An Application Programming Interface (API) Gateway is an integral server that is an intermediary for APIs. Its primary role is managing how APIs interconnect with one another and the end-users, simplifying API management. The API Gateway further provides a consolidated control point for implementing API security, monitoring, and various policies.
The main features and responsibilities of an API Gateway include:
- Routing: The API Gateway assigns incoming requests to appropriate services, functioning as a unified access point to the system. This is extremely beneficial in a microservices architecture where multiple independent services exist.
- Request Composition and Decomposition: In a microservices setting, client requests often necessitate processing by multiple services. The API Gateway is adept at decomposing a client's composite request into numerous requests directed to pertinent services. Subsequently, it compiles the responses back into a single comprehensive response.
- Security: The API Gateway enforces stringent security measures such as authentication and authorization, safeguarding the services under its purview. It can verify tokens, restricting access based on predefined roles, amongst other security functions.
- Rate Limiting and Throttling: The API Gateway restricts the requests an API or a client can issue within a specified timeframe to prevent system overload.
- Caching: The API Gateway can enhance system performance by caching responses from backend services. This enables the Gateway to furnish a response from its cache for recurring identical requests instead of redirecting the request to the backend service.
- Monitoring and Analytics: The API Gateway can log request and response data for future analysis, offering insights into API utilization, tracking performance metrics, identifying potential anomalies, and facilitating informed design decisions.
Here are some examples of API gateways:
- Amazon API Gateway (AWS): A fully managed service from Amazon Web Services that makes it easy for developers to create, publish, maintain, monitor, and secure APIs.
- Microsoft Azure API Management: Part of Microsoft's cloud service, this provides developers with the tools they need for end-to-end API management.
- Google Cloud Endpoints: Part of the Google Cloud Platform, this service helps developers to develop, deploy, protect, and monitor APIs.
- Kong API Gateway: An open-source API gateway and platform that acts as middleware between compute clients and API-based applications.
- Apigee: Owned by Google, it's a full lifecycle API management platform that enables API providers to design, secure, deploy, monitor, and scale APIs.
- MuleSoft API Gateway: Part of the MuleSoft Anypoint Platform, it secures and manages traffic for APIs and microservices.
- Express Gateway: An open-source API gateway for microservices built on Express.js.
- Nginx Plus: A software load balancer, web server, and content cache built on open-source Nginx. It has additional features such as request routing and API management.
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