第1个回答 2024-08-21
Eurake, a service discovery component from Netflix, operates through Eureka Server and Eureka Client components. The self-protection mechanism in Eureka Server helps to avoid accidental service removal by setting a threshold for the failure rate of heartbeats. If the failure rate in 15 minutes is below 85%, the Eureka Server enters self-protection mode. In this mode, the server displays a warning message and adjusts its behavior to prevent the mass removal of instances, safeguarding the system's availability in microservices architecture.
The Eureka Client is a Java client that simplifies interactions with the Eureka Server. It fetches, updates, and caches information from the Eureka Server, allowing service consumers to find service providers even when all Eureka Server nodes are down, albeit with potential inconsistency when services change. Eureka Server utilizes a dual-layered ConcurrentHashMap for data storage and implements a caching mechanism to enhance response times. The server's first cache retrieves information, followed by the second cache when the first fails to provide the data. If neither cache provides the necessary data, the server synchronizes with the storage layer and retrieves the information from there.
There are other cache mechanisms in play, such as those in the Eureka Client, which fetches a full list of services upon startup and periodically updates this list from the Eureka Server. If a partial update fails or the hashcode comparison indicates inconsistency, a full refresh occurs. Ribbon, a load balancer integrated with Eureka, also maintains its own cache, updated every 30 seconds from the Eureka Client cache.
Configurations for Eureka Server, Client, and Instances include settings for server timeouts, client heartbeats, and other parameters. Eureka Server operates in a cluster through replication, allowing for high availability without designating a primary node. The system can handle node failures without impacting service availability.
Eureka's consistency protocol ensures that data is eventually consistent across nodes, even in the face of node failures. The service registration process involves the client sending heartbeats to the server, which removes unresponsive instances after a period of inactivity.
Zuul, a Netflix gateway solution, enables routing and proxying of client requests to the appropriate services. Feign, a microservices client, simplifies service invocation by generating proxies and integrating with other components like Ribbon for load balancing and Hystrix for circuit breaker mechanisms.
Feign employs dynamic proxies for service invocation, integrating with Hystrix for circuit breaker functionality and Ribbon for load balancing. The Feign framework automates the proxy generation process, allowing developers to focus on service contracts rather than low-level proxy creation.
Ribbon Netflix's load balancer component is used in service consumer applications to distribute traffic among services. Hystrix, an isolation and circuit breaker framework, prevents cascading failures by isolating services and managing their interactions. Spring Cloud Gateway, an API gateway for microservices, provides a unified way to manage routing and access control.
The Spring Cloud Config server and client support distributed configuration management, while Spring Cloud Bus facilitates message passing for event-driven architectures. OAuth2 in Spring Cloud provides security for microservices, ensuring secure access and authentication.
Spring Cloud Sleuth is a tracing solution for distributed systems, tracking service interactions and providing visibility into the application's behavior. These components, along with the core Eureka and Feign components, form a comprehensive ecosystem for building and managing modern microservices architectures.