HelloWorld - Gridify With Custom Task

Gridify With Custom Task Example

This example contains HelloWorld example that is using Gridify ^Javadoc annotation to grid-enable Java logic and also provides custom split and aggregate logic by deploying a custom task.

String 'Hello World' is passed as an argument to GridifyHelloWorldTaskExample.sayIt(String) method. Since this method is annotated with @Gridify ^Javadoc annotation it is automatically grid-enabled. The GridifyHelloWorldTask task specified in @Gridify ^Javadoc annotation will split the passed in string argument into words and send each word as job argument for execution on separate nodes. As an outcome, two participating nodes will print out a single word from 'Hello World' string. One node will print out word "Hello" and the other will print out word "World". If there is only one node participating, then it will print out both words.

Package:
org.gridgain.examples.helloworld.gridify.task

There are two classes implemented for this example:

GridifyHelloWorldTaskExample.java
GridifyHelloWorldTask.java

AspectJ AOP Configuration

We will use AspectJ AOP for this example. To use other AOP implementations (such as JBoss AOP, or Spring AOP), refer to AOP Configuration documentation.

The following configuration needs to be applied to enable AspectJ byte code weaving.

JVM configuration should include: -javaagent:[GRIDGAIN_HOME]/libs/aspectjweaver-1.5.3.jar
Classpath should contain the [GRIDGAIN_HOME]/config/aop/aspectj folder.

Running Grid Node

This example will need one remote node to be running. Note that you don't need another machine for it - you can start remote node on the same machine you are running example on.

To start a remote node open the terminal window on Linux/Mac OS X or Command Prompt on Windows, change directory to ${GRIDGAIN_HOME}/bin and run the gridgain.{sh|bat} script. It takes 2-3 seconds for grid node to start and if everything worked fine you should see starting log ending with successful start acknowledgment.

GridifyHelloWorldTaskExample.java

1. Import GridGain classes.

import org.gridgain.grid.*;
import org.gridgain.grid.gridify.*;

2. Add Grid Start and Stop.

GridFactory.start();
        
try {
    ...
}
finally {
    GridFactory.stop(true);
}

finally clause allows for graceful grid shutdown in case of the exceptions.

3. Add `@Gridify` Annotation.

We add @Gridify ^Javadoc annotation specifying custom task class we use responsible for splitting method execution into sub-jobs.

@Gridify(taskClass = GridifyHelloWorldTask.class, timeout = 3000)
public static int sayIt(String phrase) {
    // Simply print out the argument.
    System.out.println(">>>");
    System.out.println(">>> Printing '" + phrase + "' on this node from grid-enabled method.");
    System.out.println(">>>");

    return phrase.length();
}

Full Source Code

GridifyHelloWorldTaskExample.java

package org.gridgain.examples.helloworld.gridify.task;

import org.gridgain.grid.*;
import org.gridgain.grid.gridify.*;

public final class GridifyHelloWorldTaskExample {
    /**
     * Ensure singleton.
     */
    private GridifyHelloWorldTaskExample() {
        // No-op.
    }

    /**
     * Method grid-enabled with {@link Gridify} annotation. Simply prints
     * out the argument passed in. Note that in this case instead of
     * using default task, we provide our own task which will split
     * the passed in string into separate words to be printed on
     * remote nodes.
     *
     * @param arg String to print.
     */
    @Gridify(taskClass = GridifyHelloWorldTask.class, timeout = 3000)
    public static int sayIt(String phrase) {
        // Simply print out the argument.
        System.out.println(">>>");
        System.out.println(">>> Printing '" + phrase + "' on this node from grid-enabled method.");
        System.out.println(">>>");

        return phrase.length();
    }

    /**
     * Execute <tt>HelloWorld</tt> example grid-enabled with
     * <tt>Gridify</tt> annotation.
     *
     * @param args Command line arguments, none required but if provided
     *      first one should point to the Spring configuration file. See
     *      <tt>"examples/config/"</tt> for configuration file examples.
     * @throws GridException If example execution failed.
     */
    public static void main(String[] args) throws GridException {
        if (args.length == 0) {
            GridFactory.start();
        }
        else {
            GridFactory.start(args[0]);
        }

        try {
            // This method will be executed on a remote grid nodes.
            int phraseLen = sayIt("Hello World");

            System.out.println(">>>");
            System.out.println(">>> Finished executing Gridify \"Hello World\" example with custom task.");
            System.out.println(">>> Total number of characters in the phrase is '" + phraseLen + "'.");
            System.out.println(">>> You should see print out of 'Hello' on one node and 'World' on another node.");
            System.out.println(">>> Check all nodes for output (this node is also part of the grid).");
            System.out.println(">>>");
        }
        finally {
            GridFactory.stop(true);
        }
    }
}

GridifyHelloWorldTask.java

1. Import GridGain classes.

import org.gridgain.grid.*;
import org.gridgain.grid.gridify.*;

2. Split Logic.

This is a grid task implementation that is responsible for split and aggregate (a.k.a map/reduce) logic. Note that this implementation uses GridifyTaskSplitAdapter ^Javadoc that simplifies API for grid tasks in homogeneous grids (which is often the case). Main two methods that are implemented here are split and reduce. Method reduce aggregates results (sums up numbers returned from jobs) to get string length.

This grid task is responsible for splitting the passed in string into separate words and then passing each word into its own grid job for execution on remote nodes.

Full Source Code

GridifyHelloWorldTask.java

package org.gridgain.examples.helloworld.gridify.task;

import java.io.*;
import java.util.*;
import org.gridgain.grid.*;
import org.gridgain.grid.gridify.*;

/**
 * This grid task is responsible for splitting the passed in string into
 * separate words and then passing each word into its own grid job
 * for execution on remote nodes. 
 */
public class GridifyHelloWorldTask extends GridifyTaskSplitAdapter<Integer> {
    /**
     * {@inheritDoc}
     */
    @Override
    protected Collection<? extends GridJob> split(int gridSize, GridifyArgument arg) throws GridException {
        String[] words = ((String)arg.getMethodParameters()[0]).split(" ");

        List<GridJobAdapter<String>> jobs = new ArrayList<GridJobAdapter<String>>(words.length);

        for (String word : words) {
            // Every job gets its own word as an argument.
            jobs.add(new GridJobAdapter<String>(word) {
                /**
                 * Simply executes {@link GridifyHelloWorldTaskExample#sayIt(String)} method
                 * with passed in argument.
                 */
                public Serializable execute() throws GridException {
                    // Execute gridified method.
                    // Note that since we are calling this method from within the grid job
                    // AOP-based grid enabling will not cross-cut it and method will just
                    // execute normally.
                    return GridifyHelloWorldTaskExample.sayIt(getArgument());
                }
            });
        }

        return jobs;
    }

    /**
     * Sums up all characters from all jobs and returns a
     * total number of characters in the initial phrase.
     *
     * @param results Job results.
     * @return Number of characters for the 'phrase' passed into
     *      {@link GridifyHelloWorldTaskExample#sayIt(String)} method.
     * @throws GridException If reduce failed.
     */
    public Integer reduce(List<GridJobResult> results) throws GridException {
        int totalCharCnt = 0;

        for (GridJobResult res : results) {
            // Every job returned a number of letters
            // for the phrase it was responsible for.
            Integer charCnt = res.getData();

            totalCharCnt += charCnt;
        }
        
        // Account for spaces. For simplicity we assume one space between words.
        totalCharCnt += results.size() - 1;

        // Total number of characters in the phrase
        // passed into task execution.
        return totalCharCnt;
    }
}

Page Operations

Browse Space

Gridify With Custom Task Example

AspectJ AOP Configuration

Running Grid Node

GridifyHelloWorldTaskExample.java

1. Import GridGain classes.

2. Add Grid Start and Stop.

3. Add `@Gridify` Annotation.

Full Source Code

GridifyHelloWorldTask.java

1. Import GridGain classes.

2. Split Logic.

Full Source Code

Page Operations

Browse Space

Gridify With Custom Task Example

AspectJ AOP Configuration

Running Grid Node

GridifyHelloWorldTaskExample.java

1. Import GridGain classes.

2. Add Grid Start and Stop.

3. Add @Gridify Annotation.

Full Source Code

GridifyHelloWorldTask.java

1. Import GridGain classes.

2. Split Logic.

Full Source Code

3. Add `@Gridify` Annotation.