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Open source Java projects: Storm

Parallel realtime computation for unbounded data streams

By Steven Haines, JavaWorld.com, 12/05/12

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Page 6 of 7

After creating the topology, the PrimeNumberTopology class creates the infrastructure to execute the topology in local mode. In creates a LocalCluster object, passes a default Config object and the constructed Topology object to the submitTopology() method. This example, the topology "test," uses Util.sleep() to sleep for 10 seconds, then kills the topology and shuts down the LocalCluster. (In the next section we'll look at how to deploy such a topology to a real Storm cluster.

Building the project

Listing 4 shows the Maven pom.xml file for building this project.

Listing 4. pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.geekcap</groupId>
    <artifactId>storm-test</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>storm-test</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.0.2</version>
                <configuration>
                    <source>1.6</source>
                    <target>1.6</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <configuration>
                    <archive>
                        <manifest>
                            <addClasspath>true</addClasspath>
                            <classpathPrefix>lib/</classpathPrefix>
                            <mainClass>com.geekcap.storm.PrimeNumberTopology</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-dependency-plugin</artifactId>
                <executions>
                    <execution>
                        <id>copy</id>
                        <phase>install</phase>
                        <goals>
                            <goal>copy-dependencies</goal>
                        </goals>
                        <configuration>
                            <outputDirectory>${project.build.directory}/lib</outputDirectory>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>storm</groupId>
            <artifactId>storm-lib</artifactId>
            <version>0.8.1</version>
            <!-- keep storm out of the jar-with-dependencies
               <scope>provided</scope> -->
        </dependency>
    </dependencies>

    <repositories>
        <repository>
            <id>github-releases</id>
            <url>http://oss.sonatype.org/content/repositories/github-releases/</url>
        </repository>
        <repository>
            <id>clojars.org</id>
            <url>http://clojars.org/repo</url>
        </repository>
    </repositories>
</project>

Some notables about the POM file:

  • maven-jar-plugin defines the main class for the .jar file, which is com.geekcap.storm.PrimeNumberTopology.
  • maven-dependency-plugin copies all dependencies to the target folder's lib directory.
  • The POM includes the storm-lib dependency. If you were building a distributed-mode application you would include storm rather than storm-lib.
  • The POM also includes the clojars.org Maven repository, which includes the storm-lib project. (Clojars is a community repository for open source Clojure libraries.)

You can build this project with mvn clean install and then execute the it with java -jar storm-test-1.0-SNAPSHOT.jar from the target directory. In my environment I see the following output:

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