[ 
https://issues.apache.org/jira/browse/CAMEL-14233?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Rafał Gała updated CAMEL-14233:
-------------------------------
    Description: 
When exchange aggregation is used, using GroupedExchangeAggregationStrategy for 
example:

 
{code:java}
from(..)
.process(some processor here that sets KafkaConstants.TOPIC header here)
.aggregate(new GroupedExchangeAggregationStrategy ())
.to(kafka:...)
{code}
it is not possible to override topic per exchange by using KafkaConstants.TOPIC 
header, because in *createRecord* of KafkaProducer class, the topic is chosen 
from header of aggregating Exchange which may not be set because it may have 
been set only on Exchanges that were aggregated. When creating ProducerRecord 
from Iterable, the topic should be chosen from header of each Exchange 
separately:
{code:java}
protected Iterator<ProducerRecord> createRecorder(Exchange exchange) throws 
Exception {
    String topic = endpoint.getConfiguration().getTopic();

    if (!endpoint.getConfiguration().isBridgeEndpoint()) {
        String headerTopic = exchange.getIn().getHeader(KafkaConstants.TOPIC, 
String.class);
        boolean allowHeader = true;

        // when we do not bridge then detect if we try to send back to ourselves
        // which we most likely do not want to do
        if (headerTopic != null && 
endpoint.getConfiguration().isCircularTopicDetection()) {
            Endpoint from = exchange.getFromEndpoint();
            if (from instanceof KafkaEndpoint) {
                String fromTopic = ((KafkaEndpoint) 
from).getConfiguration().getTopic();
                allowHeader = !headerTopic.equals(fromTopic);
                if (!allowHeader) {
                    log.debug("Circular topic detected from message header."
                            + " Cannot send to same topic as the message comes 
from: {}"
                            + ". Will use endpoint configured topic: {}", from, 
topic);
                }
            }
        }
        if (allowHeader && headerTopic != null) {
            topic = headerTopic;
        }
    }

    if (topic == null) {
        // if topic property was not received from configuration or header 
parameters take it from the remaining URI
        topic = URISupport.extractRemainderPath(new 
URI(endpoint.getEndpointUri()), true);
    }

...

    Object msg = exchange.getIn().getBody();

    // is the message body a list or something that contains multiple values
    Iterator<Object> iterator = null;
    if (msg instanceof Iterable) {
        iterator = ((Iterable<Object>) msg).iterator();
    } else if (msg instanceof Iterator) {
        iterator = (Iterator<Object>) msg;
    }
    if (iterator != null) {
        final Iterator<Object> msgList = iterator;

        final String msgTopic = topic;

        return new Iterator<ProducerRecord>() {
            @Override
            public boolean hasNext() {
                return msgList.hasNext();
            }

            @Override
            public ProducerRecord next() {

                // must convert each entry of the iterator into the value 
according to the serializer
                Object next = msgList.next();
                Object value = tryConvertToSerializedType(exchange, next, 
endpoint.getConfiguration().getSerializerClass());

                if (hasPartitionKey && hasMessageKey) {
                    return new ProducerRecord(msgTopic, partitionKey, null, 
key, value, propagatedHeaders);
                } else if (hasMessageKey) {
                    return new ProducerRecord(msgTopic, null, null, key, value, 
propagatedHeaders);
                } else {
                    return new ProducerRecord(msgTopic, null, null, null, 
value, propagatedHeaders);
                }
            }

            @Override
            public void remove() {
                msgList.remove();
            }
        };
    }

...
}

{code}
 

  was:
When exchange aggregation is used, using GroupedExchangeAggregationStrategy for 
example:

 
{code:java}
from(..)
.process(some processor here that sets KafkaConstants.TOPIC header here)
.aggregate(new GroupedExchangeAggregationStrategy ())
.to(kafka:...)
{code}
it is not possible to override topic per exchange by using KafkaConstants.TOPIC 
header, because in *createRecord* of KafkaProducer class, the topic is chosen 
from header of aggregating Exchange which may not be set because it may have 
been set only on Exchanges that were aggregated. When creating ProducerRecord 
from Iterable, the topic should be chosen from header of each Exchange 
separately:
{code:java}
protected Iterator<ProducerRecord> createRecorder(Exchange exchange) throws 
Exception {
    String topic = endpoint.getConfiguration().getTopic();

    if (!endpoint.getConfiguration().isBridgeEndpoint()) {
        String headerTopic = exchange.getIn().getHeader(KafkaConstants.TOPIC, 
String.class);
        boolean allowHeader = true;

        // when we do not bridge then detect if we try to send back to ourselves
        // which we most likely do not want to do
        if (headerTopic != null && 
endpoint.getConfiguration().isCircularTopicDetection()) {
            Endpoint from = exchange.getFromEndpoint();
            if (from instanceof KafkaEndpoint) {
                String fromTopic = ((KafkaEndpoint) 
from).getConfiguration().getTopic();
                allowHeader = !headerTopic.equals(fromTopic);
                if (!allowHeader) {
                    log.debug("Circular topic detected from message header."
                            + " Cannot send to same topic as the message comes 
from: {}"
                            + ". Will use endpoint configured topic: {}", from, 
topic);
                }
            }
        }
        if (allowHeader && headerTopic != null) {
            topic = headerTopic;
        }
    }

    if (topic == null) {
        // if topic property was not received from configuration or header 
parameters take it from the remaining URI
        topic = URISupport.extractRemainderPath(new 
URI(endpoint.getEndpointUri()), true);
    }

...

    Object msg = exchange.getIn().getBody();

    // is the message body a list or something that contains multiple values
    Iterator<Object> iterator = null;
    if (msg instanceof Iterable) {
        iterator = ((Iterable<Object>) msg).iterator();
    } else if (msg instanceof Iterator) {
        iterator = (Iterator<Object>) msg;
    }
    if (iterator != null) {
        final Iterator<Object> msgList = iterator;

        final String msgTopic = topic;

        return new Iterator<ProducerRecord>() {
            @Override
            public boolean hasNext() {
                return msgList.hasNext();
            }

            @Override
            public ProducerRecord next() {
{code}
Maybe this is a good place, to make 
{code{
                // must convert each entry of the iterator into the value 
according to the serializer
                Object next = msgList.next();
                Object value = tryConvertToSerializedType(exchange, next, 
endpoint.getConfiguration().getSerializerClass());

                if (hasPartitionKey && hasMessageKey) {
                    return new ProducerRecord(msgTopic, partitionKey, null, 
key, value, propagatedHeaders);
                } else if (hasMessageKey) {
                    return new ProducerRecord(msgTopic, null, null, key, value, 
propagatedHeaders);
                } else {
                    return new ProducerRecord(msgTopic, null, null, null, 
value, propagatedHeaders);
                }
            }

            @Override
            public void remove() {
                msgList.remove();
            }
        };
    }

...
}

{code}
 


> camel-kafka - topic overriding not possible when using aggregation
> ------------------------------------------------------------------
>
>                 Key: CAMEL-14233
>                 URL: https://issues.apache.org/jira/browse/CAMEL-14233
>             Project: Camel
>          Issue Type: Bug
>          Components: camel-kafka
>    Affects Versions: 2.24.2
>            Reporter: Rafał Gała
>            Priority: Major
>
> When exchange aggregation is used, using GroupedExchangeAggregationStrategy 
> for example:
>  
> {code:java}
> from(..)
> .process(some processor here that sets KafkaConstants.TOPIC header here)
> .aggregate(new GroupedExchangeAggregationStrategy ())
> .to(kafka:...)
> {code}
> it is not possible to override topic per exchange by using 
> KafkaConstants.TOPIC header, because in *createRecord* of KafkaProducer 
> class, the topic is chosen from header of aggregating Exchange which may not 
> be set because it may have been set only on Exchanges that were aggregated. 
> When creating ProducerRecord from Iterable, the topic should be chosen from 
> header of each Exchange separately:
> {code:java}
> protected Iterator<ProducerRecord> createRecorder(Exchange exchange) throws 
> Exception {
>     String topic = endpoint.getConfiguration().getTopic();
>     if (!endpoint.getConfiguration().isBridgeEndpoint()) {
>         String headerTopic = exchange.getIn().getHeader(KafkaConstants.TOPIC, 
> String.class);
>         boolean allowHeader = true;
>         // when we do not bridge then detect if we try to send back to 
> ourselves
>         // which we most likely do not want to do
>         if (headerTopic != null && 
> endpoint.getConfiguration().isCircularTopicDetection()) {
>             Endpoint from = exchange.getFromEndpoint();
>             if (from instanceof KafkaEndpoint) {
>                 String fromTopic = ((KafkaEndpoint) 
> from).getConfiguration().getTopic();
>                 allowHeader = !headerTopic.equals(fromTopic);
>                 if (!allowHeader) {
>                     log.debug("Circular topic detected from message header."
>                             + " Cannot send to same topic as the message 
> comes from: {}"
>                             + ". Will use endpoint configured topic: {}", 
> from, topic);
>                 }
>             }
>         }
>         if (allowHeader && headerTopic != null) {
>             topic = headerTopic;
>         }
>     }
>     if (topic == null) {
>         // if topic property was not received from configuration or header 
> parameters take it from the remaining URI
>         topic = URISupport.extractRemainderPath(new 
> URI(endpoint.getEndpointUri()), true);
>     }
> ...
>     Object msg = exchange.getIn().getBody();
>     // is the message body a list or something that contains multiple values
>     Iterator<Object> iterator = null;
>     if (msg instanceof Iterable) {
>         iterator = ((Iterable<Object>) msg).iterator();
>     } else if (msg instanceof Iterator) {
>         iterator = (Iterator<Object>) msg;
>     }
>     if (iterator != null) {
>         final Iterator<Object> msgList = iterator;
>         final String msgTopic = topic;
>         return new Iterator<ProducerRecord>() {
>             @Override
>             public boolean hasNext() {
>                 return msgList.hasNext();
>             }
>             @Override
>             public ProducerRecord next() {
>                 // must convert each entry of the iterator into the value 
> according to the serializer
>                 Object next = msgList.next();
>                 Object value = tryConvertToSerializedType(exchange, next, 
> endpoint.getConfiguration().getSerializerClass());
>                 if (hasPartitionKey && hasMessageKey) {
>                     return new ProducerRecord(msgTopic, partitionKey, null, 
> key, value, propagatedHeaders);
>                 } else if (hasMessageKey) {
>                     return new ProducerRecord(msgTopic, null, null, key, 
> value, propagatedHeaders);
>                 } else {
>                     return new ProducerRecord(msgTopic, null, null, null, 
> value, propagatedHeaders);
>                 }
>             }
>             @Override
>             public void remove() {
>                 msgList.remove();
>             }
>         };
>     }
> ...
> }
> {code}
>  



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