● Key concepts: DAG, Operators, Ports● APIs for defining Applications, Operators● “Word Count” example DAG● Building Apache Apex from source code● Creating a sample application● Demo● Questions
Outline
● An Application is defined as Directed Acyclic Graph : DAG● Vertices of the DAG are computational units : Operators● Edges of the DAG are data tuples in-motion : Streams● Operator end-points for input , output : Ports● An Operator takes one or more input streams, performs computations & emits one or more output streams
○ Each operator is USER’s business logic, or built-in operator from our open source library○ Operator may have multiple instances that run in parallel
Application as a DAG
Typical application example
● MyApplication implements StreamingApplication○ Provide implementation for populateDAG○ Stitch the DAG
● SampleOperator extends BaseOperator○ Define input ports, output ports ○ Define process methods○ Optional : Define beginWindow, endWindow, setup,
teardown
APIs : Application, Operator
Operator workflow
● Data at Rest - Count occurrences of words in a file● Data in Motion - Emit counts at the end of the window● Another variation - Emit cumulative counts at the end of
every window.
Sample application
Apex Application DAGHDFSLOGS
Lines Counts
Defining DAG
Reader Parser Counter Output
Input Operator (Adapter)
Output Operator (Adapter)
Generic Operators
HDFSLOGS
• Java : 1.7.x• mvn : 3.0 + • git : 1.7 +• Apache hadoop : How to : Single node cluster • Apache Apex Core
• git clone [email protected]:apache/apex-core.git• cd apex-core/• git checkout master• mvn clean install -DskipTests
• Apache Apex Malhar• git clone [email protected]:apache/apex-malhar.git• cd apex-malhar/• git checkout master• mvn clean install -DskipTests
• DataTorrent RTS community edition
Building Apache Apex
● Apache Apex website - http://apex.apache.org/● Subscribe - http://apex.apache.org/community.html● Download - http://apex.apache.org/downloads.html● Youtube : subscribe DataTorrent● Meetup - http://www.meetup.com/topics/apache-apex● Twitter : follow @ApacheApex● Startup Program – Free Enterprise License for Startups,
Educational Institutions, Non-Profits
Resources
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