Integration / Apache NiFi Interview Questions

What is the PublishKafka and ConsumeKafka processor pair and what are key configuration options?

PublishKafka and ConsumeKafka (and their record-aware variants PublishKafkaRecord and ConsumeKafkaRecord) are NiFi's integration points with Apache Kafka.

ConsumeKafka: Subscribes to one or more Kafka topics using the Kafka consumer group protocol. Key properties include: Kafka Brokers (bootstrap servers), Topic Name(s) (EL-supported), Group ID (consumer group name), Offset Reset (earliest/latest for new consumer groups), Max Poll Records (how many records per poll), and Honor Transactions (whether to respect Kafka transactional producers). Each polled batch produces one FlowFile containing the message value.

PublishKafka: Produces messages to a Kafka topic. Key properties: Topic Name (static or EL-expression like ${kafka.topic} for per-FlowFile routing), Failure Strategy (Route to Failure vs Roll Back), Message Key Field (for keyed messages), Delivery Guarantee (Best Effort, Wait for Local Ack, Wait for Replication). With PublishKafkaRecord, NiFi reads records from the FlowFile and publishes one Kafka message per record.

Both processors require a KafkaClientService Controller Service in NiFi 2.x for SSL, SASL, and schema registry integration.

What PublishKafka Delivery Guarantee setting ensures a message is acknowledged by all in-sync replicas before success is confirmed?Best Effort

✗ Try again — Best Effort (acks=0) does not wait for any acknowledgment.

Wait for Local Acknowledgment

✗ Try again — local acknowledgment (acks=1) only confirms the leader received it, not the replicas.

Wait for Replication

✓ Well done — Wait for Replication (acks=all) ensures all in-sync replicas have persisted the message before NiFi considers the publish successful.

What is the key behavioral difference between ConsumeKafka and ConsumeKafkaRecord?ConsumeKafkaRecord parses the polled batch as structured records and exposes them as a NiFi record set; ConsumeKafka treats each message as an opaque byte FlowFile

✓ Well done — ConsumeKafkaRecord integrates with RecordReader and RecordWriter, enabling schema-aware, record-level processing of Kafka message content.

ConsumeKafkaRecord supports only JSON topics; ConsumeKafka supports all formats

✗ Try again — ConsumeKafkaRecord supports any format for which a RecordReader exists (JSON, Avro, CSV, Parquet, etc.).

ConsumeKafka is deprecated and should not be used in new flows

✗ Try again — ConsumeKafka remains valid for use cases where schema-level processing is not needed.

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Integration / Apache NiFi Interview Questions

What is the PublishKafka and ConsumeKafka processor pair and what are key configuration options?

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