What is a gateway API?

Role and tasks of API gateway

The API gateway acts as an intermediary and manager of API traffic, performing a number of important tasks:

• Request Routing: Routing incoming requests to appropriate microservices or backend functions based on URL path, headers or other criteria.
• Response aggregation: Combining responses from multiple different backend services into a single, consistent response for the client, reducing the number of client-side network requests.
• Protocol translation: Enabling communication between clients using different protocols and backend services (e.g., a client uses REST and a service uses gRPC).
• Authentication and authorization: centrally manage the process of verifying a client’s identity (authentication) and checking its authorization to invoke individual services (authorization), thereby offloading the burden on backend services.
• Limiting the number of requests (Rate Limiting) and protecting against abuse (Throttling): Placing limits on the number of requests a given client can send in a given period of time to protect the system from overloading and Denial of Service (DoS) attacks.
• Logging and monitoring: Centrally collect logs and metrics on API traffic to facilitate monitoring, analysis and debugging.
• Caching: Storing frequently repeated responses in a cache to reduce the load on backend services and speed up responses for the client.
• Transforming requests and responses: Modify incoming requests or outgoing responses to adjust their format or content.

Benefits of using API gateway

There are many benefits to implementing an API gateway in a distributed architecture:

• Simplify communication for customers: Customers communicate with only one entry point, and do not need to know the addresses and specifics of each microservice.
• Hermetization of the internal structure: Hiding the complexity of the backend architecture from customers.
• Centralization of cross-cutting tasks: Focusing tasks such as authentication, authorization, rate limiting, and logging in one place, which simplifies the logic of individual microservices.
• Enhanced security: Central access control and fraud protection.
• Improved performance: Ability to cach and aggregate responses.
• Easier API management and monitoring.

Challenges and potential drawbacks

The API gateway, while being a central point of entry, can also become a single point of failure (single point of failure) if not properly designed for high availability and scalability. It can also introduce additional delay (latency) in processing requests. It also runs the risk of becoming an overly complex component (a “God object”) if it takes on too much logic.

Gateway API implementations

There are many off-the-shelf API gateway solutions available on the market, both commercial and open-source, as well as services offered by cloud providers:

• Cloud-based: AWS API Gateway, Azure API Management, Google Cloud API Gateway.
• Open-source: Kong, Tyk, Apache APISIX, Spring Cloud Gateway.
• Commercial: Apigee (Google), MuleSoft Anypoint Platform.

Summary

API gateway is a key architectural pattern in modern distributed systems, especially those based on microservices. It acts as a central entry point for client requests, simplifying communication, centralizing cross-cutting tasks (like security or monitoring) and hiding the complexity of the backend architecture. Using an API gateway significantly simplifies building and managing scalable and secure APIs.