Propagate exception from CXF interceptor to exception mapper

Question

I've a flow where on CXF client I've jaxrs-in-interceptor, provider and exception mapper. In my case I'm catching bad response from client through in-interceptor and then I would like abort the cxf bus chain and throw a fault. Unfortunately I couldn't do it, cause in every situation exception thrown from interceptor is being only logged, but the main error (wrong json format) is propagated to exception mapper. I would like to avoid Exception mapper, but I don't know how. I'm using WebClient to implement interceptors like this:

@Component
public class MyInterceptor extends AbstractPhaseInterceptor<Message> {

    public MyInterceptor() {
        super(POST_STREAM);
    }

    @Override
    public void handleMessage(Message message) throws Fault {
        if (message != null) {
                //message.getExchange().setOneWay(true);
                //message.getExchange().put(Exception.class, new MyException());
                //message.getInterceptorChain().abort();
                //message.setContent(Exception.class, new MyException());
                //Endpoint ep = message.getExchange().get(Endpoint.class);
                //message.getInterceptorChain().abort();
                //if (ep.getInFaultObserver() != null) {
                //    ep.getInFaultObserver().onMessage(message);
                //}
                //throw new WebApplicationException( new MyException());

                //message.setContent(Response.class, response);
                throw new Fault(new MyException());
            }
        } 

I read that I should implement jaxrs-filter cause exceptions thrown by interceptor are not propagated to exception mapper. Is it any way to do that in java thanks to WebClient implementation?

S client = create(url, clazz, list(jsonProvider(), providers));
WebClient.getConfig(client).getInInterceptors().add(new MyInterceptor());

I've also tried to use different phases on interceptor, but it also didn't work.

Answer 1

I have been researching and testing with your issue. The problem is that the exceptions thrown from the CXF interceptors escape the JAX-RS flow ( see the answer of CXF team)

A Fault generated from interceptor can be catched implementing handleFault in the interceptor itself

 public void handleFault(Message message) {
       Exception e = message.getContent(Exception.class);
 }

Or implementing a FaultListener and registering it at CXF Bus

WebClient.getConfig(client).getBus().getProperties().put("org.apache.cxf.logging.FaultListener",new MyFaultListener());

public class MyFaultListener implements FaultListener{
    public boolean faultOccurred(final Exception exception,final String description,final Message message) {
        //return false to avoid warning of default CXF logging interceptor
        return false;
    }
}

But you can not return custom response from interceptor or respond a Fault to client.

The workaround I have found to achieve the desired behaviour consist in replacing the Response with a custom object that could be processed by your usual method invokation, like an exceptionMapper See CXF/ JAX-RS : Return Custom response from interceptor

Into Interceptor.handleMessage check the conditions you need and create a Response with custom status and entity. After this, stop the chain

public class MyInterceptor extends AbstractPhaseInterceptor<Message> {

    public MyInterceptor() {
        super(Phase.POST_STREAM);
    }

    @Override
    public void handleMessage(Message message) throws Fault {
        if (message != null) {
            //check the condition to raise the error 
            //build the custom Response replacing service call
            Response response = Response
                    .status(Response.Status.BAD_REQUEST)
                    .entity("custom error")
                    .build();
            message.getExchange().put(Response.class, response);

            //abort interceptor chain in you want to stop processing or throw a Fault (catched by handleFault)
            //message.getInterceptorChain().abort();
            //throw new Fault (new MyException());

        }

    public void handleFault(Message messageParam) {
    }
}

Add the ResponseExceptionMapper as provider when creating the JAXRS client

providers.add(new ResponseExceptionMapper<WebApplicationException>() {

    @Override
    public WebApplicationException fromResponse(Response r) {
        return new WebApplicationException(r);
    }

});

YourService proxy = JAXRSClientFactory.create(url, clazz,providers);
Client client = WebClient.client(proxy);
WebClient.getConfig(client).getInInterceptors().add(new MyInterceptor());

After this, a call to proxy.yourService() will raise a WebApplicationException if acomplish the interceptor check. You can catch it or rethrow in the desired way

try{
    proxy.yourService();
}catch (WebApplicationException e){
}

Hope this helps

Answer 2

I fully agree with previous answer. My implementation looks like:

@Component
public class ServiceFailureInterceptor extends AbstractPhaseInterceptor<Message> {

    private static final Logger LOG = LoggerFactory.getLogger(ServiceFailureInterceptor.class);

    public ServiceFailureInterceptor() {
        super(PRE_STREAM);
    }

    @Override
    public void handleMessage(Message message) {
        if (message != null) {
            int responseCode = (int) message.get(Message.RESPONSE_CODE);
                LogicException logicException = ErrorMapper.HTTP_STATUS_CODE_MAPPER.get(responseCode);
                InputStream is = b2stream(MapperUtils.json().toBytes(logicException));

                // clear old message & exchange
                Exchange exchange = message.getExchange();
                for (Class<?> contentFormat : message.getContentFormats()) {
                    message.setContent(contentFormat, null);
                }

                resetOrigInterceptorChain(message);
                resetFault(exchange);

                message.setContent(InputStream.class, is);
                Message outMessage = createOutMessage(exchange, is);
                prepareMessage(outMessage);
                prepareMessage(message);
        }
    }

    private void prepareMessage(Message message) {
        message.put(Message.REQUESTOR_ROLE, true);
        message.put(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON);
    }


    private Message createOutMessage(Exchange exchange, InputStream logicException) {
        Endpoint ep = exchange.get(Endpoint.class);
        Message outMessage = ep != null ? ep.getBinding().createMessage() : new MessageImpl();
        outMessage.setContent(InputStream.class, logicException);
        exchange.setOutMessage(outMessage);
        outMessage.setExchange(exchange);
        return outMessage;
    }

    private void resetFault(Exchange exchange) {
        exchange.put(Exception.class, null);
    }

    private void resetOrigInterceptorChain(Message message) {
        InterceptorChain chain = message.getInterceptorChain();
        if (chain != null) {
            for (Interceptor<?> interceptor : chain) {
                chain.remove(interceptor);
            }
            chain.reset();
        }
    }
}

After setting this exception manually I'm going to ExceptionMapper implementation where my LogicException is consumed and response with exception is building. I cannot avoid Exception mapper when is declared as a provider through WebClient, so I've decided to use it and remapped Exception later.