Invoking currency-exchange-service from currency-conversion-service

We have the currency-exchange-service ready, and we have set up a currency-calculation-service (currency-conversion-service). Now we will invoke the currency exchange service from the currency calculation service.

We use RestTemplate() constructor to invoke an external service. Let's create a RestTemplate and try to invoke currency-exchange-service.

Step 1: Select the currency-conversion-service project.

Step 2: Open the CurrencyConversionController.java and create a new RestTemplate that invokes the currency-exchange-service application.

Step 3: Invoke the getForEntity() method of RestTemplate class.

getForEntity(): It is a method of RestTemplate class that retrieves an entity by using the HTTPGET method for the specified URL. It converts and stores the response in the ResponseEntity. It returns the ResponseEntity.

Parameters: It accepts two parameters:

URL: The URL.
responseType: The type of the return value.

ResponseEntity<CurrencyConversionBean>responseEntity=new RestTemplate().getForEntity("http://localhost:8000/currency-exchange/from/{from}/to/{to}", CurrencyConversionBean.class, uriVariables);

Step 4: In the URL parameter, put the URL of currency-converter-service that is http://localhost:8000/currency-exchange/from/{from}/to/{to}. It takes values from the variable {from} and {to} from the request. Whatever comes in the request we sent it to the currency-exchange-service.

Step 5: In the above URL, we need to pass two values "from" and "to." For passing the values, create a Map for URI variables. Pass the uriVariables in the URI as a parameter.

Map<String, String>uriVariables=new HashMap<>();
uriVariables.put("from", from);
uriVariables.put("to", to);

Step 6: The response type that we are expecting back is CurrencyConversionBean, so store the response in the CurrencyConversionBean.

CurrencyConversionController.java

package com.javatpoint.microservices.currencyconversionservice;
import java.math.BigDecimal;
import java.util.HashMap;
import java.util.Map;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
@RestController
public class CurrencyConversionController
{
@GetMapping("/currency-converter/from/{from}/to/{to}/quantity/{quantity}") //where {from} and {to} represents the column 
//returns a bean back
public CurrencyConversionBeanconvertCurrency(@PathVariable String from, @PathVariable String to, @PathVariableBigDecimal quantity)
{
//setting variables to currency exchange service
Map<String, String>uriVariables=new HashMap<>();
uriVariables.put("from", from);
uriVariables.put("to", to);
//calling the currency-exchange-service
ResponseEntity<CurrencyConversionBean>responseEntity=new RestTemplate().getForEntity("http://localhost:8000/currency-exchange/from/{from}/to/{to}", CurrencyConversionBean.class, uriVariables);
CurrencyConversionBean response=responseEntity.getBody();
//creating a new response bean and getting the response back and taking it into Bean
return new CurrencyConversionBean(response.getId(), from,to,response.getConversionMultiple(), quantity,quantity.multiply(response.getConversionMultiple()),response.getPort());
}
}

Step 7: Run the both services independently. When we run the currency conversion, it returns the response shown below:

Setting up Currency Conversion Microservice

The conversion Multiple is multiplied by the quantity and returns the totalCalculatedAmount 65000.00. It means $1000 is equal to 65000.00 INR. It also shows the port 8000 that denotes the other service (currency-exchange-service) is running on port 8000.

Click here to download currency-conversion-service

Click here to download currency-exchange-service

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