Failover PSP Routing

Intelligent payment provider failover ensures maximum payment success rates through automatic routing to backup providers.

Failover Strategy Overview

Transaction Request
       │
       ▼
┌────────────────────────┐
│   Primary PSP (Stripe)    │
│                          │
│   Success Rate: 95%       │
│   Response: 150ms         │
└───────────┬─────────────┘
              │
              ▼ (if failure)
┌────────────────────────┐
│   Backup PSP (Adyen)      │
│                          │
│   Success Rate: 92%       │
│   Response: 200ms         │
└───────────┬─────────────┘
              │
              ▼ (if failure)
┌────────────────────────┐
│  Tertiary PSP (PayPal)    │
│                          │
│   Success Rate: 88%       │
│   Response: 300ms         │
└────────────────────────┘

Failover Decision Matrix

Routing Factors

Factor	Weight	Description
Success Rate	40%	Historical transaction success
Response Time	25%	Average API response time
Cost	20%	Transaction processing fees
Geographic Fit	10%	Regional optimization
Feature Support	5%	Required feature availability

Dynamic Scoring Algorithm

function calculatePSPScore(psp: PSP, transaction: Transaction): number {
  const successScore = psp.successRate * 0.4;
  const speedScore = (1 - psp.avgResponseTime / maxResponseTime) * 0.25;
  const costScore = (1 - psp.transactionFee / maxFee) * 0.2;
  const geoScore = psp.getGeographicScore(transaction.region) * 0.1;
  const featureScore = psp.supportsFeatures(transaction.requirements) * 0.05;
  
  return successScore + speedScore + costScore + geoScore + featureScore;
}

Failure Detection

Failure Types

Soft Failures (Retry-able)

• Network timeouts
• Rate limiting (429)
• Temporary server errors (5xx)
• PSP maintenance windows
• Temporary account issues

Hard Failures (No Retry)

• Invalid API credentials (401)
• Insufficient funds (402)
• Card declined (402)
• Fraud detection blocks
• Permanent account suspension

Detection Mechanisms

• HTTP status code analysis
• Response time monitoring
• Error pattern recognition
• Health check failures

Intelligent Retry Logic

Exponential Backoff

class RetryStrategy {
  calculateDelay(attemptNumber: number): number {
    const baseDelay = 1000; // 1 second
    const maxDelay = 30000;  // 30 seconds
    const jitter = Math.random() * 0.1; // 10% jitter
    
    const delay = Math.min(
      baseDelay * Math.pow(2, attemptNumber), 
      maxDelay
    );
    
    return delay * (1 + jitter);
  }
}

Retry Limits

• Maximum 3 retries per PSP
• Total timeout of 30 seconds
• Immediate failover for hard failures
• Circuit breaker activation after 5 consecutive failures

Circuit Breaker Pattern

Circuit States

• Closed: Normal operation, requests pass through
• Open: PSP marked as failed, requests bypass
• Half-Open: Testing PSP recovery, limited requests

Circuit Breaker Configuration

circuit_breaker:
  failure_threshold: 5         # Failures to open circuit
  timeout: 60s                 # Time before half-open attempt
  success_threshold: 3         # Successes to close circuit
  window_size: 100             # Sliding window for failure counting

Real-Time Health Monitoring

Health Metrics

• Success rate (5-minute rolling average)
• Average response time
• Error distribution by type
• Throughput per second
• Queue depth and processing lag

Monitoring Dashboard

PSP Health Dashboard
┌─────────────────────────────────┐
│ PSP        Status   Success  AvgTime │
├─────────────────────────────────┤
│ Stripe     ✓ UP     95.2%    142ms  │
│ Adyen      ✓ UP     92.8%    198ms  │
│ PayPal     ⚠ SLOW   88.1%    485ms  │
│ Craftgate  ✗ DOWN   45.3%    timeout│
└─────────────────────────────────┘

Automated Recovery

Recovery Triggers

• Circuit breaker half-open state
• Gradual traffic increase to recovered PSP
• Automatic primary PSP restoration
• Load balancing adjustment

Recovery Process

1. Detection: Health checks detect PSP recovery
2. Validation: Small percentage of traffic routed for testing
3. Gradual Ramp: Incrementally increase traffic percentage
4. Full Recovery: PSP restored to full capacity

Geographic Failover

Regional PSP Mapping

regional_preferences:
  north_america:
    primary: [stripe, authorize_net]
    secondary: [braintree, square]
  europe:
    primary: [adyen, stripe]
    secondary: [checkout_com, klarna]
  asia_pacific:
    primary: [adyen, stripe]
    secondary: [regional_providers]
  mena:
    primary: [craftgate, adyen]
    secondary: [stripe, paypal]

Cross-Region Failover

• Automatic geographic expansion during outages
• Latency-aware routing decisions
• Compliance-aware regional restrictions
• Currency conversion handling

Configuration Management

Dynamic Configuration

• Real-time PSP priority updates
• Feature flag-controlled routing
• A/B testing for routing strategies
• Emergency routing overrides

Configuration Example

{
  "routing_strategy": "intelligent",
  "psp_priorities": {
    "default": ["stripe", "adyen", "paypal"],
    "high_risk": ["adyen", "stripe"],
    "low_cost": ["stripe", "craftgate", "paypal"]
  },
  "failover_settings": {
    "max_retries_per_psp": 3,
    "total_timeout_seconds": 30,
    "circuit_breaker_threshold": 5
  }
}

Performance Optimization

Caching Strategies

• PSP capability caching
• Health status caching
• Routing decision caching
• Configuration caching

Async Processing

• Non-blocking PSP selection
• Parallel health checks
• Background metric collection
• Asynchronous retry processing

Next Steps

• Learn about Campaign Engine
• Understand Entitlement System
• Explore Payment Methods