Section 1.1: Understanding Service Discovery

With recent updates, the Service Discovery annotation is no longer mandatory; you can directly register the DiscoverClient as a Bean. Alternatively, the annotation can still be used to search for configurations in META-INF/spring.factories, allowing you to register its associated values as Beans.

Section 1.3: Service Registration Mechanisms

Spring Cloud Commons introduces a ServiceRegistry interface, which includes methods like register(Registration) and deregister(Registration). This allows for custom registration services. Here’s an example:

@Configuration

@EnableDiscoveryClient(autoRegister=false)

public class PackConfig {

private final ServiceRegistry registry;

public PackConfig(ServiceRegistry registry) {

this.registry = registry;

}

public void register() {

Registration registration = // Your service instance information;

this.registry.register(registration);

}

}

Section 2.1: Monitoring Service Registration Events

When automatic registration occurs, an InstancePreRegisteredEvent is emitted before the registration process, followed by an InstanceRegisteredEvent afterward, allowing us to listen for these events.

The first video, "The Beginner's Guide To Spring Cloud," provides an introduction to the basic features and functionalities of Spring Cloud, perfect for newcomers.

Section 2.2: Load Balancing with RestTemplate

You can set up a RestTemplate to utilize the load balancer client. To create a load-balanced RestTemplate, simply declare a RestTemplate @Bean and include the @LoadBalanced annotation:

@Configuration

public class PackConfig {

@LoadBalanced

@Bean

RestTemplate restTemplate() {

return new RestTemplate();

}

}

In your service class, you can make requests to the order service seamlessly, achieving load balancing:

@Service

public class UserService {

private final RestTemplate restTemplate;

public UserService(RestTemplate restTemplate) {

this.restTemplate = restTemplate;

}

public String query() {

String results = restTemplate.getForObject("http://order-service/orders/666", String.class);

return results;

}

}

Section 2.3: Load Balancing with WebClient

Similarly, you can configure a WebClient for automatic load balancing. Here's how to create a load-balanced WebClient:

@Configuration

public class PackConfig {

@Bean

@LoadBalanced

public WebClient.Builder loadBalancedWebClientBuilder() {

return WebClient.builder();

}

}

In the service, you can utilize the WebClient as follows:

@Service

public class UserService {

private final WebClient.Builder webClientBuilder;

public UserService(WebClient.Builder webClientBuilder) {

this.webClientBuilder = webClientBuilder;

}

public Mono<String> doOtherStuff() {

return webClientBuilder.build().get().uri("http://order-service/orders/666")

.retrieve().bodyToMono(String.class);

}

}

The second video, "Getting Started with Spring Cloud," walks you through practical implementations and configurations in Spring Cloud, ideal for beginners and seasoned developers alike.

Section 3.1: Managing Multiple RestTemplate Instances

For cases where a non-load-balanced RestTemplate is needed, you can create a standard RestTemplate bean. To access a load-balanced RestTemplate, utilize the @LoadBalanced qualifier:

@Configuration

public class MyConfiguration {

@LoadBalanced

@Bean

RestTemplate loadBalanced() {

return new RestTemplate();

}

@Primary

@Bean

RestTemplate restTemplate() {

return new RestTemplate();

}

}

Section 3.2: Ignoring Specific Network Interfaces

Sometimes, it’s beneficial to exclude certain network interfaces from service discovery registration, particularly in Docker environments. You can specify which interfaces to ignore with regular expressions:

spring:

cloud:

inetutils:

ignoredInterfaces:

• docker0
• veth.*

Section 3.3: Custom HTTP Client Factories

Spring Cloud Commons supports the creation of Apache HTTP clients and OK HTTP clients via beans. You can customize their creation in downstream projects by providing your implementations.

Section 3.4: Developing Custom Features

You can build and include custom features in a jar, with a manifest file structured similarly to this:

Manifest-Version: 1.0

Implementation-Title: Spring Cloud Commons RPC

Implementation-Version: 1.0.1

Build-Jdk-Spec: 17

Created-By: Your Name

Implementation-Vendor: Your Company

This allows Spring Cloud to recognize and utilize your custom features effectively.