Handling exception while calling external API using apache camel?

Question

I need to call dowstream service Service B (given api contract) from my service, Service A , which is being called by the upstream systems.

Now I am using apache camel service instance for making a call to Service B , as given below:

Request and Responses :

public abstract class CamelRequest {
    private String route
}
public abstract class CamelResponse {
}
public class ServiceBRequest extends CamelRequest {
  // some fields are here
}
public class ServiceBResponse  extends CamelResponse {
   // some fields are here
}

CamelService.java:

import org.apache.camel.CamelExecutionException;
import org.apache.camel.ProducerTemplate;

public abstract class CamelService {

    @Autowired
    private ProducerTemplate template;
    
    protected abstract void preProcessor(CamelRequest req);
    protected abstract void postProcessor(CamelResponse res);

    public CamelResponse process(CamelRequest req, Map<String, Object> headers) throws CamelExecutionException {
    CamelResponse response = template.requestBodyAndHeaders(getRoute(req), req, headers, CamelResponse.class);
    log.debug(req.getRoute()+":: "+returnMetricsMessageHistoryService());
    return response;
    }

    private String getRoute(CamelRequest req) {
    return req.getRoute();
    }
}

ServiceBImpl.java:

public class ServiceBImpl extends CamelService {
    @Override
    public void preProcessor(CamelRequest req) {
    //Do nothing because no validation exist on downstream request object
    }

    @Override
    public void postProcessor(CamelResponse res) {
    //Do nothing because no validation exist on downstream response object
    }
}

Call to downstream service service B :

public ServiceBResponse callServiceB(ServiceBRequest req, Map<String, Object> headers)
        throws CamelExecutionException{
    CamelService serviceBImpl = new ServiceBImpl();
    ServiceBResponse resp = (ServiceBResponse) serviceBImpl.process(req, headers);
    return resp;
}

Now when we call serviceB as:

template.requestBodyAndHeaders(getRoute(req), req, headers, CamelResponse.class);

this method throws CamelExecutionException .

I need to figure out what possible exceptions can be wrapped inside this CamelExecutionException, so that I can handle them separately OR do different custom logging for different exceptions.

 For instance, for one exception:
 if(exception.getCause() instanceof java.util.concurrent.TimeoutException) 
 {//do something }

What is the correct way to find out possible exceptions wrapped inside CamelExecutionException while calling an API?

Answer 1

     catch(CamelExecutionException camelException){

        Exception exchangeException = camelException.getExchange().getException();

        if (exchangeException != null && exchangeException.getCause() instanceof GoogleJsonResponseException) {

            GoogleJsonResponseException originalException = (GoogleJsonResponseException) exchangeException.getCause();

            return Response.status(originalException.getStatusCode()).build();
        }
        throw e;
    }

OR

catch(CamelExecutionException camelException){

        final Throwable cause = camelException.getCause();

        if (cause instanceof HttpOperationFailedException) {
            final HttpOperationFailedException httpError = (HttpOperationFailedException) cause;
        }

        throw camelError;

    }