Spring Cloud Dataflow Type conversion not working

Question

I have a processor which transforms byte[] payloads into MyClass payloads:

@Slf4j
@EnableBinding(Processor.class)
public class MyDecoder {

    @ServiceActivator(inputChannel = Processor.INPUT, outputChannel = Processor.OUTPUT)
    public MyClass decode(final byte[] payload) {
        MyClass decoded = doStuff(payload);
        if (decoded != null) {
            log.info("Successfully decoded!");
        }

        return decoded;
    }
}

I tried creating the following DSL : some-source | my-decoder | some-sink and some-sink reports errors because it doesn't have MyClass class in the classLoader. This is expected behaviour.

I tried applying type conversion on my-decoder like: some-source | my-decoder --spring.cloud.stream.bindings.output.contentType=application/json | some-sink and I am getting the following errors in my-decoder log:

2017-01-20 21:45:17.278  INFO 9408 --- [afka-listener-2] com.example.MyDecoder  : Successfully decoded!
2017-01-20 21:45:18.441  INFO 9408 --- [afka-listener-2] com.example.MyDecoder  : Successfully decoded!
2017-01-20 21:45:20.512  INFO 9408 --- [afka-listener-2] com.example.MyDecoder  : Successfully decoded!
2017-01-20 21:45:20.515 ERROR 9408 --- [afka-listener-2] o.s.kafka.listener.LoggingErrorHandler   : Error while processing: ConsumerRecord(topic = example.some-source, partition = 0, offset = 1, key = null, value = [B@7dfad000)

org.springframework.messaging.MessageDeliveryException: failed to send Message to channel 'output'; nested exception is java.lang.IllegalArgumentException: payload must not be null
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:449) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:373) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:115) ~[spring-messaging-4.3.5.RELEASE.jar!/:4.3.5.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:45) ~[spring-messaging-4.3.5.RELEASE.jar!/:4.3.5.RELEASE]
    at org.springframework.messaging.core.AbstractMessageSendingTemplate.send(AbstractMessageSendingTemplate.java:105) ~[spring-messaging-4.3.5.RELEASE.jar!/:4.3.5.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutput(AbstractMessageProducingHandler.java:292) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.produceOutput(AbstractMessageProducingHandler.java:212) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutputs(AbstractMessageProducingHandler.java:129) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:115) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:127) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.dispatcher.AbstractDispatcher.tryOptimizedDispatch(AbstractDispatcher.java:116) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:148) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:121) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:89) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:423) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:373) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:115) ~[spring-messaging-4.3.5.RELEASE.jar!/:4.3.5.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:45) ~[spring-messaging-4.3.5.RELEASE.jar!/:4.3.5.RELEASE]
    at org.springframework.messaging.core.AbstractMessageSendingTemplate.send(AbstractMessageSendingTemplate.java:105) ~[spring-messaging-4.3.5.RELEASE.jar!/:4.3.5.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutput(AbstractMessageProducingHandler.java:292) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.produceOutput(AbstractMessageProducingHandler.java:212) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutputs(AbstractMessageProducingHandler.java:129) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:115) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:127) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.channel.FixedSubscriberChannel.send(FixedSubscriberChannel.java:70) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.channel.FixedSubscriberChannel.send(FixedSubscriberChannel.java:64) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:115) ~[spring-messaging-4.3.5.RELEASE.jar!/:4.3.5.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:45) ~[spring-messaging-4.3.5.RELEASE.jar!/:4.3.5.RELEASE]
    at org.springframework.messaging.core.AbstractMessageSendingTemplate.send(AbstractMessageSendingTemplate.java:105) ~[spring-messaging-4.3.5.RELEASE.jar!/:4.3.5.RELEASE]
    at org.springframework.integration.endpoint.MessageProducerSupport.sendMessage(MessageProducerSupport.java:171) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.kafka.inbound.KafkaMessageDrivenChannelAdapter.access$000(KafkaMessageDrivenChannelAdapter.java:47) ~[spring-integration-kafka-2.0.1.RELEASE.jar!/:na]
    at org.springframework.integration.kafka.inbound.KafkaMessageDrivenChannelAdapter$IntegrationMessageListener.onMessage(KafkaMessageDrivenChannelAdapter.java:197) ~[spring-integration-kafka-2.0.1.RELEASE.jar!/:na]
    at org.springframework.kafka.listener.adapter.RetryingAcknowledgingMessageListenerAdapter$1.doWithRetry(RetryingAcknowledgingMessageListenerAdapter.java:76) ~[spring-kafka-1.0.4.RELEASE.jar!/:na]
    at org.springframework.kafka.listener.adapter.RetryingAcknowledgingMessageListenerAdapter$1.doWithRetry(RetryingAcknowledgingMessageListenerAdapter.java:71) ~[spring-kafka-1.0.4.RELEASE.jar!/:na]
    at org.springframework.retry.support.RetryTemplate.doExecute(RetryTemplate.java:276) ~[spring-retry-1.1.5.RELEASE.jar!/:na]
    at org.springframework.retry.support.RetryTemplate.execute(RetryTemplate.java:172) ~[spring-retry-1.1.5.RELEASE.jar!/:na]
    at org.springframework.kafka.listener.adapter.RetryingAcknowledgingMessageListenerAdapter.onMessage(RetryingAcknowledgingMessageListenerAdapter.java:71) ~[spring-kafka-1.0.4.RELEASE.jar!/:na]
    at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.invokeListener(KafkaMessageListenerContainer.java:597) [spring-kafka-1.0.4.RELEASE.jar!/:na]
    at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.access$1800(KafkaMessageListenerContainer.java:222) [spring-kafka-1.0.4.RELEASE.jar!/:na]
    at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer$ListenerInvoker.run(KafkaMessageListenerContainer.java:778) [spring-kafka-1.0.4.RELEASE.jar!/:na]
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [na:1.8.0_111]
    at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_111]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_111]
Caused by: java.lang.IllegalArgumentException: payload must not be null
    at org.springframework.util.Assert.notNull(Assert.java:115) ~[spring-core-4.3.5.RELEASE.jar!/:4.3.5.RELEASE]
    at org.springframework.integration.support.MutableMessage.<init>(MutableMessage.java:57) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.support.MutableMessage.<init>(MutableMessage.java:53) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.support.MutableMessageBuilder.withPayload(MutableMessageBuilder.java:86) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.support.MutableMessageBuilderFactory.withPayload(MutableMessageBuilderFactory.java:35) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.support.MutableMessageBuilderFactory.withPayload(MutableMessageBuilderFactory.java:26) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.cloud.stream.binding.MessageConverterConfigurer$ContentTypeConvertingInterceptor.preSend(MessageConverterConfigurer.java:194) ~[spring-cloud-stream-1.1.0.RELEASE.jar!/:1.1.0.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel$ChannelInterceptorList.preSend(AbstractMessageChannel.java:538) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:415) ~[spring-integration-core-4.3.6.RELEASE.jar!/:4.3.6.RELEASE]
    ... 42 common frames omitted

I can see the message has been converted from byte[] to MyClass and is NOT null. I don't understand why I see the message 3 times before it fails because kafka property 'retries' is 0 as seen in the my-decoder log on start:

2017-01-20 21:44:32.080  INFO 9408 --- [           main] o.a.k.clients.producer.ProducerConfig    : ProducerConfig values: 
    compression.type = none
    metric.reporters = []
    metadata.max.age.ms = 300000
    metadata.fetch.timeout.ms = 60000
    reconnect.backoff.ms = 50
    sasl.kerberos.ticket.renew.window.factor = 0.8
    bootstrap.servers = [localhost:9092]
    retry.backoff.ms = 100
    sasl.kerberos.kinit.cmd = /usr/bin/kinit
    buffer.memory = 33554432
    timeout.ms = 30000
    key.serializer = class org.apache.kafka.common.serialization.ByteArraySerializer
    sasl.kerberos.service.name = null
    sasl.kerberos.ticket.renew.jitter = 0.05
    ssl.keystore.type = JKS
    ssl.trustmanager.algorithm = PKIX
    block.on.buffer.full = false
    ssl.key.password = null
    max.block.ms = 60000
    sasl.kerberos.min.time.before.relogin = 60000
    connections.max.idle.ms = 540000
    ssl.truststore.password = null
    max.in.flight.requests.per.connection = 5
    metrics.num.samples = 2
    client.id = 
    ssl.endpoint.identification.algorithm = null
    ssl.protocol = TLS
    request.timeout.ms = 30000
    ssl.provider = null
    ssl.enabled.protocols = [TLSv1.2, TLSv1.1, TLSv1]
    acks = 1
    batch.size = 16384
    ssl.keystore.location = null
    receive.buffer.bytes = 32768
    ssl.cipher.suites = null
    ssl.truststore.type = JKS
    security.protocol = PLAINTEXT
    retries = 0
    max.request.size = 1048576
    value.serializer = class org.apache.kafka.common.serialization.ByteArraySerializer
    ssl.truststore.location = null
    ssl.keystore.password = null
    ssl.keymanager.algorithm = SunX509
    metrics.sample.window.ms = 30000
    partitioner.class = class org.apache.kafka.clients.producer.internals.DefaultPartitioner
    send.buffer.bytes = 131072
    linger.ms = 0

I tried writing integration tests:

@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.NONE)
@DirtiesContext
public abstract class MyDecoderTests {

    @Autowired
    protected Processor channels;

    @Autowired
    protected MessageCollector collector;

    public static class UsingNothingIntegrationTests extends MyDecoderTest {

        @Test
        public void test() throws Exception {
            channels.input().send(new GenericMessage<Object>(Hex.decodeHex("ff".toCharArray())));
            assertThat(collector.forChannel(channels.output()), receivesPayloadThat(instanceOf(MyClass.class)));
        }
    }

    @SpringBootTest("spring.cloud.stream.bindings.output.contentType=application/json")
    public static class UsingOutputConverterIntegrationTests extends MyDecoderTest {

        @Test
        public void test() throws Exception {
            channels.input().send(new GenericMessage<Object>(Hex.decodeHex("ff".toCharArray())));
            assertThat(collector.forChannel(channels.output()), receivesPayloadThat(is("{\"example\": true\"}")));
        }
    }

    @Configuration
    @EnableAutoConfiguration
    @Import(MyDecoderConfiguration.class)
    public static class MyDecoderTestApplication {

    }
}

The tests run successfully, the conversion takes place.

Then, I thought my DSL isn't right so I wrote a new source to test with:

@Bean
@InboundChannelAdapter(Source.OUTPUT)
public MessageSource<MyClass> exampleSource() {
    return () -> new GenericMessage<>(getMyClassObject());
}

And the following DSL converts MyClass into JSON as expected: my-source --spring.cloud.stream.bindings.output.contentType=application/json | some-sink

Why am I getting the message about decoding logged 3 times and why is it failing with 'payload must not be null' message? Is it something with my processor?

Answer 1

You are seeing 3 attempts because that's the default retry configuration for the input channel in the binder.

There's a bug in the binder in that if the converter can't convert the message, it tries to create a message with a null payload.

The reason it can't convert the payload is because it sees the inbound content-type (presumably application/octet-stream) and it can't convert from that to JSON.

The work around is to add a file to the classpath:

META-INF/spring.integration.properties

and add

spring.integration.readOnly.headers=contentType

to it.

That prevents the propagation of the inbound content type header to the outbound message.

This requires spring integration 4.3.2 or higher.

In a future release of SCSt, this will be set by default.