Catalog
concept#Integration#Architecture#Observability#Security

API Gateway

Central runtime component that consolidates client requests, secures, transforms and routes them to backend services.

An API gateway is a centralized runtime component that accepts client requests, authenticates, authorizes, routes and optionally transforms them.
Established
Medium

Classification

  • Medium
  • Technical
  • Architectural
  • Intermediate

Technical context

Identity providers (OAuth2, OpenID Connect)Logging and tracing systems (ELK, Prometheus, Jaeger)Service mesh or reverse proxies

Principles & goals

Consolidate interfaces at a single pointSeparate interface management from business logicExplicit management of authentication, authorization and traffic
Build
Enterprise, Domain, Team

Use cases & scenarios

Compromises

  • Gateway overload impacts all clients
  • Misconfiguration can expose security vulnerabilities
  • Excessive logic in the gateway leads to monolithization
  • Keep gateways slim: leave business logic in the backend
  • Automated testing and canary rollouts
  • Centralized monitoring and structured alerts

I/O & resources

  • Definition of API endpoints and contracts
  • Security and authentication requirements
  • Monitoring and observability tools
  • Controlled and secured API access
  • Metrics, logs and traces for operations
  • Reduced coupling between clients and backends

Description

An API gateway is a centralized runtime component that accepts client requests, authenticates, authorizes, routes and optionally transforms them. It abstracts backend services, consolidates interfaces, and provides rate limiting, monitoring and protocol translation. Gateways are key in distributed architectures and influence performance, resilience and operational costs.

✔

  • Reduced coupling between clients and backends
  • Central enforcement of security and rate-limit policies
  • Improved observability and monitoring touchpoints

✖

  • Single point of failure without proper redundancy
  • Additional latency from routing and transformations
  • Complexity in versioning and migration paths

  • Requests per second

    Throughput measurement, important for capacity planning.

  • P95/P99 latency

    Latency percentiles to monitor performance SLAs.

  • Error rate

    Share of failed responses, important for resilience metrics.

Enterprise API portal

Central gateway that authenticates external partner requests, applies limits and routes to internal microservices.

Mobile backend aggregation

Gateway aggregates multiple backend calls into a single optimized API for mobile clients.

Legacy adapter

Gateway provides translators for legacy SOAP services and exposes modern REST endpoints.

1

Requirements analysis and interface definition

2

Prototype with minimal routing and authentication functionality

3

Staging rollout, load tests and gradual production routing

⚠️ Technical debt & bottlenecks

  • Ad-hoc policies without documentation
  • Hardcoded routes instead of configurable rules
  • Missing automation for certificate rotation
Latency due to transformationsScaling gateway instancesComplexity of policies and rules
  • Moving service integration tasks into the gateway instead of services
  • Relying on gateway-specific proprietary features without abstraction
  • Uncontrolled addition of transformation rules without tests
  • Underestimating operational effort for security certificates
  • Missing capacity planning for peak loads
  • Hidden costs due to high throughput requirements
Knowledge of API design and versioningOperational knowledge for scaling and high availabilitySecurity expertise (AuthN/AuthZ, TLS)
Security and access controlScalability and performanceObservability and operational metrics
  • • Network latency and bandwidth limits
  • • Compatibility with existing authentication mechanisms
  • • Regulatory requirements for logging and data protection