Welcome!

This repository includes several examples of performing streaming computation with Flink and storing result to C*.

Any comments, feedback or pull requests are welcome!

Motivation

A short description of the motivation behind the creation and maintenance of the project. As this project was created, as of Flink version 1.4.0, there are plenty streaming examples and a few simple C* connector examples. However, there are currently no concrete examples that demonstrates on storing streaming results to C* using flink-connector-cassandra library.

Included Examples

1. The streaming examples could be found at org.apache.flink.connectors.cassandra.streaming.
2. The associated CQL entity mapping is located at org.apache.flink.connectors.cassandra.datamodel

Examples Overview

Here is the quick overview for each examples

Name	Language Type	Computation Type	Data Type	CQL Entity
WikiAnalysis	Java	Streaming	POJO	WikiEditRecord
FileWordCount	Java	Streaming	Java Tuple	WordCount
FileWordCount	Java	Batch	Java Tuple	WordCount
SocketWindowWordCount	Java	Streaming	POJO	WordCount
SocketWindowWordCount	Java	Streaming	Java Tuple	WordCount
SocketWindowWordCount	Scala	Streaming	Scala Tuple	WordCount

Description

WikiAnalysis

org.apache.flink.connectors.cassandra.streaming.pojo.wiki.WikiAnalysis

An implementation to stream all edited record from Wikipedia to Flink and count the number of bytes that each user edits within a given window of time This example utilizes POJO data type to perform the stream computation and store the result back to C* with CQL entity WikiEditRecord

FileWordCount

1. Streaming example: org.apache.flink.connectors.cassandra.streaming.tuple.wordcount.FileWordCount
2. Batch example: org.apache.flink.connectors.cassandra.batch.tuple.wordcount.FileWordCount

A re-implementation of the "WordCount" program that computes a simple word occurrence histogram over text files in a streaming fashion. This example utilizes Tuple data type to perform the stream computation and store the result back to C* with CQL entity WordCount

SocketWindowWordCount

1. Java Pojo example: org.apache.flink.connectors.cassandra.streaming.pojo.wordcount.SocketWindowWordCount
2. Java Tuple example: org.apache.flink.connectors.cassandra.streaming.tuple.wordcount.SocketWindowWordCount
3. Scala Tuple example: org.apache.flink.connectors.cassandra.scala.streaming.tuple.wordcount.SocketWindowWordCount

An re-implementation to connects to a server socket, reads strings from the socket, perform word count against the text recieved and finally store the result back to C* with CQL entity WikiEditRecord. Several implementations exists, some for streaming over Java/Scala tuple data type, and the others for Java POJO type.

Common Services

Embedded Cassandra Service

A embedded C* service is provided that is convenient for testing and demonstration purposes. This embedded C* instance will live with JVM process and stores data at a directory created randomly upon bootstrap under /tmp.

Library Dependency

Here are the foundemental libraries used in this project, and those information could also be found in pom.xml

1. Apache Flink - Version 1.4.0
2. Apache Cassandra - Version 2.2.5
3. DataStax Java Driver - Version 3.0.0

How to Build Examples

Type the following maven command in console shell

1. mvn clean package for an executable fat-jar, or
2. mvn clean package -Pbuild-jar for an executable uber jar with cleaner dependencies.

Acknowledgement

This project is based on the QuickStart Project from Apache Flink Guide, in which most of libraries dependencies and Maven settings remain. In addition, most of the examples could also be found from Apache Flink project (without storing the result to C* sink, of course).