Heron is designed to be fully backwards 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. 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>0.17.0</version>
  <scope>compile</scope>
</dependency>
<dependency>
  <groupId>com.twitter.heron</groupId>
  <artifactId>heron-storm</artifactId>
  <version>0.17.0</version>
  <scope>compile</scope>
</dependency>

Step 2. 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 3 (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 4. Run Maven commands

Run the following Maven lifecycle commands:

$ mvn clean
$ mvn compile
$ mvn package

Storm Distribute RPC is deprecated in Heron.

Step 4 (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