java - osgi: Using ServiceFactories?

Question

I'm currently trying to get a simple bundle containing a Service Factory running.

This is my factory class:

public class SvcFactory implements ServiceFactory<ServiceB> {

    @Override
    public ServiceB getService(Bundle bundle,
            ServiceRegistration<ServiceB> registration) {

        return new ServiceBImpl();
    }

    @Override
    public void ungetService(Bundle bundle, ServiceRegistration<ServiceB> registration,
            ServiceB service) {

    }

}

This is my service that should be created by the factory:

public class ServiceBImpl implements ServiceB {

    private ServiceA svcA;

    public void setA(ServiceA a) {
        svcA = a;
    }

}

And finally the OSGI-INF/component.xml

<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.1.0" name="bundleb.internal.SvcFactory">

   <implementation class="bundleb.internal.SvcFactory"/>

  <reference bind="setA" cardinality="1..1" interface="bundlea.ServiceA" name="ServiceA" policy="static"/>

   <service servicefactory="true">
      <provide interface="bundleb.ServiceB"/>
   </service>
</scr:component>

If I run my test bundles (A, B and C) within equinox I'm getting the following error:

org.osgi.framework.ServiceException: org.eclipse.equinox.internal.ds.FactoryReg.getService() returned a service object that is not an instance of the service class bundleb.ServiceB

I can't find much information about using ServiceFeactories declared in a component definition on the internet. Even the book "OSGi and Equinox" didn't tell me much about using them. Could anyone please explain to me what I'm doing wrong?

Answer 1

Here's an example using ComponentFactory which should fit your needs (and contains a simple integration test to aid with your other question). Disclaimer; the code isn't well written, just for example's sake.

Some service interfaces:

package net.earcam.example.servicecomponent;

public interface EchoService {

    String REPEAT_PARAMETER = "repeat";
    String FACTORY_DS = "echo.factory";
    String NAME_DS = "echo";

    String echo(String message);
}

And:

package net.earcam.example.servicecomponent;

public interface SequenceService {
    long next();
}

Then the implementations:

import static net.earcam.example.servicecomponent.EchoService.FACTORY_DS;
import static net.earcam.example.servicecomponent.EchoService.NAME_DS;
import static org.apache.felix.scr.annotations.ReferenceCardinality.MANDATORY_UNARY;
import static org.apache.felix.scr.annotations.ReferencePolicy.DYNAMIC;
import net.earcam.example.servicecomponent.EchoService;
import net.earcam.example.servicecomponent.SequenceService;

import org.apache.felix.scr.annotations.Activate;
import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Reference;
import org.osgi.service.component.ComponentContext;

@Component(factory = FACTORY_DS, name = NAME_DS)
public class EchoServiceImp implements EchoService {

    @Reference(cardinality = MANDATORY_UNARY, policy = DYNAMIC)
    private SequenceService sequencer = null;
    private transient int repeat = 1;

    @Activate
protected void activate(final ComponentContext componentContext)
{
    repeat = Integer.parseInt(componentContext.getProperties().get(REPEAT_PARAMETER).toString());
}


@Override
public String echo(final String message)
{
    StringBuilder stringBuilder = new StringBuilder();
    for(int i = 0; i < repeat; i++) {
        addEchoElement(stringBuilder, message);
    }
    return stringBuilder.toString();
}


private void addEchoElement(final StringBuilder stringBuilder, final String message) {
    stringBuilder.append(sequencer.next()).append(' ').append(message).append("
");        
}


protected void unbindSequencer()
{
    sequencer = null;
}


protected void bindSequencer(final SequenceService sequencer)
{
    this.sequencer = sequencer;
}

}

And:

package net.earcam.example.servicecomponent.internal;

import java.util.concurrent.atomic.AtomicLong;

import net.earcam.example.servicecomponent.SequenceService;

import org.apache.felix.scr.annotations.Activate;
import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Deactivate;
import org.apache.felix.scr.annotations.Service;

/**
 * @author caspar
 */
@Component
@Service
public class SequenceServiceImp implements SequenceService {

    private AtomicLong sequence;


    @Override
    public long next()
    {
        return sequence.incrementAndGet();
    }


    @Activate
    protected void activate()
    {
        sequence = new AtomicLong();
    }


    @Deactivate
    protected void deactivate()
    {
        sequence = null;
    }
}

An integration test that drives the whole thing (note; there's a main method so you run it while start/stopping bundles etc).

package net.earcam.example.servicecomponent.test;

import static org.ops4j.pax.exam.CoreOptions.*;
import static org.ops4j.pax.exam.OptionUtils.combine;
import static org.ops4j.pax.exam.spi.container.PaxExamRuntime.createContainer;
import static org.ops4j.pax.exam.spi.container.PaxExamRuntime.createTestSystem;

import java.io.File;
import java.io.FileFilter;
import java.io.FileNotFoundException;
import java.util.Dictionary;
import java.util.Hashtable;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import net.earcam.example.servicecomponent.EchoService;
import net.earcam.example.servicecomponent.SequenceService;

import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.ops4j.pax.exam.Option;
import org.ops4j.pax.exam.junit.Configuration;
import org.ops4j.pax.exam.junit.ExamReactorStrategy;
import org.ops4j.pax.exam.junit.JUnit4TestRunner;
import org.ops4j.pax.exam.spi.reactors.EagerSingleStagedReactorFactory;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.osgi.service.component.ComponentFactory;
import org.osgi.service.component.ComponentInstance;


@ExamReactorStrategy(EagerSingleStagedReactorFactory.class)
@RunWith(JUnit4TestRunner.class)
public class EchoServiceIntegrationTest {


    public static void main(String[] args) {
        try {
            createContainer(
                    createTestSystem(
                            combine(
                                    new EchoServiceIntegrationTest().config(), 
                                    profile("gogo"))
                    )).start();
        } catch(Throwable t) {
            t.printStackTrace();
        }
    }



    @Configuration
    public Option[] config()
    {
        return options(
                felix(),
                equinox(),
                junitBundles(),
                systemProperty("org.ops4j.pax.logging.DefaultServiceLog.level").value("TRACE"),
                mavenBundle().groupId("org.apache.felix").artifactId("org.apache.felix.scr").versionAsInProject(),
                bundle("file:" + findFileInCurrentDirectoryAndBelow(
                        Pattern.compile("net\.earcam\.example\.servicecomponent\-[\.\d]+(\-SNAPSHOT)?\.[wj]ar")))
        );
    }


    @Test
    public void bundleContextIsAvailable(BundleContext context)
    {
        Assert.assertNotNull("PAX Exam BundleContext available", context);
    }


    @Test
    public void sequenceServiceIsAvailable(BundleContext context)
    {
        Assert.assertNotNull("SequenceService available", fetchService(context, SequenceService.class));
    }


    @Test
    public void serviceResponseContainsThreeEchos(BundleContext context) throws Exception
    {
        final String message = "message";
        final String expected = "1 " + message + "
2 " + message + "
3 " + message + "
";

        ComponentFactory factory = fetchComponentFactory(context, EchoService.FACTORY_DS);

        Dictionary<String, String> properties = new Hashtable<String, String>();
        properties.put(EchoService.REPEAT_PARAMETER, "3");
        ComponentInstance instance = factory.newInstance(properties);
        EchoService service = (EchoService) instance.getInstance();
        String actual = service.echo(message);
        Assert.assertEquals("Expected response", expected, actual);
    }


    private ComponentFactory fetchComponentFactory(BundleContext context, String componentFactoryId) throws Exception
    {
        String filter = "(component.factory=" + componentFactoryId + ")";
        ServiceReference[] references = context.getServiceReferences(ComponentFactory.class.getCanonicalName(), filter);
        return (references.length) == 0 ?  null : (ComponentFactory) context.getService(references[0]);
    }


    private <T> T fetchService(BundleContext context, Class<T> clazz)
    {
        ServiceReference reference = context.getServiceReference(clazz.getCanonicalName());
        @SuppressWarnings("unchecked")
        T service = (T) context.getService(reference);
        return service;
    }


    private String findFileInCurrentDirectoryAndBelow(final Pattern filePattern) {
        FileFilter filter = new FileFilter() {
            @Override
            public boolean accept(File pathname) {
                Matcher matcher = filePattern.matcher(pathname.getName());
                return (matcher.matches());
            }
        };
        return findFile(new File("."), filter, filePattern);
    }


    private String findFile(File directory, FileFilter filter, Pattern filePattern) {
        File[] matches = directory.listFiles(filter);
        if(matches != null && matches.length > 0) {
            return matches[0].getAbsolutePath();
        }
        File[] subdirs = directory.listFiles(new FileFilter() {
            @Override
            public boolean accept(File pathname) {
                return pathname.isDirectory();
            }
        });
        for(final File subdir : subdirs) {
            String found = findFile(subdir, filter, filePattern);
            if(!"".equals(found)) {
                return found;
            }
        }
        throw new RuntimeException(new FileNotFoundException("No match for pattern: " + filePattern.pattern()));
    }
}

And here's the maven pom:

<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>net.earcam</groupId>
    <artifactId>net.earcam.example.servicecomponent</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <properties>
        <version.java.source>1.6</version.java.source>
        <version.java.target>1.6</version.java.target>

        <version.osgi>4.2.0</version.osgi>
        <version.paxexam>2.1.0</version.paxexam>
        <version.paxrunner>1.7.4</version.paxrunner>
        <version.cometd>2.3.1</version.cometd>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.osgi</groupId>
            <artifactId>org.osgi.core</artifactId>
            <version>${version.osgi}</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.osgi</groupId>
            <artifactId>org.osgi.compendium</artifactId>
            <version>${version.osgi}</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.apache.felix</groupId>
            <artifactId>org.apache.felix.scr.annotations</artifactId>
            <version>1.4.0</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.8.2</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.hamcrest</groupId>
            <artifactId>hamcrest-core</artifactId>
            <version>1.3.RC2</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.jmock</groupId>
            <artifactId>jmock-junit4</artifactId>
            <version>2.5.1</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-simple</artifactId>
            <version>1.6.1