For this series we will use group id as com.example.microservices and artifact id as micro-services name.
- artificat
limitservices, port8080
Dependencies used
- Web
- DevTools
- Actuator
- Config Client
application.properties
spring.application.name=limit-services
xyz.minimum=99
xyz.maximum=99999
Read application.properties using @ConfigurationProperties
Configuration.java
@Component
@ConfigurationProperties("xyz")
public class Configuration {
private int minimum;
private int maximum;
public int getMinimum() {
return minimum;
}
public int getMaximum() {
return maximum;
}
public void setMinimum(int minimum) {
this.minimum = minimum;
}
public void setMaximum(int maximum) {
this.maximum = maximum;
}
}Autowire Component inside RestController and read value from properties using Configuration class
@RestController
public class LimitsConfigurationController {
@Autowired
private Configuration configuration;
@GetMapping("api/v1/limits")
public LimitConfiguration retriveLimitsFromConfigurations() {
return new LimitConfiguration(configuration.getMaximum(), configuration.getMinimum());
}
}Used dependencies are Spring Web, Config Client. Optional Dependencies Spring Boot DevTools, Spring Boot Actuator.
- To make use of db using
h2databasewithspring-data-jpa.
Used dependencies are Spring Web, Config Client. Optional Dependencies Spring Boot DevTools, Spring Boot Actuator.
@RestController
public class CorrencyConversionController {
@GetMapping("/currency-converter/from/{from}/to/{to}/quantity/{quantity}")
public CurrencyConversionBean convertCurrency(@PathVariable String from, @PathVariable String to, @PathVariable BigDecimal quantity) {
Map<String, String> uriVariables = new HashMap<String, String>();
uriVariables.put("from", from);
uriVariables.put("to", to);
ResponseEntity<CurrencyConversionBean> responseEntity = new RestTemplate()
.getForEntity("http://localhost:8000/currency-exchange/from/{from}/to/{to}", CurrencyConversionBean.class, uriVariables);
CurrencyConversionBean response = responseEntity.getBody();
return new CurrencyConversionBean(response.getId(), from, to, response.getConversionMultiple(), quantity, quantity.multiply(response.getConversionMultiple()), response.getPort());
}
}Create a interface for proxy
@FeignClient(name = "currency-exchange-service", url = "localhost:8000")
public interface CurrencyExchangeServiceProxy {
@GetMapping("/currency-exchange/from/{from}/to/{to}")
public CurrencyConversionBean retrieveExchnageValue(@PathVariable String from, @PathVariable String to);
}And make use of this proxy instead of RestTemplate
@RestController
public class CorrencyConversionController {
@Autowired
private CurrencyExchangeServiceProxy proxy;
// Same as above code but using feign proxy
@GetMapping("/currency-converter-feign/from/{from}/to/{to}/quantity/{quantity}")
public CurrencyConversionBean convertCurrencyFeign(@PathVariable String from, @PathVariable String to, @PathVariable BigDecimal quantity) {
CurrencyConversionBean response = proxy.retrieveExchnageValue(from, to);
return new CurrencyConversionBean(response.getId(), from, to, response.getConversionMultiple(), quantity, quantity.multiply(response.getConversionMultiple()), response.getPort());
}
}Feign helps us to simplyfy the client code to talk to restful services.
Add ribbon dependency
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
<version>2.2.8.RELEASE</version>
</dependency>
Add annotation @Ribbon(name="currency-exchange-service") on feign proxy interface
Now we can remove the url from @FeignClient()
//@FeignClient(name = "currency-exchange-service", url = "localhost:8000")
@FeignClient(name = "currency-exchange-service")
@RibbonClient(name = "currency-exchange-service")
public interface CurrencyExchangeServiceProxy {
@GetMapping("/currency-exchange/from/{from}/to/{to}")
public CurrencyConversionBean retrieveExchnageValue(@PathVariable String from, @PathVariable String to);
}Configure application.properties with list of urls
spring.application.name=currency-conversion-service
server.port=8100
spring.config.import=optional:configserver:
currency-exchnage-service.ribbon.listOfServers=http://localhost:8000, http://localhost:8001
Create a new project with Eureka Server, Config Client, Spring Boot Actuator and Spring Boot DevTools dependencies
Annotate main class with @EnableEurekaServer
@SpringBootApplication
@EnableEurekaServer
public class NetflixEurekaNamingServerApplication {
public static void main(String[] args) {
SpringApplication.run(NetflixEurekaNamingServerApplication.class, args);
}
}Add following inside application.properties
spring.application.name=netflix-eureka-naming-server
server.port=8761
spring.config.import=optional:configserver:
eureka.client.register-with-eureka=false
eureka.client.fetch-registry=false
After running application eureka server should be up and running
Open pom.xml of currency-conversion-service and add following dependency
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
Add @EnableDiscoveryClient like following
@SpringBootApplication
@EnableFeignClients("com.example.microservices.currencyconversionservice")
@EnableDiscoveryClient
public class CurrencyConversionServiceApplication {
public static void main(String[] args) {
SpringApplication.run(CurrencyConversionServiceApplication.class, args);
}
}Configure url for eureka inside application.properties of currency-conversion-service
eureka.client.service-url.default-zone=http://localhost:8761/eureka
Run application and it will register itself with eureka-naming-server.
Repeat above steps for currency-exchange-service
All Instance should be running with eureka after starting services.
Start multiple instance of same service on different port and you will see with the help of naming server load is being distributed.
- Authentication, Authorization And Security
- Rate Limits
- Fault tolearation
- Service Aggregation
Yureka zul and atomic