Spring Cloud Features:

Spring Cloud offers a comprehensive set of features tailored for building cloud-ready applications:

Distributed/Versioned Configuration: This feature involves externalizing configuration in a distributed system. With distributed configurations, there's a centralized location to manage properties for applications across various environments.
Service Registration and Discovery: In a distributed environment, all microservices register themselves with a common registry. This enables client-side load-balancing and decouples service providers from consumers, eliminating the need for DNS.
Routing: Spring Cloud assists in routing or forwarding incoming requests to the appropriate downstream services.
Service-to-Service Calls: Microservices communicate with other dependent microservices using a central configuration service and service registry, facilitating seamless service interactions.
Load Balancing: Spring Cloud facilitates the efficient distribution of incoming requests across multiple backend servers or service instances, preventing overload on any single resource within the cluster.
Circuit Breakers: This feature prevents calls to a microservice when it anticipates that the request may fail or time out. By doing so, it conserves valuable client resources that would otherwise be wasted on handling likely-to-fail requests.
Global Locks: Spring Cloud ensures that no two threads simultaneously access the same resource, enhancing data integrity and consistency in certain scenarios.
Leadership Election and Cluster State: Applications can coordinate cluster leadership via third-party systems such as Kubernetes, enabling seamless collaboration among multiple applications.
Distributed Messaging: Spring Cloud facilitates reliable message queuing and delivery to subscribers. Popular libraries for implementing distributed messaging include Apache Kafka and RabbitMQ.

Spring Cloud Components:

Let's match the discussed design patterns with the software components suitable for their implementation:

Distributed/Versioned Configuration:

Implemented using Spring Cloud Configuration Server and Spring Cloud Zookeeper.

Service Registration and Discovery:

Can be implemented using Netflix Eureka, Spring Cloud LoadBalancer, Spring Cloud Zookeeper, and HashiCorp Consul.

Circuit Breaker:

Implemented using Resilience4j and Spring Retry modules.

Distributed Tracing:

Can be implemented using Spring Cloud Sleuth and Zipkin.

Load Balancer:

Implemented using Spring Cloud Gateway and Spring Security OAuth.

Continuous Integration:

Can be implemented using Spring Cloud Pipelines, which internally supports Concourse and Jenkins.

API Virtualization:

Can be added using Hoverfly.

Consumer-Driven Contracts:

Implemented using Spring Cloud Contract.

Service Broker:

Can be implemented using Spring Cloud Open Service Broker.

Lifecycle Management:

Implemented using Spring Cloud Skipper, suitable for multiple Cloud Platforms.

Legacy Components:

Since the Spring Cloud Greenwich (v2.1) release, several Netflix tools have transitioned into maintenance mode within Spring Cloud. This shift is attributed to Netflix's cessation of new feature development for these components, as superior alternatives have emerged.

Netflix Hystrix: Replaced by Resilience4j.
Netflix Hystrix Dashboard/Netflix Turbine: Substituted with Micrometer and a comprehensive monitoring system.
Netflix Ribbon: Replaced by Spring Cloud LoadBalancer.
Netflix Zuul: Replaced by Spring Cloud Gateway.
Archaius: Substituted with Spring Cloud Config.

With the subsequent release of Spring Cloud Ilford (v2020.0.0), the sole remaining Netflix component integrated into Spring Cloud is Netflix Eureka.

Conclusion:

In this brief Spring Cloud tutorial, we have outlined essential design patterns for constructing microservices within a distributed environment. Additionally, we have explored the Spring Cloud modules instrumental in realizing these design patterns within Spring Cloud-based microservices development.

Exploring the Features and Components of Spring Cloud