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 Servi         


        

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("\n");        
}


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 + "\n2 " + message + "\n3 " + message + "\n";

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

        Dictionary properties = new Hashtable();
        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 fetchService(BundleContext context, Class 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:

    4.0.0
    net.earcam
    net.earcam.example.servicecomponent
    0.0.1-SNAPSHOT
    jar

    
        1.6
        1.6

        4.2.0
        2.1.0
        1.7.4
        2.3.1
        UTF-8
    

    
        
            org.osgi
            org.osgi.core
            ${version.osgi}
            provided
        

        
            org.osgi
            org.osgi.compendium
            ${version.osgi}
            provided
        

        
            org.apache.felix
            org.apache.felix.scr.annotations
            1.4.0
            provided
        

        
            junit
            junit
            4.8.2
            test
        

        
            org.hamcrest
            hamcrest-core
            1.3.RC2
            test
        

        
            org.jmock
            jmock-junit4
            2.5.1
            test
        

        
            org.slf4j
            slf4j-simple
            1.6.1
            test
        

        
            org.ops4j.pax.exam
            pax-exam-junit4
            ${version.paxexam}
            test
        

        
            org.ops4j.pax.exam
            pax-exam-container-paxrunner
            ${version.paxexam}
            test
        

        
            org.ops4j.pax.exam
            pax-exam-link-assembly
            ${version.paxexam}
            test
        

        
            org.ops4j.pax.exam
            pax-exam-testforge
            ${version.paxexam}
            test
        

        
            org.ops4j.pax.runner
            pax-runner-no-jcl
            ${version.paxrunner}
            test
        

        
            org.apache.felix
            org.apache.felix.scr
            1.6.0
            test
        
    

    
        
            
                org.apache.maven.plugins
                maven-compiler-plugin
                2.3.2
                
                    ${version.java.source}
                    ${version.java.target}
                    ${project.build.sourceEncoding}
                
            

            
                
                org.apache.maven.plugins
                maven-surefire-plugin
                2.8.1
                
                    
                        
                            test
                        
                    
                
                
                    
                        **/*IntegrationTest.java
                    
                
            

            
                
                org.codehaus.mojo
                failsafe-maven-plugin
                2.4.3-alpha-1
                
                    
                        
                            integration-test
                            verify
                        
                        integration-test
                    
                
                
                    
                        **/*IntegrationTest.java
                    
                
            

            
                org.ops4j.pax.exam
                maven-paxexam-plugin
                1.2.3
                
                    
                        generate-config
                        
                            generate-depends-file
                        
                    
                
            

            
                
                org.apache.felix
                maven-scr-plugin
                1.6.0
                
                    
                        generate-scr-descriptor
                        
                            scr
                        
                        process-classes
                        
                            true
                            ${project.build.outputDirectory}/
                        
                    
                
            


            
                
                org.apache.felix
                maven-bundle-plugin
                2.3.4
                true
                
                    
                        jar
                    
                    
                        earcam
                        OSGI-INF/serviceComponents.xml
                        
                        ${project.artifactId}
                        ${project.version}
                        !${project.artifactId}.internal,${project.artifactId}.*
                        *
                    
                
                
                    
                        bundle-manifest
                        process-classes
                        
                            manifest
                        
                    
                
            

            
                org.apache.maven.plugins
                maven-jar-plugin
                2.3.1
                
                    
                        ${project.build.outputDirectory}/META-INF/MANIFEST.MF
                    
                
            

        
    

A couple of things to note; I like my integration tests inside the module they test, that way mvn clean install deploy fails if my integration test does - but it's common to see projects with a single integration module for all integration tests. This explains the ugly method findFileInCurrentDirectoryAndBelow(Pattern pattern) which is used to locate the current module's bundle in the target directory, and also explains the non-standard setup of the maven-bundle-plugin and maven-scr-plugin plugins.

Also the way Pax-Exam picks up the dependencies requires you run the maven build for every change in dependencies and config (e.g. bundle imports/exports, DS changes). But once this is done you can run/debug the tests from Eclipse.

I've put the project in a tarball here

HTH =)