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Advanced Topic 38 of 51 Distributed Systems & Cloud

API Gateway

Single entry point routing and securing API traffic.

How it works

An API gateway is a single entry point for client requests to a set of backend services. It routes requests to the right service, aggregates responses and handles cross-cutting concerns such as authentication and authorization, rate limiting, TLS termination, request and response transformation, caching, logging, metrics and API versioning. Examples include Kong, NGINX, Envoy-based gateways, Amazon API Gateway and Apigee. The backend-for-frontend variant provides tailored gateways per client type.

Where it is used

Microservice back ends exposing public APIs, mobile applications needing aggregated responses and organizations that want consistent security and observability use gateways.

Common pitfall

The gateway can become a single point of failure and a bottleneck, and putting business logic in it creates a hidden monolith. Extra hops add latency. Misconfigured routing or authentication rules expose services. Keep it thin, deploy it redundantly and horizontally scaled, automate configuration through code and avoid coupling it to service internals.

Where it fits in the course

API Gateway is topic 38 of 51 in Distributed Systems & Cloud, rated Advanced. It follows Service Discovery. The next topic is Service Mesh.

Practice and explore

How to study this topic

  1. Read the explanation above and restate the definition in your own words.
  2. Open the interactive lesson and answer its mini quiz.
  3. Read the common pitfall, then write a short example that avoids it.
  4. Check your understanding in the Distributed Systems & Cloud quiz, and revisit the topic if you miss a question.

Frequently asked questions

What is API Gateway?
Single entry point routing and securing API traffic. It belongs to Distributed Systems & Cloud and is an advanced-level topic.
Where do people use API Gateway?
Microservice back ends exposing public APIs, mobile applications needing aggregated responses and organizations that want consistent security and observability use gateways.
What is the most common mistake with API Gateway?
The gateway can become a single point of failure and a bottleneck, and putting business logic in it creates a hidden monolith.
What should I learn before this topic?
Start with Service Discovery, the topic just before it in Distributed Systems & Cloud.
How can I practice it?
Answer the mini quiz in the interactive lesson, then take the Distributed Systems & Cloud quiz.
Is API Gateway hard to learn?
It is an Advanced topic. Expect to read the explanation more than once and to connect it with earlier topics. Working through a small example by hand helps most.
How long does it take to learn API Gateway?
Most learners can read the explanation and finish the interactive lesson in under an hour. Fluency comes from applying the idea, so plan a few short practice sessions with the quiz.
Which topics are related to API Gateway?
Service Discovery, Service Mesh, Apache Spark are closely connected. The full list is in the related topics section of this page.
What should I study after API Gateway?
Continue with Service Mesh, the next topic in Distributed Systems & Cloud.

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