Pulsar Functions Java Starter

This repo houses some example Pulsar Functions written in Java. These functions can all be run either in local mode or in cluster mode.

Requirements

You'll need to have Maven installed.

Setup

Pulsar Functions written in Java need to be packaged as a "fat" jar. To create a fat jar:

$ mvn package

To deploy and run the functions in this repo, you'll need to navigate to the Pulsar repo and use the pulsar-admin executable in the bin folder. We recommend setting the path to the jar file created in this repo as an environment variable:

$ export PULSAR_FUNCTIONS_JAR=`pwd`/target/pulsar-functions-0.1.0-SNAPSHOT-jar-with-dependencies.jar
$ cd /path/to/incubator-pulsar

# Example create command
$ bin/pulsar-admin functions create \
  --jar $PULSAR_FUNCTIONS_JAR \
  --className pulsarfunctions.starter.javanative.SimpleStringFunction \
  --inputs input_topic \
  --output output_topic

Included functions

The following example functions are included in this repo:

Function name	Description	API used
ExclamationFunction	Treats incoming message as string and appends exclamation('!') to it	Java native API
SimpleStringFunction	Ignores the input to the function and simply outputs the string "This is my function!" every time a message arrives	Java native API
CustomSerDeInputFunction	This function uses a custom serialization class for deserializing input message (TweetSerDe) to type Tweet objects	Java native API
CustomSerDeOutputFunction	This function uses a custom serialization class for serializing output message (TweetSerDe) from type Tweet objects	Java native API
LogFunction	This function uses the inbuilt sdk's functionality to route log messages to a log topic	Java SDK API
PublishFunction	This function uses the inbuilt sdk's functionality to publish messages to a specific topic	Java SDK API
UserConfigFunction	This function uses the inbuilt sdk's functionality to get command line parameters inside the function runtime	Java SDK API
WordCountFunction	This function uses the inbuilt sdk's state functionality to do word count	Java SDK API