Wednesday, September 4, 2013

Exploring Apache Camel Core - DataSet Component

A good sample data generator can help you test program more throughly and help measure the processing throughput. The camel-core comes with a dataset component that can help you do this easily. All you need is to provide a bean that implements org.apache.camel.component.dataset.DataSet interface and bind it in CamelContext registry. Here is an example:

package camelcoredemo;

import org.slf4j.*;
import org.apache.camel.*;
import org.apache.camel.builder.*;
import org.apache.camel.main.Main;
import org.apache.camel.component.dataset.*;

public class DataSetDemoCamel extends Main {
    static Logger LOG = LoggerFactory.getLogger(DataSetDemoCamel.class);
    public static void main(String[] args) throws Exception {
        DataSetDemoCamel main = new DataSetDemoCamel();
        main.enableHangupSupport();
        main.addRouteBuilder(createRouteBuilder());
        main.bind("sampleGenerator", createDataSet());
        main.run(args);
    }
    static RouteBuilder createRouteBuilder() {
        return new RouteBuilder() {
            public void configure() {
                from("dataset://sampleGenerator")
                .to("log://demo");
            }
        };
    }
    static DataSet createDataSet() {
        return new SimpleDataSet();
    }
}

Compile and run it.

mvn compile exec:java -Dexec.mainClass=camelcoredemo.DataSetDemoCamel

In here we have used the built-in org.apache.camel.component.dataset.SimpleDataSet implementation, which by default will generate 10 messages with a text body set to <hello>world!</hello>. You may easily change the value, or even provide your own implementation starting with org.apache.camel.component.dataset.DataSetSupport base class to customize your data set.

Use DataSet Component to measure throughput

One useful feature of dataset component I found is using it to load test your Route. To do this, you have to adjust couple settings though. Let’s say if I want to load a large text file as sample input data and feed it to the Route, and then measure its throughout.

    static RouteBuilder createRouteBuilder() {
        return new RouteBuilder() {
            public void configure() {
                from("dataset://sampleGenerator?produceDelay=0")
                .to("log://demo?groupSize=100");
            }
        };
    }
    static DataSet createDataSet() {
        SimpleDataSet result = new SimpleDataSet();
        result.setSize(500);
        result.setDefaultBody(readFileToString("my-large-sample.txt");
        return result;
    }

Replace above in the Main class and you will notice that it will pump 500 messages into the Route, and it samples every 100 messages and display its throught rates. I have to add produceDelay=0 option so the generator so it will not pause between messages. Then I have added groupSize=100 option to log component for throughput measurement. I skipped readFileToString(String) demo code since I assume you can easily figured that out on your own. (Hint: checkout Apache commons-io library.)

There is another side of dataset component that you may use, and that is to receive and verify message content. You would simply use the same URL in a to(url) line. Internally Camel would assert your message body against your original.

There are more options availabe from DataSet component that you may explore. Try it out with a Route and see it for yourself.