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From b..@petinou.fr
Subject Re: How to manage several service instances with declarative services?
Date Tue, 12 Jan 2016 10:21:15 GMT
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, ben@petinou.fr 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, ben@petinou.fr 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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