Heron is designed to be fully backward compatible with existing Apache Storm projects, which means that you can migrate an existing Storm topology to Heron by making just a few adjustments to the topology’s pom.xml Maven configuration file.

Step 1 — Download Heron API binaries with an installation script

Go to the releases page for Heron and download the appropriate installation script for your platform. The name of the script has this form:

  • heron-api-install-0.14.9-PLATFORM.sh

The script for Mac OS X (darwin), for example, would be named heron-api-install-0.14.9-darwin.sh.

Once the script is downloaded, run it while setting the --user and --maven flags:

$ chmod +x heron-api-install-0.14.9-PLATFORM.sh
$ ./heron-api-install-0.14.9-PLATFORM.sh --user --maven
Heron API installer
-------------------

Installing jars to local maven repo.
tar xfz /var/folders/8r/x6dwcnkn4p9_rgwvq_3jg6y00000gn/T/heron.XXXX.EnJDpZNb/heron-api.tar.gz
-C /var/folders/8r/x6dwcnkn4p9_rgwvq_3jg6y00000gn/T/heron.XXXX.EnJDpZNb

Heron API is now installed!

See http://heronstreaming.io/docs/getting-started for how to use Heron.

heron.build.version : '0.14.9'
heron.build.time : ...
heron.build.timestamp : ...
heron.build.host : ${HOSTNAME}
heron.build.user : ${USERNAME}
heron.build.git.revision : ...
heron.build.git.status : Clean

The Heron API will now be installed in your local Maven repository:

$ ls ~/.m2/repository/com/twitter/heron
heron-api
heron-spi
heron-storm

Step 2 — Add Heron dependencies to pom.xml

Copy the pom.xml segments below and paste them into your existing Storm pom.xml file in the dependencies block.

<dependency>
  <groupId>com.twitter.heron</groupId>
  <artifactId>heron-api</artifactId>
  <version>SNAPSHOT</version>
  <scope>compile</scope>
</dependency>
<dependency>
  <groupId>com.twitter.heron</groupId>
  <artifactId>heron-storm</artifactId>
  <version>SNAPSHOT</version>
  <scope>compile</scope>
</dependency>

Step 3 — Remove Storm dependencies from pom.xml

Delete the Storm dependency, which looks like this:

<dependency>
  <groupId>org.apache.storm</groupId>
  <artifactId>storm-core</artifactId>
  <version>storm-VERSION</version>
  <scope>provided</scope>
</dependency>

Step 4 (if needed) — Remove the Clojure plugin from pom.xml

Delete the Clojure plugin, which should look like this:

<plugin>
  <groupId>com.theoryinpractise</groupId>
  <artifactId>clojure-maven-plugin</artifactId>
  <version>1.3.12</version>
  <extensions>true</extensions>
  <configuration>
    <sourceDirectories>
      <sourceDirectory>src/clj</sourceDirectory>
    </sourceDirectories>
  </configuration>
</plugin>

Step 5 — Run Maven commands

Run the following Maven lifecycle commands:

$ mvn clean
$ mvn compile
$ mvn package

Note: Storm Distribute RPC is deprecated in Heron.

Step 5 (optional) — Launch your upgraded Heron topology

You can launch the compiled Maven project on your local cluster using heron submit.

First, modify your project’s base directory {basedir} and {PATH-TO-PROJECT}.jar, which is located in ${basedir}/target by Maven convention. Then modify the TOPOLOGY-FILE-NAME and TOPOLOGY-CLASS-NAME for your project:

$ heron submit local \
  ${basedir}/target/PATH-TO-PROJECT.jar \
  TOPOLOGY-FILE-NAME \
  TOPOLOGY-CLASS-NAME

Here’s an example submit command using the example topology from the Quick Start Guide guide:

$ heron submit local \
  ~/.heron/examples/heron-examples.jar \ # The path of the topology's jar file
  com.twitter.heron.examples.ExclamationTopology \ # The topology's Java class
  ExclamationTopology # The name of the topology

Next Steps