Rafał Gała created CAMEL-14233:
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Summary: 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
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;
{code}
Here the topic should be taken from an aggregated Exchange KafkaConstants.TOPIC
header (it may be different for each from the collection)
{code:java}
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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