Writing Apache Apex Applications

  • Beginner's Guide to Apache Apex This document provides a comprehensive overview of Apex and is recommended for developers just starting out with Apex.
  • Building Your First Apache Apex Application This video has a hands-on demonstration of how to check out the source code repositories and build them, then run the maven archetype command to generate a new Apache Apex project, populate the project with Java source files for a new application, and finally, build and run the application -- all on a virtual machine running Linux with Apache Hadoop installed.
  • Learning Apache Apex Book and related blog Apache Apex in a Nutshell An instructional and example driven guide on how to build Apex applications for developers and hands-on enterprise architects. It will help identify use cases, the building blocks for solutions and the process of implementing and testing production ready Apex applications.
  • Writing an Apache Apex application A PDF document that frames a hands-on exercise of building a basic application; also includes a diagram illustrating the life-cycle of operators.
  • Examples This is part of the source repository for Apache Apex Malhar and contains a number of readily runnable applications that developers will find especially useful. They include the important IO connectors as well as typical processing patterns like a Twitter stream analyzer, computation of statistics (such as moving averages) from a live stream of stock transactions from Yahoo! Finance; and one that analyzes a synthetic stream of eruption event data for the Old Faithful geyser.
  • Top N Words Application Tutorial This document provides a detailed step-by-step description of how to build and run a word counting application with Apache Apex starting with setting up your development environment, progressing to building, running and monitoring the application, visualizing the output and concluding with some advanced features such as assessing operator memory requirements, partitioning, and debugging.
  • Sales Dimensions Application Tutorial Similar to the Top N Words application but covers dimensional computations on a simulated sales data stream.
  • More Example Applications Sample code for more IO connectors and specialized tutorials covering a variety of topics such as large key-value state management (HDHT), custom partitioning using stream codecs, etc.


  • Slideshare/ApacheApex Presentations from past meetup events and other talks covering Apache Apex introduction, feature deep dive, integration, customer use cases and more.
  • Next Gen Decision Making in < 2ms A video discussing CapitalOne's experience with Apache Apex and evaluation of competing technologies along with the slides.
  • Stream Processing with Apache Apex (video) and (slides) A broad overview slide deck covering topics such as windowing, static and dynamic partitioning, unification, fault tolerance, locality, monitoring, etc.
  • Fault Tolerance and Processing Semantics (video) and (slides) A webinar covering core Apache Apex features including checkpointing and fault tolerance with fast, incremental recovery via a buffer server which uses a publish-subscribe model for inter-operator data transport. A variety of failure scenarios and processing guarantees are discussed.
  • Smart Partitioning with Apache Apex (video) and (slides) Webinar covering partitioning, including unique Apex features such as elasticity with dynamic resource allocation, parallel partitions for speculative execution and processing SLA etc.
  • Real Time Stream Processing Versus Batch Slide deck compares and contrasts the needs, use cases and challenges of stream processing with those of batch processing.


  • Introducing Apache Apex Introduces Apache Apex and discusses how it addresses the current challenges of Big Data in the areas of code reuse, operability, ease of use and the benefits of a YARN-native solution.
  • Tracing DAGs from Specification to Execution Discusses DAGs (Directed Acyclic Graphs) as an application model, how they can be specified in Java or via JSON, how the platform transforms them to physical plans for scaling and how they can be monitored via the REST API.
  • An Introduction to Checkpointing in Apache Apex Discusses checkpointing by saving serializing operator state to HDFS and how to configure the frequency of checkpointing (or skip it altogether) via attributes or annotations.
  • Operability — The Graveyard of Big Data Projects Argues that operability is a critical aspect of Big Data projects which implementors ignore at their peril. Features of Apache Apex that solve operability issues are discussed broadly.
  • End-to-end Exactly-Once with Apache Apex Details how Apache Apex can work in conjunction with transactional systems to provide exactly-once semantics. A simple example of reading data from a Kafka topic and writing processed results to a SQL database is discussed along with the relevant operators (already provided in the Apex Malhar library) and the importance of idempotency.
  • Dimensions Computation - Part 1: Introduction A two-part blog that discusses dimensions computation in Apache Apex in considerable detail. The first part introduces the domain, shows an AdEvent object to model tuples in the data stream and analyzes the various dimensions of interest.
  • Dimensions Computation - Part 2: Implementation The second part continues with discussion of the three phases involved (pre-aggregation, unification and storage) the JSON schema to encapsulate the various keys and aggregates, code fragments and, finally, concludes with visualization of the results.
  • Apache Apex Performance Benchmarks Discusses the performance suite used to certify releases.
  • Apache Software Foundation Discusses the history of the foundation, guiding principles, current statistics and provides numerous additional links for details of how the foundation operates and is managed.
  • Data Ingestion Platform - Xavient Information Systems Discusses usage of Apache Apex in their data ingestion platform.


  • Troubleshooting Guide