Integration / Apache NiFi Interview Questions

What is a Processor in Apache NiFi and what are the main processor categories?

A Processor is the fundamental building block of a NiFi data flow. Each processor performs one specific operation on FlowFiles: fetching from a source, transforming content, routing on attributes, writing to a destination, and so on. Processors are connected via Connections to form a directed dataflow graph on the canvas.

NiFi ships with hundreds of built-in processors in functional categories:

Data Ingestion: GetFile, GetHTTP, GetSFTP, ListenHTTP, ConsumerKafka, GetSQS — pull or receive data from external sources.

Data Egress: PutFile, PublishKafka, PutS3Object, PostHTTP, PutEmail, PutSFTP — write or send data to destinations.

Routing and Mediation: RouteOnAttribute, RouteOnContent, SplitText, SplitJSON, MergeContent — split, merge, or direct FlowFiles to different paths.

Database Interaction: ExecuteSQL, PutDatabaseRecord, QueryDatabaseTable, GenerateTableFetch — read from and write to JDBC-accessible databases.

Attribute Extraction: UpdateAttribute, EvaluateJsonPath, ExtractText, LookupRecord — read or modify FlowFile attributes.

Transformation: ConvertRecord, JoltTransformJSON, TransformXml, ReplaceText — change format or content of payloads.

Custom processors can be developed in Java, packaged as NAR (NiFi Archive) files, and deployed to NiFi's lib directory.

Take quiz

Which processor routes FlowFiles to different downstream connections based on attribute values?SplitText

✗ Try again — SplitText splits content into multiple FlowFiles; it does not route by attribute.

RouteOnAttribute

✓ Well done — RouteOnAttribute evaluates NiFi Expression Language conditions against attributes and routes accordingly.

UpdateAttribute

✗ Try again — UpdateAttribute modifies attributes but does not route FlowFiles.

What file format packages custom NiFi processors with classloader-isolated dependencies for deployment?JAR

✗ Try again — plain JARs are not the NiFi extension format.

WAR

✗ Try again — WAR is a Java web application archive, not a NiFi extension format.

NAR (NiFi Archive)

✓ Well done — NAR files provide classloader isolation, preventing dependency conflicts between processors.

More Related questions...

What is Apache NiFi and what problem does it solve? What is a FlowFile in Apache NiFi? What are the three NiFi repositories and what does each store? What is a Processor in Apache NiFi and what are the main processor categories? What is a Connection in NiFi and how does back-pressure work? What is NiFi Expression Language and where can it be used? What is data provenance in Apache NiFi and how do you access it? What is a Process Group in NiFi and why is it used? What is NiFi Registry and how does it integrate with NiFi? How does NiFi clustering work and what is the role of ZooKeeper? What is a Controller Service in NiFi and how is it different from a Processor? What is the GenerateTableFetch and QueryDatabaseTable pattern for incremental database ingestion? What is the Record-based processing model in NiFi and why is it preferred? What is State Management in NiFi and what types of state scope exist? What is NiFi Site-to-Site (S2S) and when do you use it? What is NiFi and how does it relate to Apache NiFi? What is NiFi Parameter Context and how does it differ from Variables? How does NiFi handle security — TLS, authentication, and authorization? What is the NiFi NAR (NiFi Archive) classloading model? What are Reporting Tasks in NiFi and what are common use cases? How do you handle errors and failures in a NiFi flow? What is the SplitText processor and how do you control split behavior? What is the MergeContent processor and how is it used? What is the InvokeHTTP processor and what are key configuration considerations? What is the PublishKafka and ConsumeKafka processor pair and what are key configuration options? What is the ExecuteScript processor and what scripting languages does it support? What is the JoltTransformJSON processor and how do you use it? What is the PutDatabaseRecord processor and how does it differ from ExecuteSQL? What is the ListSFTP and FetchSFTP processor pattern and how does it work? What is the LookupRecord processor used for? What is the PartitionRecord processor and what is a common use case? What is the ConvertRecord processor and how is it used for format conversion? What are the NiFi processor scheduling strategies? What is the difference between EvaluateJsonPath and FlattenJson processors? How does NiFi integrate with Apache Hadoop and HDFS? What is the UpdateAttribute processor and how is its Advanced Mode used? How do you implement deduplication in a NiFi flow? What is the HandleHttpRequest and HandleHttpResponse processor pair used for? How does NiFi achieve guaranteed delivery and what are its durability guarantees? What is the Funnel component in NiFi and when do you use it? What is the difference between GetFile and ListFile + FetchFile processors? How does NiFi support schema evolution in data pipelines? What is the RouteText processor and how does it differ from RouteOnContent? What performance tuning options are available in NiFi and what are common bottleneck patterns? How does NiFi integrate with cloud storage services like Amazon S3?

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Integration / Apache NiFi Interview Questions

What is a Processor in Apache NiFi and what are the main processor categories?

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