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Learning Apache Apex
Learning Apache Apex

Learning Apache Apex: Real-time streaming applications with Apex

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Profile Icon Gundabattula Profile Icon Thomas Weise Profile Icon Munagala V. Ramanath Profile Icon David Yan Profile Icon Kenneth Knowles +1 more Show less
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Full star icon Full star icon Full star icon Full star icon Full star icon 5 (1 Ratings)
Paperback Nov 2017 290 pages 1st Edition
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$27.98 $39.99
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Arrow left icon
Profile Icon Gundabattula Profile Icon Thomas Weise Profile Icon Munagala V. Ramanath Profile Icon David Yan Profile Icon Kenneth Knowles +1 more Show less
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Paperback Nov 2017 290 pages 1st Edition
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$48.99
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Learning Apache Apex

Getting Started with Application Development

The previous chapter introduced concepts, use cases, and application model. This chapter will be about application development and guide the reader through the process of building and running their first application. The examples will be simple; more comprehensive applications will be covered in subsequent chapters.

In this chapter we will cover the following topics:

  • Development process and methodology
  • Setting up the development environment
  • Creating a new Maven project
  • Custom operator development
  • Testing within the IDE
  • Running application on the cluster

Development process and methodology

Development of an Apex application starts with mapping the functional specification to operators (smaller functional building blocks), which can then be composed into a DAG to collectively provide the functionality required for the use case.

This involves identifying the data sources, formats, transformations and sinks for the application, and finding matching operators from the Apex library (which will be covered in the next chapter). In most cases, the required connectors will be available from the library that support frequent sources, such as files and Kafka, along with many other external systems that are part of the Apache Big Data ecosystem.

With the comprehensive operator library and set of examples to cover frequently used I/O cases and transformations, it is often possible to assemble a preliminary end-to-end flow that covers a subset...

Setting up the development environment

Development of Apex applications requires a Java development environment with the following:

  • Java Development Kit (JDK): Apex applications are mostly written in Java, and Apex itself is implemented in Java. Other Java Virtual Machine (JVM) languages such as Scala can also be used, but this is outside the scope of this book.
  • Maven: Apex comes with a Maven Archetype to bootstrap new projects and the Apex project itself also uses Maven as build tool.

In addition to the above, it is recommended to have an IDE with Maven support such as IntelliJ or Eclipse. Apex provides code style settings for these IDEs that can optionally be used.

It is further recommended to have Git installed. Git is not required to build an application, but it is a convenient way to fetch the Apex source code and is especially useful for easily navigating the full operator...

Creating a new Maven project

Apex applications are packaged in a special ZIP file format that contains everything needed for an application to be launched on a cluster (dependency jars, configuration files, and so on). It is roughly comparable to the uber jar approach that some other frameworks employ, with the difference that dependencies in the Apex package remain as individual JAR files, rather than being flattened into a standard JAR.

More information about Apex application packages can be found at http://apex.apache.org/docs/apex/application_packages/#apache-apex-packages.

It would be a rather involved task to set up a new Maven project from scratch. The Apex application archetype simplifies the process of creating an application skeleton for the expected artifact structure. Here is an example of the Maven command to create an Apex application archetype:

mvn archetype:generate...

Application specifications

Let's start by transforming this placeholder application into an application that counts words – the Hello World equivalent for big data processing frameworks. The functionality is easy to understand and not very important, as our focus here is on the development process.

The full source code of the modified application is available at https://github.com/tweise/apex-samples/tree/master/wordcount. Here is the modified application assembly in Application.java:

@Override
public void populateDAG(DAG dag, Configuration conf)
{
LineByLineFileInputOperator lineReader = dag.addOperator("input",
new LineByLineFileInputOperator());
LineSplitter parser = dag.addOperator("parser", new LineSplitter());
UniqueCounter counter = dag.addOperator("counter", new UniqueCounter());
GenericFileOutputOperator...

Custom operator development

As our example application has the LineSplitter operator, which is not part of the Apex library, we will use it as an example to illustrate the process of developing a custom operator.

Splitting a line into words is, of course, a simple stateless operation. Connectors and stateful transformations will be more involved, and there are many examples in the Apex library to look at for this.

Here is the line splitter:

public class LineSplitter extends BaseOperator 
{ 
  // default pattern for word-separators 
  private static final Pattern nonWordDefault =    Pattern.compile
("[\\p{Punct}\\s]+"); private String nonWordStr; // configurable regex private transient Pattern nonWord; // compiled regex /** * Output port on which words from the current file are emitted */ public final transient DefaultOutputPort...

Development process and methodology


Development of an Apex application starts with mapping the functional specification to operators (smaller functional building blocks), which can then be composed into a DAG to collectively provide the functionality required for the use case.

This involves identifying the data sources, formats, transformations and sinks for the application, and finding matching operators from the Apex library (which will be covered in the next chapter). In most cases, the required connectors will be available from the library that support frequent sources, such as files and Kafka, along with many other external systems that are part of the Apache Big Data ecosystem.

With the comprehensive operator library and set of examples to cover frequently used I/O cases and transformations, it is often possible to assemble a preliminary end-to-end flow that covers a subset of the functionality quickly, before building out the complete business logic in detail.

Note

Examples that show...

Setting up the development environment


Development of Apex applications requires a Java development environment with the following:

  • Java Development Kit (JDK): Apex applications are mostly written in Java, and Apex itself is implemented in Java. Other Java Virtual Machine (JVM) languages such as Scala can also be used, but this is outside the scope of this book.
  • Maven: Apex comes with a Maven Archetype to bootstrap new projects and the Apex project itself also uses Maven as build tool.

In addition to the above, it is recommended to have an IDE with Maven support such as IntelliJ or Eclipse. Apex provides code style settings for these IDEs that can optionally be used.

It is further recommended to have Git installed. Git is not required to build an application, but it is a convenient way to fetch the Apex source code and is especially useful for easily navigating the full operator library (apex-malhar) project within the IDE when working on operator customizations.

Note

For the latest details on...

Creating a new Maven project


Apex applications are packaged in a special ZIP file format that contains everything needed for an application to be launched on a cluster (dependency jars, configuration files, and so on). It is roughly comparable to the uber jar approach that some other frameworks employ, with the difference that dependencies in the Apex package remain as individual JAR files, rather than being flattened into a standard JAR.

Note

More information about Apex application packages can be found at http://apex.apache.org/docs/apex/application_packages/#apache-apex-packages.

It would be a rather involved task to set up a new Maven project from scratch. The Apex application archetype simplifies the process of creating an application skeleton for the expected artifact structure. Here is an example of the Maven command to create an Apex application archetype:

mvn archetype:generate \
  -DarchetypeGroupId=org.apache.apex \
  -DarchetypeArtifactId=apex-app-archetype -DarchetypeVersion=RELEASE...

Application specifications


Let's start by transforming this placeholder application into an application that counts words – the Hello World equivalent for big data processing frameworks. The functionality is easy to understand and not very important, as our focus here is on the development process.

The full source code of the modified application is available at https://github.com/tweise/apex-samples/tree/master/wordcount. Here is the modified application assembly in Application.java:

@Override
   public void populateDAG(DAG dag, Configuration conf)
   {
    LineByLineFileInputOperator lineReader = dag.addOperator("input",
         new LineByLineFileInputOperator());
     LineSplitter parser = dag.addOperator("parser", new LineSplitter());
     UniqueCounter counter = dag.addOperator("counter", new UniqueCounter());
     GenericFileOutputOperator<Object> output = dag.addOperator("output",
         new GenericFileOutputOperator<>());
     output.setConverter(new ToStringConverter...

Custom operator development


As our example application has the LineSplitter operator, which is not part of the Apex library, we will use it as an example to illustrate the process of developing a custom operator.

Splitting a line into words is, of course, a simple stateless operation. Connectors and stateful transformations will be more involved, and there are many examples in the Apex library to look at for this.

Here is the line splitter:

public class LineSplitter extends BaseOperator 
{ 
  // default pattern for word-separators 
  private static final Pattern nonWordDefault =    Pattern.compile
    ("[\\p{Punct}\\s]+"); 
 
  private String nonWordStr;              // configurable regex 
  private transient Pattern nonWord;      // compiled regex 
 
  /** 
   * Output port on which words from the current file are emitted 
   */ 
  public final transient DefaultOutputPort<String> output = new 
    DefaultOutputPort<>(); 
 
  /** 
   * Input port on which lines from the current...
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Key benefits

  • Get a clear, practical approach to real-time data processing
  • Program Apache Apex streaming applications
  • This book shows you Apex integration with the open source Big Data ecosystem

Description

Apache Apex is a next-generation stream processing framework designed to operate on data at large scale, with minimum latency, maximum reliability, and strict correctness guarantees. Half of the book consists of Apex applications, showing you key aspects of data processing pipelines such as connectors for sources and sinks, and common data transformations. The other half of the book is evenly split into explaining the Apex framework, and tuning, testing, and scaling Apex applications. Much of our economic world depends on growing streams of data, such as social media feeds, financial records, data from mobile devices, sensors and machines (the Internet of Things - IoT). The projects in the book show how to process such streams to gain valuable, timely, and actionable insights. Traditional use cases, such as ETL, that currently consume a significant chunk of data engineering resources are also covered. The final chapter shows you future possibilities emerging in the streaming space, and how Apache Apex can contribute to it.

Who is this book for?

This book assumes knowledge of application development with Java and familiarity with distributed systems. Familiarity with other real-time streaming frameworks is not required, but some practical experience with other big data processing utilities might be helpful.

What you will learn

  • • Put together a functioning Apex application from scratch
  • • Scale an Apex application and configure it for optimal performance
  • • Understand how to deal with failures via the fault tolerance features of the platform
  • • Use Apex via other frameworks such as Beam
  • • Understand the DevOps implications of deploying Apex

Product Details

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Publication date, Length, Edition, Language, ISBN-13
Publication date : Nov 30, 2017
Length: 290 pages
Edition : 1st
Language : English
ISBN-13 : 9781788296403
Vendor :
Apache
Category :
Languages :

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Product Details

Publication date : Nov 30, 2017
Length: 290 pages
Edition : 1st
Language : English
ISBN-13 : 9781788296403
Vendor :
Apache
Category :
Languages :

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Table of Contents

10 Chapters
Introduction to Apex Chevron down icon Chevron up icon
Getting Started with Application Development Chevron down icon Chevron up icon
The Apex Library Chevron down icon Chevron up icon
Scalability, Low Latency, and Performance Chevron down icon Chevron up icon
Fault Tolerance and Reliability Chevron down icon Chevron up icon
Example Project – Real-Time Aggregation and Visualization Chevron down icon Chevron up icon
Example Project – Real-Time Ride Service Data Processing Chevron down icon Chevron up icon
Example Project – ETL Using SQL Chevron down icon Chevron up icon
Introduction to Apache Beam Chevron down icon Chevron up icon
The Future of Stream Processing Chevron down icon Chevron up icon

Customer reviews

Rating distribution
Full star icon Full star icon Full star icon Full star icon Full star icon 5
(1 Ratings)
5 star 100%
4 star 0%
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1 star 0%
H. kropp Dec 19, 2017
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Working in the field of stream data processing myself I was really impressed how well this book in general describes the current development. On the other hand I was impressed by the maturity and features Apache Apex provides.With quite a lot of examples the book provides the reader with a good starting ground for his or her own learnings and development with Apache Apex.This book is truly an example-driven guide, which I really enjoyed reading.
Amazon Verified review Amazon
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