API Connector Service

API Connector Service

Executive Summary

Background & Motivation

Problem Statement

• Duplicated Authentication Logic: Each service reimplements OAuth, API key management, and token refresh
• Inconsistent Error Handling: Different approaches to retry logic, timeout handling, and error recovery
• Security Vulnerabilities: API keys scattered across services without centralized management
• Monitoring Gaps: No unified visibility into API performance, usage, and costs
• Rate Limit Issues: Uncoordinated requests leading to API throttling and service degradation

Why This Solution

• Centralized Security: Single point of authentication and credential management across all API types
• Unified Interface: Consistent API for all external service interactions (AI models, data stores, web crawlers, integrations)
• Intelligent Routing: Load balancing, failover, and provider selection optimization across diverse API categories
• Performance Monitoring: Real-time metrics, usage tracking, and cost management for all connected services
• Enterprise Features: Rate limiting, caching, audit logging, and compliance support for comprehensive API governance

Goals & Non-Goals

Goals

1. Secure API Management: Centralized authentication and credential handling
2. Connection Monitoring: Real-time health checks and performance tracking
3. Intelligent Routing: Provider selection based on availability and performance
4. Error Recovery: Robust retry logic and failover mechanisms
5. Performance Optimization: Caching, compression, and connection pooling
6. Usage Analytics: Detailed metrics for cost optimization and planning
7. Developer Experience: Simple, consistent API for service integration

Non-Goals

1. Model Training: Focus on inference APIs, not training workflows
2. Complex AI Logic: Pure connector service, not AI processing logic
3. UI Components: Backend service only, no user interface elements
4. Data Processing: Request/response transformation handled by calling services

Technical Design

High-Level Architecture

Core Components

1. Connection Manager

• HTTP/2 connection pooling with keep-alive
• Configurable connection limits per provider
• Automatic connection cleanup and lifecycle management
• SSL/TLS certificate validation and pinning

2. Authentication Manager

• API key management with rotation support
• OAuth 2.0 flow handling for supported providers
• Bearer token caching and refresh logic
• Secure credential storage integration

3. Connection Monitor

• Continuous health checks with configurable intervals
• Response time and error rate tracking
• Provider availability scoring
• Real-time alerting for service degradation

4. Request Router

• Load balancing across multiple provider instances
• Automatic failover to backup providers
• Performance-based routing decisions
• Provider capability matching

5. Error Handler

• Exponential backoff retry logic
• Circuit breaker pattern implementation
• Error categorization and handling strategies
• Dead letter queue for failed requests

API Specifications

Primary Interfaces

interface ApiConnectorConfig {
  providers: ProviderConfig[];
  authentication: AuthConfig;
  monitoring: MonitoringConfig;
  retry: RetryConfig;
  caching: CacheConfig;
}

interface ProviderConfig {
  name: string;
  baseUrl: string;
  apiKey?: string;
  authType: 'api_key' | 'oauth2' | 'bearer' | 'custom';
  rateLimit: {
    requestsPerMinute: number;
    requestsPerHour: number;
    tokensPerMinute?: number;
  };
  timeout: number;
  priority: number; // Higher = preferred
  capabilities: ModelCapability[];
}

interface AuthConfig {
  credentialStore: 'env' | 'vault' | 'aws_secrets' | 'azure_keyvault';
  tokenCache: boolean;
  refreshInterval: number; // minutes
}

interface MonitoringConfig {
  healthCheckInterval: number; // seconds
  metricsEnabled: boolean;
  alerting: {
    errorRateThreshold: number;
    responseTimeThreshold: number;
    webhookUrl?: string;
  };
}

interface ConnectionHealthStatus {
  provider: string;
  isHealthy: boolean;
  responseTime: number;
  errorRate: number;
  lastChecked: Date;
  consecutiveFailures: number;
}

interface ApiRequest {
  provider?: string; // Optional: let router decide
  endpoint: string;
  method: 'GET' | 'POST' | 'PUT' | 'DELETE';
  headers?: Record<string, string>;
  body?: any;
  timeout?: number;
  retries?: number;
  priority?: 'low' | 'normal' | 'high';
  cacheKey?: string;
  cacheTTL?: number;
}

interface ApiResponse<T = any> {
  success: boolean;
  data?: T;
  error?: {
    code: string;
    message: string;
    provider: string;
    retryable: boolean;
    details?: any;
  };
  metadata: {
    provider: string;
    responseTime: number;
    cached: boolean;
    requestId: string;
    tokensUsed?: number;
    cost?: number;
  };
}

// Main service interface
interface ApiConnectorService {
  // Connection management
  initializeConnections(config: ApiConnectorConfig): Promise<void>;
  checkConnectionHealth(provider?: string): Promise<ConnectionHealthStatus[]>;
  refreshConnections(): Promise<void>;
  
  // Request handling
  makeRequest<T>(request: ApiRequest): Promise<ApiResponse<T>>;
  makeStreamingRequest(request: ApiRequest): AsyncIterableIterator<ApiResponse>;
  
  // Provider management
  addProvider(config: ProviderConfig): Promise<void>;
  removeProvider(name: string): Promise<void>;
  listProviders(): ProviderInfo[];
  
  // Monitoring and analytics
  getMetrics(timeRange?: TimeRange): Promise<ApiMetrics>;
  getUsageStats(provider?: string): Promise<UsageStats>;
  
  // Cache management
  clearCache(pattern?: string): Promise<void>;
  getCacheStats(): Promise<CacheStats>;
}

Connection Checker Implementation

class ConnectionChecker {
  private healthCache: Map<string, ConnectionHealthStatus> = new Map();
  private checkInterval: NodeJS.Timer;

  constructor(private config: MonitoringConfig) {
    this.startContinuousChecking();
  }

  public async checkConnection(provider: string): Promise<ConnectionHealthStatus> {
    const startTime = Date.now();
    
    try {
      // Perform actual health check request
      const response = await this.performHealthCheck(provider);
      const responseTime = Date.now() - startTime;
      
      const status: ConnectionHealthStatus = {
        provider,
        isHealthy: response.ok,
        responseTime,
        errorRate: this.calculateErrorRate(provider),
        lastChecked: new Date(),
        consecutiveFailures: response.ok ? 0 : this.incrementFailureCount(provider)
      };

      this.healthCache.set(provider, status);
      
      // Trigger alerts if needed
      if (!status.isHealthy) {
        await this.triggerAlert(status);
      }

      return status;
    } catch (error) {
      const status: ConnectionHealthStatus = {
        provider,
        isHealthy: false,
        responseTime: Date.now() - startTime,
        errorRate: 1.0,
        lastChecked: new Date(),
        consecutiveFailures: this.incrementFailureCount(provider)
      };

      this.healthCache.set(provider, status);
      await this.triggerAlert(status);
      
      return status;
    }
  }

  private async performHealthCheck(provider: string): Promise<Response> {
    const providerConfig = this.getProviderConfig(provider);
    
    // Simple health check - ping endpoint or lightweight request
    const healthEndpoint = providerConfig.healthCheckEndpoint || 
      `${providerConfig.baseUrl}/health`;
    
    return fetch(healthEndpoint, {
      method: 'GET',
      timeout: this.config.healthCheckTimeout || 5000,
      headers: {
        'User-Agent': 'Augment-It-Health-Check/1.0',
        ...(providerConfig.healthCheckHeaders || {})
      }
    });
  }

  private startContinuousChecking(): void {
    this.checkInterval = setInterval(async () => {
      const providers = this.getConfiguredProviders();
      
      const checks = providers.map(provider => 
        this.checkConnection(provider.name)
      );
      
      await Promise.allSettled(checks);
    }, this.config.healthCheckInterval * 1000);
  }

  public getConnectionStatus(provider?: string): ConnectionHealthStatus[] {
    if (provider) {
      const status = this.healthCache.get(provider);
      return status ? [status] : [];
    }
    
    return Array.from(this.healthCache.values());
  }

  public async triggerAlert(status: ConnectionHealthStatus): Promise<void> {
    if (status.consecutiveFailures >= this.config.alerting.failureThreshold) {
      const alert = {
        type: 'CONNECTION_FAILURE',
        provider: status.provider,
        consecutiveFailures: status.consecutiveFailures,
        errorRate: status.errorRate,
        timestamp: new Date().toISOString()
      };

      // Send to webhook if configured
      if (this.config.alerting.webhookUrl) {
        await this.sendWebhookAlert(alert);
      }

      // Log critical alert
      console.error(`CRITICAL: Provider ${status.provider} has failed ${status.consecutiveFailures} consecutive health checks`);
    }
  }

  private async sendWebhookAlert(alert: any): Promise<void> {
    try {
      await fetch(this.config.alerting.webhookUrl, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(alert)
      });
    } catch (error) {
      console.error('Failed to send webhook alert:', error);
    }
  }
}

Integration with Request Validator

// Integration pattern
class ApiConnectorService {
  constructor(
    private config: ApiConnectorConfig,
    private requestValidator: ApiRequestValidator
  ) {
    // ... initialization
  }

  async makeRequest<T>(request: ApiRequest): Promise<ApiResponse<T>> {
    // Validate request before processing
    const validationResult = await this.requestValidator.validateRequest(request);
    if (!validationResult.isValid) {
      return {
        success: false,
        error: {
          code: 'VALIDATION_ERROR',
          message: validationResult.errors.join(', '),
          provider: 'validator',
          retryable: false,
          details: validationResult.errors
        },
        metadata: {
          provider: 'validator',
          responseTime: 0,
          cached: false,
          requestId: this.generateRequestId()
        }
      };
    }

    // Proceed with validated request
    return this.executeRequest(request);
  }
}

Error Handling & Recovery

Expected Error Scenarios

1. Network Connectivity Issues
   • Connection timeouts
   • DNS resolution failures
   • SSL certificate errors
   • Network partitions
2. Authentication Failures
   • Invalid API keys
   • Expired tokens
   • Rate limit exceeded
   • Insufficient permissions
3. Provider-Specific Errors
   • Service unavailable (503)
   • Rate limiting (429)
   • Invalid request format
   • Model capacity limits
4. Circuit Breaker Activation
   • Consecutive failure threshold reached
   • Provider marked as unhealthy
   • Automatic failover triggered

Recovery Strategies

• Exponential Backoff: Progressive delay increases for retries
• Circuit Breaker Pattern: Fail fast when provider is degraded
• Automatic Failover: Route to backup providers when primary fails
• Graceful Degradation: Return cached responses when possible
• Dead Letter Queue: Persist failed requests for manual review

Security Considerations

1. Credential Management
   • Never log API keys or sensitive tokens
   • Use secure credential stores (AWS Secrets Manager, Azure Key Vault)
   • Implement automatic key rotation where supported
   • Encrypt credentials at rest
2. Transport Security
   • Enforce TLS 1.3 for all API connections
   • Certificate pinning for critical providers
   • Validate SSL certificates and chains
   • Use connection pooling with security controls
3. Request Sanitization
   • Validate and sanitize all input parameters
   • Prevent injection attacks through request manipulation
   • Implement request size limits
   • Log security events for monitoring
4. Audit and Compliance
   • Log all API requests with sanitized payloads
   • Track usage for compliance reporting
   • Implement data residency controls
   • Support GDPR and other privacy regulations

Performance Optimization

1. Connection Pooling
   • Reuse HTTP connections across requests
   • Configure optimal pool sizes per provider
   • Implement connection lifecycle management
   • Support HTTP/2 multiplexing
2. Intelligent Caching
   • Cache responses based on request patterns
   • Implement cache invalidation strategies
   • Support distributed caching for scalability
   • Optimize cache keys for hit rates
3. Compression and Optimization
   • Enable gzip compression for large payloads
   • Optimize JSON serialization/deserialization
   • Implement request deduplication
   • Use streaming for large responses
4. Load Balancing
   • Distribute requests across provider instances
   • Implement weighted routing based on performance
   • Support geographic routing for latency optimization
   • Monitor and adjust load distribution dynamically

Implementation Plan

Phase 1: Core Infrastructure (Week 1-2)

1. Basic Connection Management
   • HTTP client with connection pooling
   • Provider configuration and registration
   • Basic authentication mechanisms
2. Health Monitoring Foundation
   • Simple health check implementation
   • Basic metrics collection
   • Error logging and alerting

Phase 2: Advanced Features (Week 3-4)

1. Intelligent Routing
   • Provider selection algorithms
   • Load balancing and failover
   • Circuit breaker implementation
2. Enhanced Authentication
   • OAuth 2.0 flow support
   • Token caching and refresh
   • Secure credential management

Phase 3: Production Features (Week 5)

1. Performance Optimization
   • Caching layer implementation
   • Request deduplication
   • Compression and optimization
2. Monitoring and Analytics
   • Comprehensive metrics dashboard
   • Usage analytics and reporting
   • Cost tracking and optimization

Dependencies

• Internal: API Request Validator, Authentication Service, Metrics Service
• External: HTTP client libraries, caching systems, credential stores
• Development: TypeScript 5+, Jest for testing, performance profiling tools

Testing Strategy

1. Unit Tests
   • Connection management logic
   • Authentication mechanisms
   • Error handling scenarios
   • Circuit breaker behavior
2. Integration Tests
   • End-to-end API workflows
   • Provider failover scenarios
   • Performance under load
   • Security and authentication
3. Load Testing
   • Concurrent request handling
   • Provider capacity limits
   • Cache performance
   • Resource utilization

Alternatives Considered

Direct Provider Integration

• Approach: Each service integrates directly with AI providers
  • Pros: Simple implementation, no additional infrastructure
  • Cons: Code duplication, inconsistent error handling, security risks
  • Decision: Centralized approach provides better security and maintainability

Third-Party API Gateway

• Approach: Use external services like Kong, Ambassador, or AWS API Gateway
  • Pros: Proven solutions, extensive features, managed infrastructure
  • Cons: Vendor lock-in, additional costs, limited customization
  • Decision: Custom solution provides better control and AI-specific optimizations

Microservice vs Shared Library

• Approach: Implement as shared library instead of service
  • Pros: Lower latency, simpler deployment, direct integration
  • Cons: Harder to update, less visibility, resource sharing issues
  • Decision: Service approach enables better monitoring and centralized management

Open Questions

1. Provider Expansion: How should we handle new AI providers with unique authentication methods?
2. Cost Optimization: Should we implement automatic cost-based provider selection?
3. Geographic Distribution: How do we handle region-specific provider deployments?
4. Streaming Performance: What optimizations are needed for real-time streaming responses?
5. Compliance: How do we ensure compliance with various data protection regulations?
6. Scalability: What are the horizontal scaling requirements for high-volume scenarios?

Appendix

Glossary

• Circuit Breaker: Design pattern that prevents cascade failures by failing fast when a service is unavailable
• Connection Pooling: Technique to reuse HTTP connections for multiple requests to improve performance
• Provider: External service across any API category (AI models, data stores, integrations, web crawlers) that processes requests
• Health Check: Automated test to determine if a provider is responding correctly across all API types
• Rate Limiting: Mechanism to control the frequency of requests to prevent abuse and stay within provider quotas
• AI Model APIs: External AI service providers (OpenAI, Anthropic, Groq) that offer inference capabilities
• Data Store APIs: External database and storage services (NocoDB, Airtable, Databricks) for data persistence
• Integration APIs: External webhook services, notification systems, and third-party tools for workflow automation
• AI Powered Web Crawlers: Intelligent web scraping services that extract, analyze, and process web content
• Intelligent Routing: Algorithm that selects optimal providers based on performance, availability, and capability matching
• Failover: Automatic switching to backup providers when primary providers become unavailable

References

• Existing Recraft Image Service Implementation
• User Authorization Service Spec
• HTTP Client Best Practices
• Circuit Breaker Pattern

Revision History

• v0.1.0 (2025-08-12): Complete specification with connection monitoring and authentication
• v0.0.0.1 (2025-07-24): Initial file creation