Hi David,

I just pushed my sample project on GitHub: https://github.com/neopium/FileReader

You can get it from here and build it. I configured it so that it generates a Karaf assembly with the required feature. When you start karaf and type scr:list, you see the two readers with null status. The factory is not there.

Here is the generated component xml file:

<?xml version="1.0" encoding="UTF-8"?>
<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.3.0"; name="org.test.reader.service.factory.FileReaderFactory"> <implementation class="org.test.reader.service.factory.FileReaderFactory"/>
  <service>
    <provide interface="org.test.reader.service.ReaderFactoryService"/>
  </service>
<reference name="availableServices" interface="org.test.reader.service.FileReaderService" field="availableServices" field-collection-type="service"/>
</scr:component>

Here is the full stacktrace:

2016-01-12 11:12:36,961 | ERROR | pool-8-thread-1 | file-reader-service-impl | 9 - file-reader-service-impl - 1.0.0.SNAPSHOT | [org.test.reader.service.factory.FileReaderFactory] Cannot register Component org.osgi.service.component.ComponentException: Component org.test.reader.service.factory.FileReaderFactory validation failed: Field value type must not be set for unary field references. at org.apache.felix.scr.impl.metadata.ComponentMetadata.validationFailure(ComponentMetadata.java:953)[24:org.apache.felix.scr:2.0.2] at org.apache.felix.scr.impl.metadata.ReferenceMetadata.validate(ReferenceMetadata.java:710)[24:org.apache.felix.scr:2.0.2] at org.apache.felix.scr.impl.metadata.ComponentMetadata.validate(ComponentMetadata.java:873)[24:org.apache.felix.scr:2.0.2] at org.apache.felix.scr.impl.BundleComponentActivator.loadDescriptor(BundleComponentActivator.java:454)[24:org.apache.felix.scr:2.0.2] at org.apache.felix.scr.impl.BundleComponentActivator.initialize(BundleComponentActivator.java:309)[24:org.apache.felix.scr:2.0.2] at org.apache.felix.scr.impl.BundleComponentActivator.<init>(BundleComponentActivator.java:270)[24:org.apache.felix.scr:2.0.2] at org.apache.felix.scr.impl.Activator.loadComponents(Activator.java:358)[24:org.apache.felix.scr:2.0.2] at org.apache.felix.scr.impl.Activator.access$000(Activator.java:53)[24:org.apache.felix.scr:2.0.2] at org.apache.felix.scr.impl.Activator$ScrExtension.start(Activator.java:260)[24:org.apache.felix.scr:2.0.2] at org.apache.felix.utils.extender.AbstractExtender.createExtension(AbstractExtender.java:259)[24:org.apache.felix.scr:2.0.2] at org.apache.felix.utils.extender.AbstractExtender.modifiedBundle(AbstractExtender.java:232)[24:org.apache.felix.scr:2.0.2] at org.osgi.util.tracker.BundleTracker$Tracked.customizerModified(BundleTracker.java:482)[org.osgi.core-6.0.0.jar:] at org.osgi.util.tracker.BundleTracker$Tracked.customizerModified(BundleTracker.java:415)[org.osgi.core-6.0.0.jar:] at org.osgi.util.tracker.AbstractTracked.track(AbstractTracked.java:232)[org.osgi.core-6.0.0.jar:] at org.osgi.util.tracker.BundleTracker$Tracked.bundleChanged(BundleTracker.java:444)[org.osgi.core-6.0.0.jar:] at org.apache.felix.framework.util.EventDispatcher.invokeBundleListenerCallback(EventDispatcher.java:916)[org.apache.felix.framework-5.4.0.jar:] at org.apache.felix.framework.util.EventDispatcher.fireEventImmediately(EventDispatcher.java:835)[org.apache.felix.framework-5.4.0.jar:] at org.apache.felix.framework.util.EventDispatcher.fireBundleEvent(EventDispatcher.java:517)[org.apache.felix.framework-5.4.0.jar:] at org.apache.felix.framework.Felix.fireBundleEvent(Felix.java:4541)[org.apache.felix.framework-5.4.0.jar:] at org.apache.felix.framework.Felix.startBundle(Felix.java:2172)[org.apache.felix.framework-5.4.0.jar:] at org.apache.felix.framework.BundleImpl.start(BundleImpl.java:998)[org.apache.felix.framework-5.4.0.jar:] at org.apache.felix.framework.BundleImpl.start(BundleImpl.java:984)[org.apache.felix.framework-5.4.0.jar:] at org.apache.karaf.features.internal.service.FeaturesServiceImpl.startBundle(FeaturesServiceImpl.java:1189)[7:org.apache.karaf.features.core:4.0.3] at org.apache.karaf.features.internal.service.Deployer.deploy(Deployer.java:836)[7:org.apache.karaf.features.core:4.0.3] at org.apache.karaf.features.internal.service.FeaturesServiceImpl.doProvision(FeaturesServiceImpl.java:1079)[7:org.apache.karaf.features.core:4.0.3] at org.apache.karaf.features.internal.service.FeaturesServiceImpl$1.call(FeaturesServiceImpl.java:975)[7:org.apache.karaf.features.core:4.0.3] at java.util.concurrent.FutureTask.run(FutureTask.java:266)[:1.8.0_65] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)[:1.8.0_65] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)[:1.8.0_65]
        at java.lang.Thread.run(Thread.java:745)[:1.8.0_65]


Le 11.01.2016 19:54, David Jencks a écrit :
Well, you got farther anyway :-)  I don’t yet see what’s wrong.  Could
you supply the generated component xml and the ComponentException
stack trace?

With bnd 3+ you don’t (shouldn’t?) need to specify
(service=FileReader.class) as now bnd can analyze the generic
method/field signature to infer the service type.

thanks
david jencks
On Jan 11, 2016, at 9:56 AM, [email protected] wrote:

Thanks David,

I tried that by get an error on karaf startup:
cannot register Component org.osgi.service.component.ComponentException: Component FileReaderFactory validation failed: Field value type must not be set for unary field references.

My class looks like this:

@Component
public class FileReaderFactory implements ReaderManager {
   @Reference(service = FileReader.class)
   private List<FileReader> availableServices;

   @Override
   public Data readFile(Path filePath) throws IOException {
       for (FileReader reader : availableServices) {
           if (reader.isFormatSupported(filePath)) {
               return reader.readFile(filePath);
           }
       }
       return null;
   }

   @Override
public boolean isFormatSupported(Path filePath) throws IOException {
       for (FileReader reader : availableServices) {
           if (reader.isFormatSupported(filePath)) {
               return true;
           }
       }
       return false;
   }
}

Le 11.01.2016 18:47, David Jencks a écrit :
Well, you need cmpn 6 for the ds 1.3 annotations (in particular
@Reference applicable to a field).  I thought this was on maven
central but haven’t looked. If necessary you can get it from the OSGI
site.
david jencks
On Jan 11, 2016, at 12:35 AM, [email protected] wrote:
Hi everyone!
I asked a question on stackoverflow regarding the use of Declarative Services in Karaf to manage multiple instances of a service, provided by different implementations of such a service.
The question is explained in details here:
http://stackoverflow.com/questions/34706041/how-to-manage-several-service-instances-in-declarative-services
I received and answer telling me that using the @reference annotation on the list storing the services would solve my problem. For this, I would need to use DS 1.3. I thus asked on Karaf users mailing list what was the version of Felix SCR provided with Karaf 4.0.3 (http://mail-archives.apache.org/mod_mbox/karaf-user/201601.mbox/%3C8dbfa59508d5769609e2c78c0210c7aa%40petinou.fr%3E) and was told it was Felix SCR 2.0.2, which supports DS 1.3. So far so good. I was also kindly advised to ask this kind of questions here. So here I am :-) Following the answer on stackoverflow, I tried to add the @reference annotation to my service list like this:
@Reference(service = FileReader.class)
private List<FileReader> availableServices = new ArrayList<>();
But it does not compile: FileReaderFactory.java:[37,5] annotation type not applicable to this kind of declaration
My project has a dependency on:
<dependency>
  <groupId>org.osgi</groupId>
  <artifactId>org.osgi.compendium</artifactId>
  <version>5.0.0</version>
  <scope>provided</scope>
</dependency>
which seems to be the latest version available.
I thus tried the "older way" by using explicit bind/unbind methods like this:
  @Reference(service = FileReader.class, unbind = "removeService")
  public void addService(final FileReader serviceToAdd) {
      System.out.println("FileReaderFactory.addService");
      availableServices.add(serviceToAdd);
      System.out.println(availableServices);
  }
  public void removeService(final FileReader serviceToRemove) {
      System.out.println("FileReaderFactory.removeService");
      availableServices.remove(serviceToRemove);
      System.out.println(availableServices);
  }
If I have two implementations available, say TxtFileReader and XmlFileReader, only the first one is added to the list. The status of the second service (using scr:detail command) is "null".
What am I missing?
Kind regards,
Ben

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