How to read offset after delivering message using kafka outbound channel

Question

I am using kafka output channel adapter to send the messages.Is there any way to get the offset after delivering the message, below is my code

<int-kafka:outbound-channel-adapter id="kafkaCommonOutboundChannelAdapter"
                                        kafka-template="kafkaTemplate"
                                        header-mapper="kafkaHeaderMapper"
                                        auto-startup="true"
                                        topic-expression="headers['topic']"
                                        partition-id-expression="headers['partition']"
                                        sync="true">
        <int-kafka:request-handler-advice-chain>
            <ref bean="requestHandlerAdvice"/>
            <ref bean="retryAdvice"/>
        </int-kafka:request-handler-advice-chain>
    </int-kafka:outbound-channel-adapter>


  <bean id="requestHandlerAdvice"
      class="org.springframework.integration.handler.advice.ExpressionEvaluatingRequestHandlerAdvice">
    <property name="trapException" value="true"/>
    <property name="onSuccessExpression" ref="success"/>
    <property name="successChannelName" value="successChannel"/>
    <property name="onFailureExpression" ref="failure"/>
    <property name="failureChannelName" value="failureChannel"/>
</bean>

Thanks

Answer 1

The KafkaProducerMessageHandler comes with an option like:

/**
 * Set the success channel.
 * @param sendSuccessChannel the Success channel.
 */
public void setSendSuccessChannel(MessageChannel sendSuccessChannel) {

which is used in the end after successful production:

processSendResult(message, producerRecord, sendFuture, getSendSuccessChannel());

and does this:

                if (metadataChannel != null) {
                    KafkaProducerMessageHandler.this.messagingTemplate.send(metadataChannel,
                            getMessageBuilderFactory()
                                    .fromMessage(message)
                                    .setHeader(KafkaHeaders.RECORD_METADATA, sendResult.getRecordMetadata())
                                    .build());
                }

Pay attention to that KafkaHeaders.RECORD_METADATA where you can get access to the offset via RecordMetadata object.

See respective XML attribute:

    <xsd:attribute name="send-success-channel" type="xsd:string">
        <xsd:annotation>
            <xsd:documentation><![CDATA[
                Specifies the channel to which message with a payload of type
                'org.apache.kafka.clients.producer.RecordMetadata' will be sent
                after a successful send.
            ]]></xsd:documentation>
            <xsd:appinfo>
                <tool:annotation kind="ref">
                    <tool:expected-type type="org.springframework.messaging.MessageChannel" />
                </tool:annotation>
            </xsd:appinfo>
        </xsd:annotation>
    </xsd:attribute>