# INVENTORY PRO FLOW
## Technical Architecture & API Documentation

**Version:** 1.0.0  
**Developed By:** Triangular Data Logic  
**Technology Partner:** Top Gun Applied Technology  

---

# TABLE OF CONTENTS

1. [System Architecture Overview](#system-architecture-overview)
2. [Technology Stack](#technology-stack)
3. [Database Schema](#database-schema)
4. [API Documentation](#api-documentation)
5. [Authentication & Security](#authentication-security)
6. [Integration Guide](#integration-guide)
7. [Deployment Guide](#deployment-guide)
8. [Performance & Scaling](#performance-scaling)
9. [Monitoring & Observability](#monitoring-observability)
10. [Disaster Recovery](#disaster-recovery)

---

# 1. SYSTEM ARCHITECTURE OVERVIEW

## 1.1 High-Level Architecture

```
┌─────────────────────────────────────────────────────────────────┐
│                        CLIENT LAYER                              │
├─────────────────────────────────────────────────────────────────┤
│  Web App (React)  │  iOS App (RN)  │  Android App (RN)  │  PWA  │
└──────────────────┬──────────────────────────────────────────────┘
                   │
┌──────────────────┴──────────────────────────────────────────────┐
│                     CDN / CLOUDFRONT                             │
│                  (Static Assets, API Acceleration)               │
└──────────────────┬──────────────────────────────────────────────┘
                   │
┌──────────────────┴──────────────────────────────────────────────┐
│                     API GATEWAY LAYER                            │
├─────────────────────────────────────────────────────────────────┤
│  ┌─────────────┐  ┌─────────────┐  ┌─────────────┐             │
│  │   REST API  │  │  GraphQL    │  │  WebSocket  │             │
│  │   Gateway   │  │   Gateway   │  │   Server    │             │
│  └─────────────┘  └─────────────┘  └─────────────┘             │
└──────────────────┬──────────────────────────────────────────────┘
                   │
┌──────────────────┴──────────────────────────────────────────────┐
│                   MICROSERVICES LAYER                            │
├─────────────────────────────────────────────────────────────────┤
│  ┌──────────────┐ ┌──────────────┐ ┌──────────────┐            │
│  │  Inventory   │ │    Sales     │ │  Compliance  │            │
│  │   Service    │ │   Service    │ │   Service    │            │
│  └──────────────┘ └──────────────┘ └──────────────┘            │
│  ┌──────────────┐ ┌──────────────┐ ┌──────────────┐            │
│  │   Analytics  │ │    User      │ │ Integration  │            │
│  │   Service    │ │  Management  │ │   Service    │            │
│  └──────────────┘ └──────────────┘ └──────────────┘            │
└──────────────────┬──────────────────────────────────────────────┘
                   │
┌──────────────────┴──────────────────────────────────────────────┐
│                      DATA LAYER                                  │
├─────────────────────────────────────────────────────────────────┤
│  ┌──────────────┐ ┌──────────────┐ ┌──────────────┐            │
│  │  PostgreSQL  │ │   MongoDB    │ │    Redis     │            │
│  │  (Primary)   │ │(Unstructured)│ │   (Cache)    │            │
│  └──────────────┘ └──────────────┘ └──────────────┘            │
│  ┌──────────────┐ ┌──────────────┐                             │
│  │ TimescaleDB  │ │Elasticsearch │                             │
│  │(Time-series) │ │   (Search)   │                             │
│  └──────────────┘ └──────────────┘                             │
└─────────────────────────────────────────────────────────────────┘
```

## 1.2 Service Architecture

### Inventory Service
**Responsibilities:**
- CRUD operations for inventory items
- Stock level tracking and updates
- Barcode/SKU management
- Multi-location inventory sync
- Batch operations for bulk updates

**Technology:** Node.js + Express + TypeScript  
**Database:** PostgreSQL (primary), Redis (cache)  
**Message Queue:** RabbitMQ for async operations  

### Sales Service
**Responsibilities:**
- Transaction processing
- Sales analytics and reporting
- Revenue tracking
- Integration with POS systems
- Real-time sales notifications

**Technology:** Node.js + Express + TypeScript  
**Database:** TimescaleDB (time-series data)  
**Streaming:** Apache Kafka for real-time events  

### Compliance Service
**Responsibilities:**
- ABC board reporting automation
- TTB compliance tracking
- Audit trail maintenance
- Regulatory alerts and notifications
- License expiration monitoring

**Technology:** Python + FastAPI  
**Database:** PostgreSQL + MongoDB  
**Scheduler:** Celery for periodic tasks  

### Analytics Service
**Responsibilities:**
- AI/ML forecasting models
- Demand prediction
- Anomaly detection (shrinkage, theft)
- Custom report generation
- Data visualization

**Technology:** Python + TensorFlow + Scikit-learn  
**Database:** PostgreSQL + TimescaleDB  
**Data Warehouse:** AWS Redshift / Google BigQuery  

---

# 2. TECHNOLOGY STACK

## 2.1 Frontend Technologies

### Web Application
```json
{
  "framework": "React 18.2.0",
  "language": "TypeScript 5.0",
  "state": "Redux Toolkit 1.9",
  "routing": "React Router 6.x",
  "ui": "Material-UI 5.x",
  "forms": "React Hook Form",
  "api": "Axios + React Query",
  "charts": "Recharts + D3.js",
  "testing": "Jest + React Testing Library"
}
```

### Mobile Application
```json
{
  "framework": "React Native 0.72",
  "language": "TypeScript",
  "navigation": "React Navigation 6.x",
  "state": "Redux Toolkit",
  "ui": "React Native Paper",
  "icons": "React Native Vector Icons",
  "camera": "React Native Camera",
  "storage": "AsyncStorage",
  "push": "Firebase Cloud Messaging"
}
```

## 2.2 Backend Technologies

### API Layer
```json
{
  "runtime": "Node.js 20 LTS",
  "framework": "Express 4.x",
  "language": "TypeScript 5.0",
  "graphql": "Apollo Server 4.x",
  "websocket": "Socket.io 4.x",
  "validation": "Joi",
  "documentation": "Swagger/OpenAPI 3.0",
  "testing": "Jest + Supertest"
}
```

### Microservices
```json
{
  "inventory": "Node.js + Express",
  "sales": "Node.js + Express",
  "compliance": "Python 3.11 + FastAPI",
  "analytics": "Python 3.11 + FastAPI",
  "ml_engine": "TensorFlow 2.x + PyTorch"
}
```

## 2.3 Data Infrastructure

### Databases
```json
{
  "primary": "PostgreSQL 14 + PostGIS",
  "timeseries": "TimescaleDB 2.x",
  "document": "MongoDB 6.x",
  "cache": "Redis 7.x Cluster",
  "search": "Elasticsearch 8.x"
}
```

### Message Brokers
```json
{
  "queue": "RabbitMQ 3.x",
  "streaming": "Apache Kafka 3.x",
  "pubsub": "Redis Pub/Sub"
}
```

## 2.4 DevOps & Infrastructure

### Containerization & Orchestration
```json
{
  "containers": "Docker 24.x",
  "orchestration": "Kubernetes 1.28",
  "service_mesh": "Istio",
  "ingress": "NGINX Ingress Controller"
}
```

### CI/CD Pipeline
```json
{
  "version_control": "GitHub",
  "ci": "GitHub Actions",
  "cd": "ArgoCD",
  "testing": "CircleCI",
  "artifact": "Docker Hub / AWS ECR"
}
```

### Cloud Infrastructure
```json
{
  "provider": "AWS (primary), Azure (backup)",
  "compute": "ECS Fargate + Lambda",
  "storage": "S3 + EBS + EFS",
  "cdn": "CloudFront",
  "dns": "Route 53",
  "monitoring": "CloudWatch + Datadog"
}
```

---

# 3. DATABASE SCHEMA

## 3.1 Core Tables

### users
```sql
CREATE TABLE users (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    email VARCHAR(255) UNIQUE NOT NULL,
    password_hash VARCHAR(255) NOT NULL,
    first_name VARCHAR(100) NOT NULL,
    last_name VARCHAR(100) NOT NULL,
    role VARCHAR(50) NOT NULL CHECK (role IN ('admin', 'manager', 'staff')),
    organization_id UUID REFERENCES organizations(id),
    phone VARCHAR(20),
    is_active BOOLEAN DEFAULT true,
    last_login TIMESTAMP,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    deleted_at TIMESTAMP
);

CREATE INDEX idx_users_email ON users(email);
CREATE INDEX idx_users_org ON users(organization_id);
```

### organizations
```sql
CREATE TABLE organizations (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    name VARCHAR(255) NOT NULL,
    business_type VARCHAR(100) CHECK (business_type IN ('bar', 'restaurant', 'distillery', 'liquor_store', 'distributor')),
    license_number VARCHAR(100),
    tax_id VARCHAR(50),
    address_line1 VARCHAR(255),
    address_line2 VARCHAR(255),
    city VARCHAR(100),
    state VARCHAR(50),
    zip VARCHAR(20),
    country VARCHAR(50) DEFAULT 'USA',
    phone VARCHAR(20),
    subscription_tier VARCHAR(50) DEFAULT 'starter',
    subscription_status VARCHAR(50) DEFAULT 'active',
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);
```

### locations
```sql
CREATE TABLE locations (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    organization_id UUID REFERENCES organizations(id) ON DELETE CASCADE,
    name VARCHAR(255) NOT NULL,
    address_line1 VARCHAR(255),
    address_line2 VARCHAR(255),
    city VARCHAR(100),
    state VARCHAR(50),
    zip VARCHAR(20),
    coordinates GEOGRAPHY(POINT, 4326),
    is_primary BOOLEAN DEFAULT false,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

CREATE INDEX idx_locations_org ON locations(organization_id);
CREATE INDEX idx_locations_coordinates ON locations USING GIST (coordinates);
```

### products
```sql
CREATE TABLE products (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    sku VARCHAR(100) UNIQUE NOT NULL,
    name VARCHAR(255) NOT NULL,
    category VARCHAR(100) NOT NULL,
    subcategory VARCHAR(100),
    brand VARCHAR(100),
    size_ml INTEGER,
    abv DECIMAL(5,2),
    cost DECIMAL(10,2),
    price DECIMAL(10,2),
    barcode VARCHAR(100),
    supplier_id UUID REFERENCES suppliers(id),
    image_url TEXT,
    description TEXT,
    is_active BOOLEAN DEFAULT true,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

CREATE INDEX idx_products_sku ON products(sku);
CREATE INDEX idx_products_category ON products(category);
CREATE INDEX idx_products_barcode ON products(barcode);
```

### inventory
```sql
CREATE TABLE inventory (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    product_id UUID REFERENCES products(id) ON DELETE CASCADE,
    location_id UUID REFERENCES locations(id) ON DELETE CASCADE,
    quantity INTEGER NOT NULL DEFAULT 0,
    par_level INTEGER DEFAULT 0,
    reorder_point INTEGER DEFAULT 0,
    last_count_date TIMESTAMP,
    last_count_by UUID REFERENCES users(id),
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    UNIQUE(product_id, location_id)
);

CREATE INDEX idx_inventory_product ON inventory(product_id);
CREATE INDEX idx_inventory_location ON inventory(location_id);
CREATE INDEX idx_inventory_low_stock ON inventory(quantity) WHERE quantity <= par_level;
```

### transactions
```sql
CREATE TABLE transactions (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    type VARCHAR(50) CHECK (type IN ('sale', 'purchase', 'transfer', 'adjustment', 'waste', 'comp')),
    product_id UUID REFERENCES products(id),
    location_id UUID REFERENCES locations(id),
    quantity INTEGER NOT NULL,
    unit_price DECIMAL(10,2),
    total_price DECIMAL(10,2),
    reference_id VARCHAR(100),
    notes TEXT,
    created_by UUID REFERENCES users(id),
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

CREATE INDEX idx_transactions_product ON transactions(product_id);
CREATE INDEX idx_transactions_location ON transactions(location_id);
CREATE INDEX idx_transactions_date ON transactions(created_at);
CREATE INDEX idx_transactions_type ON transactions(type);
```

### compliance_reports
```sql
CREATE TABLE compliance_reports (
    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
    organization_id UUID REFERENCES organizations(id),
    report_type VARCHAR(100) NOT NULL,
    period_start DATE NOT NULL,
    period_end DATE NOT NULL,
    status VARCHAR(50) DEFAULT 'pending',
    submitted_at TIMESTAMP,
    submitted_by UUID REFERENCES users(id),
    file_url TEXT,
    metadata JSONB,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

CREATE INDEX idx_compliance_org ON compliance_reports(organization_id);
CREATE INDEX idx_compliance_dates ON compliance_reports(period_start, period_end);
```

---

# 4. API DOCUMENTATION

## 4.1 Base URL

**Production:** `https://api.inventoryproflow.com/v1`  
**Staging:** `https://api-staging.inventoryproflow.com/v1`  
**Development:** `http://localhost:3000/api/v1`  

## 4.2 Authentication

### Obtain Access Token
```http
POST /auth/login
Content-Type: application/json

{
  "email": "user@example.com",
  "password": "securepassword123"
}
```

**Response:**
```json
{
  "success": true,
  "data": {
    "accessToken": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...",
    "refreshToken": "8f3ae836da744329a0c6e54d...",
    "expiresIn": 3600,
    "user": {
      "id": "123e4567-e89b-12d3-a456-426614174000",
      "email": "user@example.com",
      "firstName": "John",
      "lastName": "Doe",
      "role": "admin"
    }
  }
}
```

### Using Access Token
```http
GET /inventory/items
Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
```

## 4.3 Core Endpoints

### Inventory Management

#### List Inventory Items
```http
GET /inventory/items?locationId={uuid}&page=1&limit=50
Authorization: Bearer {token}
```

**Query Parameters:**
- `locationId` (optional): Filter by location
- `category` (optional): Filter by category
- `lowStock` (optional): Only show low stock items
- `page` (default: 1): Page number
- `limit` (default: 50): Items per page

**Response:**
```json
{
  "success": true,
  "data": {
    "items": [
      {
        "id": "product-uuid",
        "sku": "JW-BL-750",
        "name": "Johnnie Walker Black Label",
        "category": "Whiskey",
        "quantity": 48,
        "parLevel": 30,
        "cost": 45.99,
        "price": 125.00,
        "lastCountDate": "2024-12-10T15:30:00Z"
      }
    ],
    "pagination": {
      "page": 1,
      "limit": 50,
      "total": 2847,
      "pages": 57
    }
  }
}
```

#### Add Inventory Item
```http
POST /inventory/items
Authorization: Bearer {token}
Content-Type: application/json

{
  "productId": "product-uuid",
  "locationId": "location-uuid",
  "quantity": 50,
  "parLevel": 30,
  "reorderPoint": 20
}
```

#### Update Inventory Count
```http
PUT /inventory/items/{id}/count
Authorization: Bearer {token}
Content-Type: application/json

{
  "quantity": 45,
  "notes": "Physical count - Friday evening"
}
```

### Sales & Transactions

#### Record Sale
```http
POST /transactions/sales
Authorization: Bearer {token}
Content-Type: application/json

{
  "locationId": "location-uuid",
  "items": [
    {
      "productId": "product-uuid",
      "quantity": 2,
      "unitPrice": 12.50
    }
  ],
  "referenceId": "POS-12345",
  "timestamp": "2024-12-14T20:30:00Z"
}
```

#### Get Sales Analytics
```http
GET /analytics/sales?startDate=2024-12-01&endDate=2024-12-14&locationId={uuid}
Authorization: Bearer {token}
```

**Response:**
```json
{
  "success": true,
  "data": {
    "totalSales": 124580.50,
    "totalTransactions": 3421,
    "averageTransaction": 36.42,
    "topProducts": [
      {
        "productId": "uuid",
        "name": "Grey Goose Vodka",
        "quantity": 245,
        "revenue": 8750.00
      }
    ],
    "dailyBreakdown": [
      {
        "date": "2024-12-14",
        "sales": 9850.00,
        "transactions": 287
      }
    ]
  }
}
```

### Compliance Reporting

#### Generate ABC Report
```http
POST /compliance/reports/abc
Authorization: Bearer {token}
Content-Type: application/json

{
  "locationId": "location-uuid",
  "periodStart": "2024-11-01",
  "periodEnd": "2024-11-30",
  "reportType": "monthly"
}
```

#### Get Compliance Status
```http
GET /compliance/status?organizationId={uuid}
Authorization: Bearer {token}
```

### AI Analytics & Forecasting

#### Get Demand Forecast
```http
POST /analytics/forecast
Authorization: Bearer {token}
Content-Type: application/json

{
  "productId": "product-uuid",
  "locationId": "location-uuid",
  "forecastDays": 30
}
```

**Response:**
```json
{
  "success": true,
  "data": {
    "productId": "product-uuid",
    "forecast": [
      {
        "date": "2024-12-15",
        "predictedDemand": 12,
        "confidence": 0.94
      }
    ],
    "recommendedOrderQuantity": 180,
    "recommendedOrderDate": "2024-12-18"
  }
}
```

## 4.4 WebSocket Events

### Real-Time Inventory Updates

**Connect:**
```javascript
const socket = io('wss://api.inventoryproflow.com', {
  auth: { token: 'Bearer eyJ...' }
});
```

**Subscribe to Location:**
```javascript
socket.emit('subscribe', { locationId: 'location-uuid' });
```

**Receive Updates:**
```javascript
socket.on('inventory:updated', (data) => {
  console.log('Inventory changed:', data);
  // { productId, newQuantity, changedBy, timestamp }
});

socket.on('sales:new', (data) => {
  console.log('New sale:', data);
});

socket.on('alert:lowStock', (data) => {
  console.log('Low stock alert:', data);
});
```

## 4.5 Error Handling

### Error Response Format
```json
{
  "success": false,
  "error": {
    "code": "INVALID_CREDENTIALS",
    "message": "Email or password is incorrect",
    "details": [],
    "timestamp": "2024-12-14T20:30:00Z",
    "requestId": "req-12345"
  }
}
```

### Common Error Codes
- `400` - Bad Request (validation errors)
- `401` - Unauthorized (invalid/expired token)
- `403` - Forbidden (insufficient permissions)
- `404` - Not Found
- `409` - Conflict (duplicate resource)
- `429` - Too Many Requests (rate limit exceeded)
- `500` - Internal Server Error
- `503` - Service Unavailable

---

# 5. AUTHENTICATION & SECURITY

## 5.1 JWT Token Structure

```json
{
  "header": {
    "alg": "RS256",
    "typ": "JWT"
  },
  "payload": {
    "sub": "user-uuid",
    "email": "user@example.com",
    "role": "admin",
    "org": "organization-uuid",
    "iat": 1702579800,
    "exp": 1702583400
  }
}
```

## 5.2 OAuth 2.0 Scopes

- `inventory:read` - View inventory data
- `inventory:write` - Modify inventory
- `sales:read` - View sales data
- `sales:write` - Record transactions
- `compliance:read` - View compliance reports
- `compliance:write` - Submit compliance reports
- `analytics:read` - Access analytics
- `admin:all` - Full administrative access

## 5.3 Security Best Practices

### Password Requirements
- Minimum 12 characters
- At least 1 uppercase letter
- At least 1 lowercase letter
- At least 1 number
- At least 1 special character
- No common passwords (dictionary check)

### Rate Limiting
```
Authentication: 5 requests/minute
API Calls: 1000 requests/hour (Starter)
API Calls: 5000 requests/hour (Professional)
API Calls: Unlimited (Enterprise)
```

### IP Whitelisting
Enterprise customers can whitelist specific IP addresses/ranges.

---

# 6. INTEGRATION GUIDE

## 6.1 POS Integration

### Webhook Configuration
```json
{
  "webhookUrl": "https://your-pos.com/webhooks/inventory",
  "events": ["sale.created", "inventory.updated"],
  "secret": "whsec_..."
}
```

### Sample Webhook Payload
```json
{
  "event": "sale.created",
  "timestamp": "2024-12-14T20:30:00Z",
  "data": {
    "transactionId": "txn-12345",
    "locationId": "location-uuid",
    "items": [
      {
        "sku": "GG-VD-750",
        "quantity": 1,
        "price": 12.50
      }
    ]
  },
  "signature": "sha256=abc123..."
}
```

## 6.2 Barcode Scanner Integration

### Supported Formats
- UPC-A / UPC-E
- EAN-13 / EAN-8
- Code 128
- QR Code

### Mobile SDK
```javascript
import { BarcodeScanner } from '@inventoryproflow/mobile-sdk';

const scanner = new BarcodeScanner({
  apiKey: 'your-api-key',
  locationId: 'location-uuid'
});

scanner.scan().then(result => {
  console.log('Scanned:', result.sku);
  // Auto-lookup product and update inventory
});
```

---

# 7. DEPLOYMENT GUIDE

## 7.1 Environment Setup

### Required Environment Variables
```bash
# Application
NODE_ENV=production
PORT=3000
APP_URL=https://app.inventoryproflow.com

# Database
DB_HOST=postgres.example.com
DB_PORT=5432
DB_NAME=inventory_pro_flow
DB_USER=app_user
DB_PASSWORD=secure_password

# Redis
REDIS_URL=redis://redis.example.com:6379

# JWT
JWT_SECRET=your-256-bit-secret
JWT_EXPIRY=3600

# AWS
AWS_REGION=us-east-1
AWS_ACCESS_KEY_ID=AKIA...
AWS_SECRET_ACCESS_KEY=...
S3_BUCKET=inventory-pro-flow-prod

# External Services
STRIPE_SECRET_KEY=sk_live_...
SENDGRID_API_KEY=SG...
```

## 7.2 Docker Deployment

### docker-compose.yml
```yaml
version: '3.8'
services:
  web:
    image: triangulardatalogic/inventory-pro-flow:latest
    ports:
      - "80:3000"
    environment:
      - NODE_ENV=production
    depends_on:
      - postgres
      - redis

  postgres:
    image: postgres:14
    volumes:
      - postgres_data:/var/lib/postgresql/data
    environment:
      - POSTGRES_DB=inventory_pro_flow

  redis:
    image: redis:7-alpine
    volumes:
      - redis_data:/data

volumes:
  postgres_data:
  redis_data:
```

## 7.3 Kubernetes Deployment

### deployment.yaml
```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: inventory-pro-flow
  labels:
    app: inventory-pro-flow
spec:
  replicas: 3
  selector:
    matchLabels:
      app: inventory-pro-flow
  template:
    metadata:
      labels:
        app: inventory-pro-flow
    spec:
      containers:
      - name: api
        image: triangulardatalogic/inventory-pro-flow:latest
        ports:
        - containerPort: 3000
        env:
        - name: NODE_ENV
          value: "production"
        resources:
          requests:
            memory: "512Mi"
            cpu: "500m"
          limits:
            memory: "1Gi"
            cpu: "1000m"
```

---

# 8. PERFORMANCE & SCALING

## 8.1 Performance Metrics

### Target Metrics
- API Response Time: < 200ms (p95)
- Database Query Time: < 50ms (p95)
- Page Load Time: < 2s (First Contentful Paint)
- Mobile App Launch: < 1s

### Caching Strategy
```javascript
// Redis caching for frequently accessed data
const cacheKey = `inventory:location:${locationId}`;
const cached = await redis.get(cacheKey);

if (cached) {
  return JSON.parse(cached);
}

const data = await db.getInventory(locationId);
await redis.setex(cacheKey, 300, JSON.stringify(data)); // 5 min TTL
return data;
```

## 8.2 Horizontal Scaling

### Load Balancing
- Application Layer: AWS ALB with sticky sessions
- Database: PostgreSQL read replicas (3x)
- Cache: Redis Cluster (6 nodes)

### Auto-Scaling Policy
```yaml
minReplicas: 3
maxReplicas: 20
targetCPUUtilizationPercentage: 70
targetMemoryUtilizationPercentage: 80
```

---

# 9. MONITORING & OBSERVABILITY

## 9.1 Logging

### Structured Logging Format
```json
{
  "timestamp": "2024-12-14T20:30:00.123Z",
  "level": "info",
  "service": "inventory-service",
  "requestId": "req-12345",
  "userId": "user-uuid",
  "message": "Inventory updated",
  "metadata": {
    "productId": "product-uuid",
    "oldQuantity": 48,
    "newQuantity": 45
  }
}
```

### Log Aggregation
- ELK Stack (Elasticsearch, Logstash, Kibana)
- CloudWatch Logs
- Datadog Logs

## 9.2 Metrics & Dashboards

### Application Metrics
- Request rate (requests/second)
- Error rate (%)
- Response time (ms)
- Active users (concurrent)

### Business Metrics
- Daily Active Users (DAU)
- Monthly Recurring Revenue (MRR)
- Inventory count operations
- Sales transactions processed

### Infrastructure Metrics
- CPU utilization (%)
- Memory usage (%)
- Disk I/O (IOPS)
- Network throughput (Mbps)

## 9.3 Alerting

### Critical Alerts
- Service down (< 99% uptime)
- Error rate > 1%
- Response time > 500ms (p95)
- Database connections exhausted

### Warning Alerts
- Error rate > 0.5%
- Response time > 300ms (p95)
- Disk usage > 80%
- Memory usage > 85%

---

# 10. DISASTER RECOVERY

## 10.1 Backup Strategy

### Database Backups
- **Full backups:** Daily at 2 AM UTC
- **Incremental backups:** Every 6 hours
- **Retention:** 30 days (production), 7 days (staging)
- **Location:** AWS S3 with cross-region replication

### Application State
- Redis snapshots: Every hour
- File uploads: Synced to S3 in real-time
- Configuration: Versioned in Git

## 10.2 Recovery Procedures

### Recovery Time Objective (RTO)
- Critical services: 15 minutes
- Non-critical services: 1 hour

### Recovery Point Objective (RPO)
- Database: < 1 hour
- File uploads: < 5 minutes

### Disaster Recovery Plan
1. **Assessment:** Identify scope of failure
2. **Communication:** Alert team and customers
3. **Failover:** Switch to backup region (if needed)
4. **Restore:** Restore from latest backup
5. **Verify:** Test all critical functionality
6. **Monitor:** Enhanced monitoring for 24 hours

---

**END OF TECHNICAL DOCUMENTATION**

For additional support:
- **Technical Support:** support@inventoryproflow.com
- **API Documentation:** https://docs.inventoryproflow.com
- **Developer Portal:** https://developers.inventoryproflow.com
- **Status Page:** https://status.inventoryproflow.com

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