│                   Core Domain Layer                          │
│  Entities, Value Objects, Business Logic                   │
└──────────────────────────┬──────────────────────────────────┘
                           │
┌──────────────────────────▼──────────────────────────────────┐
│                Data Access Layer                             │
│  Repository Pattern, PostgreSQL                            │
└──────────────────────────┬──────────────────────────────────┘
                           │
┌──────────────────────────▼──────────────────────────────────┐
│              Database/External Services                      │
│  PostgreSQL, Redis, Payment Gateways, Shipping APIs        │
└─────────────────────────────────────────────────────────────┘

Key Components¶

API Gateway (Axum)¶

HTTP request routing and validation
Authentication/authorization middleware
Rate limiting and request logging
CORS and security headers
WebSocket support for real-time updates

Core Services¶

Order Management: Lifecycle, status transitions, fraud detection
Product Catalog: Categories, variants, inventory management
Customer Management: Profiles, addresses, order history
Payment Processing: Multi-gateway orchestration
Shipping Integration: Label generation, tracking
Webhook Dispatcher: Event-driven notifications

Plugin System¶

Dynamic loading of payment/shipping providers
Trait-based interface for extensibility
Configuration-driven provider selection
Sandboxed execution environment

Background Workers¶

Async task processing using Tokio
Order fulfillment automation
Payment status synchronization
Email notification sending
Inventory synchronization

Performance Targets¶

Metric	Target
API Response Time	P50 < 10ms, P99 < 50ms
Throughput	> 10,000 requests/second on 4-core VM
Memory Usage	< 50MB per instance at rest
Startup Time	< 1 second
Order Processing	> 1,000 orders/second sustained

Deployment Characteristics¶

Single Binary: ~20MB executable
Container Image: ~50MB (alpine-based)
Configuration: Single TOML file + environment variables
Horizontal Scaling: Stateless design, scale via load balancers
High Availability: Multi-instance deployment with shared database

Comparison with Alternatives¶

Feature	R Commerce	WooCommerce	Shopify (Headless)	Medusa
Language	Rust	PHP	Ruby/Node	Node.js
Performance	Excellent	Moderate	Good	Good
Self-Hosted	Yes	Yes	No	Yes
Resource Usage	Very Low	High	N/A	Moderate
Complexity	Low	High (with plugins)	Medium	Medium
API Completeness	100%	Partial	100%	100%

Project Structure¶

crates/
├── rcommerce-core/     # Core library - models, traits, config, repositories
├── rcommerce-api/      # HTTP API server (Axum)
└── rcommerce-cli/      # Command-line management tool

Core Modules¶

Models: Product, Customer, Order, Address, Payment, API Keys, etc.
Config: Multi-format configuration (TOML, env vars)
Traits: Repository pattern, plugin architecture
Repositories: PostgreSQL repository implementations
Error Handling: Comprehensive error types with HTTP mapping
WebSocket: Real-time updates and notifications
Cache: Redis and in-memory caching support

Next Steps¶

Continue reading: - Data Model - Core entities and relationships - Database Abstraction - Repository pattern and data access - Order Management - Order lifecycle and fulfillment - Notifications - Email and webhook system - Media Storage - File upload and storage backends