API Gateway

A client can contact microservices in a variety of ways. One approach is to directly call the microservice. This strategy is simple and effective for a limited number of microservices. With complicated systems, this technique has substantial drawbacks such as noisy interfaces, non-centralized authentication, data transformation, and no data payload optimisation based on client type. With microservice endpoint updates, we must also deploy the client application. This creates a close relationship between the client and the server.

The diagram below shows the interaction with microservices in without the use of an API gateway.

For these scenarios, we can use API gateway which acts as a façade for a distributed system, and as a reverse proxy that hides the complexity of microservice routing. In the case of microservice service endpoint changes, we only need to change the mapping on API gateway without client deployment. Now, microservices behind API gateway can be scaled in or out at will. The API gateway also provides additional functionalities like logging, centralized authentication/authorization, secure communication, service discovery, response caching, rate limiting, data compression, data transformation, and so on. We can also create a separate API gateway based on the client type to configure data compression and transformation as needed.

The following diagram shows different clients communicating with microservices using their respective API gateways, making it resilient to failure and customizable.

Why Do We Need an API Gateway?

An API Gateway is essential for simplifying the management, security, and scalability of microservices. It acts as a central control point, allowing for centralized API management, security enforcement, and load balancing. API Gateways provide features like authentication, rate limiting, and caching to protect services from unauthorized access and DDoS attacks. They enable the aggregation and transformation of data from multiple services, optimizing client interactions. Additionally, API Gateways offer critical logging, monitoring, and analytics capabilities for better visibility and performance optimization. Ultimately, they enhance the overall efficiency and security of microservices while providing a streamlined experience for clients.

Summary

An API Gateway is a vital component in modern software architecture, serving as an intermediary between clients and microservices. It streamlines API management by centralizing functions like authentication, authorization, rate limiting, and security. It enhances performance through load balancing and caching, while offering essential logging and monitoring capabilities. API Gateways also enable data aggregation and transformation, simplifying complex interactions. They support version control, ensuring backward compatibility, and simplify the client experience. By providing a unified entry point for APIs, they facilitate efficient, secure, and scalable interactions in microservices architectures.