Step 1: Create or Use the currency-exchange-service
Ensure that you have a working currency-exchange-service that provides exchange rate information for different currency pairs. This service should have API endpoints to fetch exchange rates.
Step 2: Configure the currency-conversion-service
In the currency-conversion-service, you need to configure how to communicate with the currency-exchange-service. This configuration should include the base URL of the currency-exchange-service.
In Spring Boot, you can define the base URL in the application.properties or application.yml file:
currency.exchange.service
.url=http://currency
-exchange-service-url
Step 3: Create a REST Template or Use WebClient
To make HTTP requests to the currency-exchange-service, you can use either RestTemplate or WebClient, depending on your preference and the version of Spring you are using.
Here’s an example of how to do it using RestTemplate:
@RestController
public class CurrencyConversionController
{
@Value("${currency.exchange.service.url}")
private String exchangeServiceBaseUrl;
@Autowired
private RestTemplate restTemplate;
@GetMapping
("/currency-converter/from/{from}/to
/{to}/quantity/{quantity}")
public CurrencyConversion convertCurrency(
@PathVariable String from,
@PathVariable String to,
@PathVariable BigDecimal quantity
) {
// Make an HTTP request to currency
-exchange-service
ResponseEntity<CurrencyConversion> response
= restTemplate.exchange(
exchangeServiceBaseUrl
+ "/currency-exchange/from/{from}/to/{to}",
HttpMethod.GET,
null,
CurrencyConversion.class,
from, to
);
CurrencyConversion exchangeRate =
response.getBody();
// Calculate the total calculated amount
BigDecimal totalCalculatedAmount
= exchangeRate
.getConversionRate().multiply(quantity);
// Create a CurrencyConversion object
return new CurrencyConversion(
exchangeRate.getId(),
from,
to,
quantity,
exchangeRate.getConversionRate(),
totalCalculatedAmount,
exchangeRate.getPort()
);
}
}
The above code sends an HTTP GET request to the currency-exchange-service to fetch the exchange rate for the given currency pair (from and to). It then calculates the total converted amount and constructs a CurrencyConversion response.
Step 4: Run and Test
Run the currency-conversion-service and test it by making HTTP requests to the /currency-converter endpoint. Ensure that it can successfully retrieve exchange rates from the currency-exchange-service and perform currency conversion.
By following these steps, you can invoke the currency-exchange-service from the currency-conversion-service to get exchange rates and perform currency conversions in a microservices architecture. Make sure to handle error scenarios, implement proper exception handling, and consider security aspects as needed in your application.
