Interview Questions.

Question 1. What Is Apache Nifi?

Answer :

NiFi is helpful in creating DataFlow. It means you may transfer records from one gadget to another device as well as system the statistics in among.

Question 2. What Is Nifi Flowfile?

Answer :

A FlowFile is a message or occasion records or user records, that's driven or created within the NiFi. A FlowFile has specifically  matters connected with it. Its content (Actual payload: Stream of bytes) and attributes. Attributes are key fee pairs attached to the content material (You can say metadata for the content material).

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Question three. What Is Relationship In Nifi Dataflow?

Answer :

When a processor finishes with processing of FlowFile. It can bring about Failure or Success or any other courting. And based totally on this relationship you could send records to the Downstream or next processor or mediated as a consequence.

Question four. What Is Reporting Task?

Answer :

A Reporting Task is a NiFi extension factor that is capable of reporting and reading NiFi's inner metrics for you to offer the data to external resources or file reputation statistics as announcements that appear immediately inside the NiFi User Interface.

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Question five. What Is A Nifi Processor?

Answer :

Processor is a major aspect inside the NiFi, that allows you to genuinely paintings at the FlowFile content material and allows in creating, sending, receiving, reworking routing, splitting, merging, and processing FlowFile.

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Question 6. Is There A Programming Language That Apache Nifi Supports?

Answer :

NiFi is applied in the Java programming language and permits extensions (processors, controller offerings, and reporting tasks) to be carried out in Java. In addition, NiFi supports processors that execute scripts written in Groovy, Jython, and several other popular scripting languages.

Question 7. How Do You Define Nifi Content Repository?

Answer :

As we referred to previously, contents aren't saved within the FlowFile. They are saved within the content repository and referenced via the FlowFile. This permits the contents of FlowFiles to be stored independently and successfully primarily based on the underlying storage mechanism.

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Question 8. What Is The Backpressure In Nifi System?

Answer :

Sometime what occurs that Producer system is quicker than purchaser gadget. Hence, the messages which might be fed on is slower. Hence, all of the messages (FlowFiles) which aren't being processed will continue to be within the connection buffer. However, you can limit the relationship backpressure size either based totally on number of FlowFiles or range of records size. If it reaches to defined limit, connection will deliver lower back stress to producer processor not run. Hence, no greater FlowFiles generated, till backpressure is reduced.

Question nine. What Is The Template In Nifi?

Answer :

Template is a re-usable workflow. Which you may import and export within the same or distinct NiFi times. It can save lot of time as opposed to growing Flow again and again whenever. Template is created as an xml document.

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Question 10. What Is The Bulleting And How It Helps In Nifi?

Answer :

If you need to realize if any problems occur in a dataflow. You can take a look at inside the logs for whatever interesting, it's far much more convenient to have notifications pop up at the display. If a Processor logs whatever as a WARNING or ERROR, we will see a "Bulletin Indicator" display up within the pinnacle-right-hand corner of the Processor.

This indicator looks like a sticky notice and might be proven for 5 minutes after the occasion happens. Hovering over the bulletin offers records approximately what passed off so that the user does no longer have to sift through log messages to locate it. If in a cluster, the bulletin may also indicate which node in the cluster emitted the bulletin. We also can change the log stage at which announcements will occur inside the Settings tab of the Configure dialog for a Processor.

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Question eleven. Do The Attributes Get Added To Content (actual Data) When Data Is Pulled By Nifi ?

Answer :

You can honestly add attributes on your FlowFiles at every time, that’s the entire factor of setting apart metadata from the real facts. Essentially, one FlowFile represents an object or a message moving thru NiFi. Each FlowFile contains a chunk of content, that's the actual bytes. You can then extract attributes from the content material, and save them in memory. You can then operate against the ones attributes in reminiscence, with out touching your content. By doing so you can shop lots of IO overhead, making the whole go with the flow management process extremely efficient.

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Question 12. What Happens, If You Have Stored A Password In A Dataflow And Create A Template Out Of It?

Answer :

Password is a sensitive belongings. Hence, whilst exporting the DataFlow as a template password could be dropped. As soon as you import the template in the same or exceptional NiFi machine.

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Question thirteen. How Does Nifi Support Huge Volume Of Payload In A Dataflow?

Answer :

Huge volume of facts can transit from DataFlow. As data movements through NiFi, a pointer to the records is being passed around, called a FlowFile. The content material of the FlowFile is only accessed as wished.

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Question 14. What Is A Nifi Custom Properties Registry?

Answer :

You can use to load custom key, fee pair you may use custom homes registry, which can be configure as (in nifi.Properties record)

nifi.Variable.Registry.Properties=/conf/nifi_registry

And you could placed key cost pairs in that record and you could use that residences in you NiFi processor the usage of expression language e.G. $OS , when you have configured that belongings in registry document.

Question 15. Does Nifi Works As A Master-slave Architecture?

Answer :

No, from NiFi 1.0 there's zero-master philosophy is considered. And each node within the NiFi cluster is the identical. NiFi cluster is managed by way of the Zookeeper. Apache ZooKeeper elects a single node because the Cluster Coordinator, and failover is handled robotically by means of ZooKeeper. All cluster nodes file heartbeat and status information to the Cluster Coordinator. The Cluster Coordinator is liable for disconnecting and connecting nodes. Additionally, every cluster has one Primary Node, additionally elected by ZooKeeper.

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