Slides from the tutorial workshop on custom extension development for Apache NiFi. This presentation accompanies the GitHub repository: https://github.com/apiri/nifi-mission-to-nars-workshop

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Mission to NARs with
Apache NiFi
Aldrin Piri - @aldrinpiri
ApacheCon Big Data 2016
12 May 2016

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Tutorial Resources
https://github.com/apiri/nifi-mission-to-nars-workshop

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Agenda
• Start with a dataflow… but we can do better!
• Do better with the NiFi Framework and custom processor
• Extension Points: Processors, Controller Services, Reporting Tasks
• Process Session & Process Context
• How the API ties to the NiFi repositories
• Testing isn’t that bad!
• Share with templates!

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Adding new functionality and development approach
 Extending the platform is about leveraging expansive Java ecosystem and existing code
– Make use of open source projects and provided libraries for targeted systems and services
– Reuse existing, proprietary or closed source libraries and wrap their functionality in the framework
 Test framework provides powerful means of testing extensions in isolation as they
would work in a live instance
 Deployment is as simple as copying the created NAR to your instance(s) lib directory

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Minimal Dependencies Needed
 Java Development Kit, version 1.7 or later
 Maven, version 3.1.0+

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Boilerplate Code is provided via Maven Archetype
 Support for creating bundles of major extension points of Processors and Controller
Services
– Processor Bundle
– Controller Service Bundle

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What is a NAR?
– Bundles the developed code to provide
extensions and their dependencies
– Allows extension classloader isolation,
aiding in versioning issues that can be
pervasive in interacting with a wide variety
of systems, services, and formats
NAR == NiFi ARchive
Consider it to be an OSGi-lite package
NAR Bundle Structure

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How long does it take to create an extension?
 Incorporating functionality from an existing library
– Create a bundle
– Include a dependency to the library
– Design User Experience
• Properties – How can this extension be configured? What are valid values for user input?
• Relationships – How will data move to the next stage of its processing?
– Wrap the core classes of the library in the framework and implement onTrigger
• ProcessSession abstracts interactions with backing repositories and handles unit-of-work sessions
• ProcessContext allows accessing defined properties which the framework has validated
– Test
– Deploy
For the majority of cases, development time is measured in hours*

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How long does it really take to create an extension?
 Increased development effort may be needed for handling specific protocols
– Driven through manual management of sessions, when there are resources with their own
lifecycles beyond the sole onTrigger method
– Common for protocol “Listeners”
For the majority of cases, development time is still measured in hours

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Behind the Scenes

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Architecture

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NiFi Architecture – Repositories - Pass by reference
FlowFile Content Provenance
F1 C1 C1 P1 F1
BEFORE
AFTER
F2 C1 C1 P3 F2 – Clone (F1)
F1 C1 P2 F1 – Route
P1 F1 – Create

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NiFi Architecture – Repositories – Copy on Write
FlowFile Content Provenance
F1 C1 C1 P1 F1 - CREATE
BEFORE
AFTER
F1 C1
F1.1 C2 C2 (encrypted)
C1 (plaintext)
P2 F1.1 - MODIFY
P1 F1 - CREATE

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Quick (and dirty?) Prototyping

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Prototype Dataflows Using Existing Binaries/Applications
 ExecuteProcess – Acts as a source
processor, creating FlowFiles containing
data written to STDOUT by the target
application
 ExecuteStreamCommand – Provides
content of FlowFiles to an external
application via STDIN and creates
FlowFiles containing data written STDOUT
Processors allow making external calls to applications and programs outside of the JVM

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Increased Flexibility of Prototyping via Scripting Languages
 ExecuteScript– Acts as a source processor,
creating FlowFiles containing data from a
referenced Script
 InvokeScriptedProcessor – Provides access
to the core framework API for interacting
with NiFi like a native Java processor
Processors allow using JVM friendly interpreted languages

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Resources
Developer Guide
– http://nifi.apache.org/developer-guide.html
Apache NiFi Maven Archetypes
– https://cwiki.apache.org/confluence/display/NIFI/Maven+Proj
ects+for+Extensions
Mission to NARs with Apache NiFi sample bundle
– https://github.com/apiri/nifi-mission-to-nars-workshop

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Thanks for hanging out!