API Gateway pattern in Microservices - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Role of API Gateway in Microservices Architecture

Which of the following best describes the primary role of an API Gateway in a microservices architecture?

A It directly manages the deployment and scaling of individual microservices.

B It acts as a single entry point that routes client requests to appropriate microservices and handles cross-cutting concerns like authentication and rate limiting.

C It replaces the need for microservices by combining all services into one monolithic application.

D It stores all the data for microservices and manages database transactions across services.

💡 Hint

Think about what a single point of contact for clients would do in a system with many small services.

The API Gateway acts as a single entry point for clients. It routes requests to the correct microservice and handles common tasks like authentication, logging, and rate limiting, simplifying client interactions.

❓ Architecture

intermediate

API Gateway Request Flow

In an API Gateway pattern, what is the correct sequence of steps when a client sends a request?

A 2,1,3,4,5

B 1,2,4,3,5

C 1,3,2,4,5

D 1,2,3,4,5

💡 Hint

Authentication usually happens before routing the request to a service.

The client first sends the request to the API Gateway. The gateway authenticates the request, then routes it to the correct microservice. The microservice processes it and returns the response to the gateway, which then sends it back to the client.

❓ scaling

advanced

Scaling Challenges with API Gateway

What is a common scaling challenge when using an API Gateway in a large microservices system?

A The API Gateway can become a bottleneck if it cannot handle the volume of incoming requests efficiently.

B The API Gateway automatically scales all microservices regardless of their load.

C Microservices lose their ability to communicate with each other directly.

D Clients must connect to each microservice individually, increasing complexity.

💡 Hint

Consider what happens if one component handles all incoming traffic.

The API Gateway handles all client requests, so if it is not scaled properly, it can slow down the entire system. Proper load balancing and horizontal scaling of the gateway are necessary to avoid bottlenecks.

❓ tradeoff

advanced

Tradeoffs of Using an API Gateway

Which of the following is a tradeoff when implementing an API Gateway pattern?

A It removes the need for authentication and security measures in microservices.

B It eliminates the need for microservices, reducing system complexity.

C It simplifies client communication but adds an extra network hop, potentially increasing latency.

D It guarantees zero downtime during microservice deployments without additional configuration.

💡 Hint

Think about what happens when you add an extra step in communication.

While the API Gateway simplifies client interactions by centralizing routing and security, it introduces an additional network hop. This can increase latency slightly and requires careful design to minimize impact.

❓ estimation

expert

Capacity Estimation for API Gateway

You expect 10,000 client requests per second to your microservices system. Each request passes through the API Gateway, which adds 5ms processing overhead per request. Your microservices handle requests in 50ms on average. What is the minimum number of API Gateway instances needed to keep average API Gateway processing latency under 20ms assuming each instance can handle 2,000 requests per second?

A 5 instances

B 10 instances

C 2 instances

D 20 instances

💡 Hint

Calculate how many requests per second each instance can handle and divide total load accordingly.

Each instance can handle 2,000 requests per second. For 10,000 requests, you need at least 5 instances (10,000 / 2,000 = 5). This keeps processing latency under 20ms by avoiding overload.