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Spring Integration: How to send messages from pubsub subscribers to external systems/servers with Http Methods

I have been trying to send messages to external systems(using rest template POST, PUT etc) from the service activators as below.
Below is my pubsub consumer class
public class MyConsumer{
#Autowired
ExternalService externalService;
#Bean
public PubSubInboundChannelAdapter messageChannelAdapter(final #Qualifier("myInputChannel") MessageChannel inputChannel,
PubSubTemplate pubSubTemplate)
{
PubSubInboundChannelAdapter adapter = new PubSubInboundChannelAdapter(pubSubTemplate, pubSubSubscriptionName);
adapter.setOutputChannel(inputChannel);
adapter.setAckMode(AckMode.AUTO_ACK);
adapter.setErrorChannelName("pubsubErrors");
return adapter;
}
#ServiceActivator(inputChannel = "pubsubErrors")
public void pubsubErrorHandler(Message<MessagingException> exceptionMessage) {
BasicAcknowledgeablePubsubMessage originalMessage = (BasicAcknowledgeablePubsubMessage) exceptionMessage
.getPayload().getFailedMessage().getHeaders().get(GcpPubSubHeaders.ORIGINAL_MESSAGE);
originalMessage.nack();
}
#Bean
public MessageChannel myInputChannel() {
return new DirectChannel();
}
#Bean
#ServiceActivator(inputChannel = "myInputChannel")
public MessageHandler messageReceiver_AddCustomer() {
return message -> {
externalService.postDataTOExternalSystems(new String((byte[]) message.getPayload());
};
}
#Bean
#ServiceActivator(inputChannel = "myInputChannel")
public MessageHandler messageReceiver_DeleteCustomer() {
return message -> {
externalService.deleteCustomer(new String((byte[]) message.getPayload());
BasicAcknowledgeablePubsubMessage originalMessage =
message.getHeaders().get(GcpPubSubHeaders.ORIGINAL_MESSAGE, BasicAcknowledgeablePubsubMessage.class);
originalMessage.ack();
};
}
}
ExternalService below is the service which sends data to the external systems.
public class ExternalService{
void postDataTOExternalSystems(Object obj){
// RequestEntity object formed with HttpEntity object using obj(in json) and headers
restTemplate.exchange("https://externalsystems/",HttpMethod.POST,requestEntity,Object.class);
}
void deleteDatafromExternalSystems(Object obj){
// RequestEntity object formed with HttpEntity object using obj(in json) and headers
restTemplate.exchange("https://externalsystems/",HttpMethod.Detele,requestEntity,Object.class);
}
}
Since both the methods messageReceiver_AddCustomer and messageReceiver_deleteCustomer are using same channel whats happening is when I try to just addcustomer, the deleteCustomer is also called by default.
I was thinking of creating a seperate channel for deleteCustomer, but creating in this way leads to creating channels for every usecase.
Hence would like to know three things here.
Is there is any other approach of sending through Spring integration through which I can send data to external systems using a single Channel or a different utilization of Channels.
If any error in the external service calls leads to unending of failure logs in the console
message_id: "6830962001745961"
publish_time {
seconds: 1675783352
nanos: 547000000
}
}, timestamp=1675783353720}]': error occurred in message handler

It's not clear what is your expectation for such a logic. You have two contradicting subscribers for the same input channel. It sounds more like you need a router first to determine where to proceed next with an input message from Pub/Sub: https://docs.spring.io/spring-integration/reference/html/message-routing.html#messaging-routing-chapter.
but creating in this way leads to creating channels for every usecase.
Sure! You can go without Spring Integration and just do everything with the plain if..else. So, what's a difference? Therefore I don't see a reasonable argument in your statement. Yo have different HTTP methods, and that is OK to map them via Spring Integration router to respective sub-flows. The MessageChannel is really first-class citizen in Spring Integration. It makes a solution as loosely-coupled as possible.
Several subscribers on your current DirectChannel will lead to a round-robin logic by default, so you'll be surprised that one message from Pub/Sub creates a customer, another deletes and so on in rounds. The PublishSubscribeChannel will make it bad as well: both of your subscribers are going to be called, so created first, then deleted immediately.

Can we use #RestClientTest when the rest template has interceptors using Spring boot 1.5.x?

I am using Spring Boot 1.5.x (Spring 4.2.x), and I created a RestClientSdk spring component class as shown here:
#Component
public class RestClientSdkImpl implements RestClientSdk {
private RestTemplate restTemplate;
#Autowired
public RestClientSdkImpl(RestTemplateBuilder restTemplateBuilder) {
this.restTemplate = restTemplateBuilder.build();
}
...
//other methods kept out for brevity
}
I have also defined a DefaultRestTemplateCustomizer spring component as shown here:
#Component
public class DefaultRestTemplateCustomizer implements RestTemplateCustomizer {
private LogClientHttpRequestInterceptor logClientHttpRequestInterceptor;
#Autowired
public DefaultRestTemplateCustomizer(LogClientHttpRequestInterceptor logClientHttpRequestInterceptor) {
this.logClientHttpRequestInterceptor = logClientHttpRequestInterceptor;
}
#Override
public void customize(RestTemplate restTemplate) {
restTemplate.getInterceptors().add(logClientHttpRequestInterceptor);
restTemplate.setRequestFactory(new BufferingClientHttpRequestFactory(new SimpleClientHttpRequestFactory()));
}
}
With that, I've defined a test class as shown below that uses the #RestClientTest annotation as shown below.
#RunWith(SpringRunner.class)
#RestClientTest(RestClientSdk.class)
#ActiveProfiles("test")
/*
* The RestClientTest only includes the most minimal configuration to include a rest template builder,
* so we include the rest sdk auto config within the scope of the test
*/
#ImportAutoConfiguration(RestSdkAutoConfiguration.class)
public class RestClientApplicationBehaviourTest{
#Autowired
private RestClientSdk restClientSdk;
#Autowired
private MockRestServiceServer mockRestServiceServer;
/**
* A simple Http Get that retrieves a JSON document from a rest server and
* produces a plain old java object as a response.
*/
#Test
public void testPlainHttpGet() throws IOException{
//ARRANGE
RestClientDto<?> simpleGetRequest = simpleHttpGet();
mockRestServiceServer.expect(once(), requestTo("http://localhost:8080/account/1234567890"))
.andRespond(withSuccess(IOUtils.getInputAsString("/stubs/account.json"),MediaType.APPLICATION_JSON));
//ACT
Account account = restClientSdk.send(simpleGetRequest, Account.class);
//ASSERT
mockRestServiceServer.verify();
Assert.assertNotNull(account);
Assert.assertNotNull(account.getAccountId());
Assert.assertNotNull(account.getFirstName());
Assert.assertNotNull(account.getLastName());
}
...
//not including other methods for brevity
}
PROBLEM
Because the MockRestServiceServer builder overrides the BufferingClientHttpRequestFactory in my rest template with a MockClientHttpRequestFactory, I am getting a null response from my body. This is because the logging interceptor is reading the input stream coming from the response and as such the stream no longer has content to read. The BufferingClientHttpRequestFactory would prevent that from happening. Now, I know that as of Spring 5.0.5, there is an extra option in the MockRestServiceServer builder called bufferContent, but I don't have the option of moving to Spring 5.x (Spring Boot 2.x), so I was wondering if there is a way to get this configured using Spring Boot 1.5.x / Spring 4.2.x.
I thank you in advance!
Juan

In order to workaround the issue, I needed to define a test configuration, that would allow me to override the client request factory. Please see the code below. It is a bit hacky, but I suppose the real solution here would be to upgrade to Spring 5.x / Spring Boot 2.x.
#Configuration
#Profile("test")
public class MockRestServiceServerConfiguration {
/**
* Wrap the Mock Rest client factory in the buffered one.
* #param restClientSdk The rest client SDK containing the rest template to use.
* #return The mock rest service server to use.
*/
#Bean
public MockRestServiceServer mockRestServiceServer(RestClientSdkImpl restClientSdkImpl) {
RestTemplate restTemplate = restClientSdkImpl.getRestTemplate();
MockRestServiceServer server = MockRestServiceServer.createServer(restTemplate);
//need to do this because getRequestFactory returns InterceptingHttpRequestFactory wraping the mock rest service server request factory
List<ClientHttpRequestInterceptor> templateInterceptors = restTemplate.getInterceptors();
restTemplate.setInterceptors(null);
//now we wrap the delegate, which should be the mock rest service server request factory
BufferingClientHttpRequestFactory bufferingFact = new BufferingClientHttpRequestFactory(restTemplate.getRequestFactory());
restTemplate.setRequestFactory(bufferingFact);
restTemplate.setInterceptors(templateInterceptors);
return server;
}
}

How to globally handle Spring WebSockets/Spring Messaging exception?

Question
Is there a way to globally handle Spring Messaging MessageDeliveryException caused by error (usualy insufficient authorities) in Spring WebSocket module?
Use case
I have implemented Spring WebSockets over STOMP to support ws connection in my webapp. To secure websocket endpoint I have created interceptor that authorizes user to start STOMP session at STOMP CONNECT time (as suggested in Spring documentation here in 22.4.11 section):
#Component
public class StompMessagingInterceptor extends ChannelInterceptorAdapter {
// Some code not important to the problem
#Override
public Message<?> preSend(Message<?> message, MessageChannel channel) {
StompHeaderAccessor headerAccessor = MessageHeaderAccessor.getAccessor(message, StompHeaderAccessor.class);
switch (headerAccessor.getCommand()) {
// Authenticate STOMP session on CONNECT using jwt token passed as a STOMP login header - it's working great
case CONNECT:
authorizeStompSession(headerAccessor);
break;
}
// Returns processed message
return message;
}
// Another part of code not important for the problem
}
and included spring-security-messaging configuration to add some fine-grained control over authorities when messaging:
#Configuration
public class WebSocketSecurityConfig extends AbstractSecurityWebSocketMessageBrokerConfigurer {
#Override
protected void configureInbound(MessageSecurityMetadataSourceRegistry messages) {
messages
.simpTypeMatchers(
SimpMessageType.CONNECT,
SimpMessageType.DISCONNECT,
SimpMessageType.HEARTBEAT
).authenticated()
.simpSubscribeDestMatchers("/queue/general").authenticated()
.simpSubscribeDestMatchers("/user/queue/priv").authenticated()
.simpDestMatchers("/app/general").authenticated()
.simpDestMatchers("/user/*/queue/priv").hasAuthority("ADMIN")
.anyMessage().denyAll();
}
#Override
protected boolean sameOriginDisabled() {
return true;
}
}
First of all - this configuration works as expected, the problem is when some security exception happens during websocket communication (say user without admin authority tries to send message on "/user/{something}/queue/priv" endpoint) it will end in org.springframework.messaging.MessageDeliveryException being rised and:
Full exception stack trace being written down to my server log
Returning STOMP ERROR frame containing part of stack trace as it's message field.
What I would like to do is catching (if possible globally) DeliveryException, checking what caused it and accoridingly to that create my own message for returning in STOMP ERROR frame (lets say with some error code like just 403 to mimic HTTP) and instead of throwing original exception further just logging some warning with my logger. Is it possible?
What I tried
When looking for solution I found some people using #MessageExceptionHandler to catch messaging exceptions, Spring 4.2.3 (which is version I use) documentation mentions it only once here in 25.4.11 section. I tried to use it like this:
#Controller
#ControllerAdvice
public class WebSocketGeneralController {
...
#MessageExceptionHandler
public WebSocketMessage handleException(org.springframework.messaging.MessageDeliveryException e) {
WebSocketMessage errorMessage = new WebSocketMessage();
errorMessage.setMessage(e.getClass().getName());
return errorMessage;
}
}
but it seems like method isn't called at any point (tried catching different exceptions, just Exception including - no results). What else should I look into?

#ControllerAdvice and #MessageExceptionHandler are working on business-logic level (like #MessageMapping or SimpMessagingTemplate).
To handle STOMP exceptions, you need to set STOMP error handler in STOMP registry:
#Configuration
#EnableWebSocketMessageBroker
class WebSocketConfiguration : WebSocketMessageBrokerConfigurer {
override fun configureMessageBroker(registry: MessageBrokerRegistry) {
// ...
}
override fun registerStompEndpoints(registry: StompEndpointRegistry) {
registry.addEndpoint("/ws")
// Handle exceptions in interceptors and Spring library itself.
// Will terminate a connection and send ERROR frame to the client.
registry.setErrorHandler(object : StompSubProtocolErrorHandler() {
override fun handleInternal(
errorHeaderAccessor: StompHeaderAccessor,
errorPayload: ByteArray,
cause: Throwable?,
clientHeaderAccessor: StompHeaderAccessor?
): Message<ByteArray> {
errorHeaderAccessor.message = null
val message = "..."
return MessageBuilder.createMessage(message.toByteArray(), errorHeaderAccessor.messageHeaders)
}
})
}
}

It does not work because of #ControllerAdvice catch exception from the request that passed dispatcher servlet. When you secure your endpoint and someone makes an unauthorized request it does not pass through dispatcher servlet. The request is caught by spring interceptors.

Spring Cloud Stream validation

How to perform validation with Spring Cloud Stream framework in message listeners using standard Spring annotation based validation?
Tried different cases, with #Valid #Payloadfor incoming object, tried method validation post processor with #Validated on entity, but it didn't help.
#StreamListener(MediaItemStream.ITEM_LIKED_CHANNEL)
public void handleLikeMessage(#Valid #Payload LikeInputDto like) {...
and
#Bean
public MethodValidationPostProcessor methodValidationPostProcessor() {
return new MethodValidationPostProcessor();
}
The best approach for now is just using of custom service for validation, but it looks not as wanted..
#Log4j2
#Service
#AllArgsConstructor
public class LikeStreamHandler {
private MediaEventMessagingService mediaEventMessagingService;
private ValidationService validationService;
#StreamListener(MediaItemStream.ITEM_LIKED_CHANNEL)
public void handleLikeMessage(LikeInputDto like) {
validationService.validate(like);
log.debug("Handling LIKE message: {}", like);
mediaEventMessagingService.processLikeEvent(like);
}
}

This is a new Feature of Spring Cloud Stream v2.1.0: Issue on GitHub: "Add (javax.)Validation Support for Stream Listener"

Spring Cloud Feign Interceptor

I have created a ClientHttpRequestInterceptor that I use to intercept all outgoing RestTemplate requests and responses. I would like to add the interceptor to all outgoing Feign requests/responses. Is there a way to do this?
I know that there is a feign.RequestInterceptor but with this I can only intercept the request and not the response.
There is a class FeignConfiguration that I found in Github that has the ability to add interceptors but I don't know in which maven dependency version it is.

A practical example of how to intercept the response in a Spring Cloud OpenFeign.
Create a custom Client by extending Client.Default as shown below:
public class CustomFeignClient extends Client.Default {
public CustomFeignClient(SSLSocketFactory sslContextFactory, HostnameVerifier hostnameVerifier) {
super(sslContextFactory, hostnameVerifier);
}
#Override
public Response execute(Request request, Request.Options options) throws IOException {
Response response = super.execute(request, options);
InputStream bodyStream = response.body().asInputStream();
String responseBody = StreamUtils.copyToString(bodyStream, StandardCharsets.UTF_8);
//TODO do whatever you want with the responseBody - parse and modify it
return response.toBuilder().body(responseBody, StandardCharsets.UTF_8).build();
}
}
Then use the custom Client in a configuration class:
public class FeignClientConfig {
public FeignClientConfig() { }
#Bean
public Client client() {
return new CustomFeignClient(null, null);
}
}
Finally, use the configuration class in a FeignClient:
#FeignClient(name = "api-client", url = "${api.base-url}", configuration = FeignClientConfig.class)
public interface ApiClient {
}
Good luck

If you want to use feign from spring cloud, use org.springframework.cloud:spring-cloud-starter-feign as your dependency coordinates. Currently the only way to modify the response is to implement your own feign.Client.