Kafka Transactional Producer - apache-kafka

Question

I am using Kafka 2 and I was going through the following link.
https://cwiki.apache.org/confluence/display/KAFKA/KIP-98+-+Exactly+Once+Delivery+and+Transactional+Messaging
Below is my sample code for Transactional producer.
My code:
public void runProducer(final int sendMessageCount) throws Exception {
final Producer<Long, String> producer = createProducer();
producer.initTransactions();
final long time = System.currentTimeMillis();
try {
producer.beginTransaction();
for (long index = time; index < (time + sendMessageCount); index++) {
final ProducerRecord<Long, String> record =
new ProducerRecord<>(TOPIC, index,
"Test " + index);
// send returns Future
producer.send(record).get();
}
producer.commitTransaction();
}
catch (ProducerFencedException | OutOfOrderSequenceException | AuthorizationException e) {
e.printStackTrace();
// We can't recover from these exceptions, so our only option is to close the producer and exit.
producer.close();
}
catch (final KafkaException e) {
e.printStackTrace();
// For all other exceptions, just abort the transaction and try again.
producer.abortTransaction();
}
finally {
producer.flush();
producer.close();
}
}
Questions:
Do we need to call endTransaction after commitTransaction ?
Do we need to call sendOffsetsToTransaction? What will happen if I don't include this?
How does it work when we deploy the same code to multiple servers with same transactionId? Do we need to have a separate transactionId for each instance? Say, machine1 crashes after beginTransaction() and after sending few records? How does machine2 with same transactionId recovers.
Machine1 is using transactionId "test" and it crashed after beginTransaction() and after producing few records. When the same instance comes up how does it resume the same transaction? We will actually again start from init & begin transaction.
How does it work for the same topic which was not involving in transaction and involving in transaction now? I am starting a new consumerGroup with transaction_committed, Will it read the messages which were committed before the transaction? Will the consumer with transaction_uncommitted see the messages which were aborted by transaction?