API Gateway is an intermediate layer between clients and backend services that manages and controls API requests initiated from clients. API Gateway has the following functions:
Request routing and requesting: API Gateway can route requests based on information such as the URL, method, and header of the request. It can send requests to the appropriate service instance on the backend, implement load balancing and flow control, and ensure that requests are processed and responded to correctly.
Service aggregation: When a client needs to obtain data from multiple backend services, API Gateway can aggregate requests from different services and return the combined results to the client, reducing the number of requests from the client and improving performance.
Security authentication and authorization: API Gateway can handle authentication and authorization mechanisms, such as using API keys and access tokens for client authentication. It verifies the legitimacy of the request and authorizes or denies the request according to the preset access policy, ensuring that only authorized clients can access the corresponding API.
Request Translation and Protocol Transformation: API Gateway can convert requests from different clients into different request formats (such as JSON and XML) into formats that can be understood by backend services. It can also convert requests from one protocol (e.g., HTTP) to another (e.g., WebSocket) to meet the communication needs between different services.
Caching and data response: API Gateway can cache part of the response data to speed up the response and reduce the pressure on backend services. It stores and manages responses based on caching policies, and uses cached data to respond to repetitive requests when appropriate, providing faster access.
Analysis and monitoring: API Gateway can collect and analyze request and response data to provide real-time monitoring and logging. It helps developers and administrators track the behavior and performance of requests, and provides a basis for troubleshooting and performance optimization.
API gateways play a key role in modern application architectures. It serves as an entry point and provides features such as routing, security, performance optimization, monitoring, and management of API requests. By centrally processing and managing API requests, API Gateway can improve the security, reliability, and maintainability of applications, while simplifying communication between clients and backend services. At present, the commonly used API gateways in the J**A camp are Zuul and SpringCloud Gateway, both of which are components used to build API gateways in the Spring Cloud framework, and they have the following differences:
Technical architecture: Zuul is a servlet 2 based on the blocking IO modelX container, while Spring Cloud Gateway is built on a non-blocking IO model using the Spring Framework 5, Spring Webflux, and Project Reactor stacks.
Performance and scalability: Since Spring Cloud Gateway uses the asynchronous non-blocking model of Webflux and Reactor, it has better performance in terms of IO processing power, concurrent connection processing, and request response processing speed than Zuul's synchronous blocking model. At the same time, the architecture of Spring Cloud Gateway is also more suitable for building a highly available and scalable API gateway, which can achieve better horizontal scaling and is suitable for large-scale and high-concurrency distributed systems.
Flexibility of gateway components: Spring Cloud Gateway provides a more flexible filter mechanism, which can customize filter chains, routing rules, and methods, making it easier than Zuul to extend and customize the functions and behaviors of the gateway.
Lifecycle management of APIs: Spring Cloud Gateway provides a lifecycle and health check mechanism consistent with Spring Framework, which can support dynamic refresh and reloading of routing rules and processors for real-time configuration and deployment.
Community support and development: At present, Spring Cloud Gateway, as a member of the Spring Cloud family bucket, has received wider attention and support in the Spring community, and maintains a strong update and development trend.
Both Zuul and Spring Cloud Gateway have their own advantages and disadvantages and adaptation scenarios, which should be selected according to specific business needs. If you need more performance and scalability, but also want more flexible configuration and customization, you can choose Spring Cloud Gateway. And if you need more functions and a stable operating environment, you can choose Zuul.
In high-concurrency and potentially high-latency scenarios, a basic requirement for gateways to achieve high performance and high throughput is full-link asynchronous and not blocking threads. The Zuul gateway uses synchronous blocking mode, which does not meet the requirements.
Spring Cloud Gateway is based on WebFlux, which perfectly supports asynchronous non-blocking programming, and many functions are easy to implement. Spring5 must use J**A 8, functional programming is one of the important features of J**A8, and WebFlux supports functional programming to define routing endpoints to handle requests.
Through the above implementation, the gateway was migrated from Zuul to Spring Cloud Gateway. Rich routing assertions and filters are defined in the gateway, which can be directly called and used through configuration files or Fluent APIs, which is very convenient. In terms of performance, it is also better than the previous Zuul gateway.