Hi everyone,
I have a ComponentException in Felix SCR that I don't understand.
Here is my use case:
1) I have a file reader service that reads a file:
public interface FileReaderService {
/**
* Reads the given file.
* @param filePath Path of the file to read
* @return the data object built from the file
* @throws IOException if there is an error while reading the file
*/
String readFile(Path filePath) throws IOException;
/**
* Detects if the format of the provided file is supported.
* @param filePath the file to check
* @return true if the format of the file is supported, false
otherwise
* @throws IOException if there is an error while reading the file
*/
boolean isFormatSupported(Path filePath) throws IOException;
}
2) I then have several implementations such as:
@Component
public class TxtFileReader implements FileReaderService {
@Override
public String readFile(Path filePath) throws IOException {
// Do something smart with the file
return "";
}
@Override
public boolean isFormatSupported(Path filePath) throws IOException {
PathMatcher matcher =
FileSystems.getDefault().getPathMatcher("glob:*.txt");
return matcher.matches(filePath);
}
}
3) I want a "factory" that would use the appropriate service depending
on the file format:
@Component
public class FileReaderFactory implements ReaderFactoryService {
@Reference
private List<FileReaderService> availableServices;
@Override
public String readFile(Path filePath) throws IOException {
for (FileReaderService reader : availableServices) {
if (reader.isFormatSupported(filePath)) {
return reader.readFile(filePath);
}
}
return null;
}
@Override
public boolean isFormatSupported(Path filePath) throws IOException {
for (FileReaderService reader : availableServices) {
if (reader.isFormatSupported(filePath)) {
return true;
}
}
return false;
}
}
The source code can be found 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 features. When you start
karaf and type scr:list, you see the two readers with null status. The
factory is not there at all.
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 (can be found in
Assembly/target/assembly/data/log/karaf.log):
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]
Any idea how to solve this?
Kind regards,
Ben
P.S. : I already posted my question on Stackoverflow
http://stackoverflow.com/questions/34706041/how-to-manage-several-service-instances-with-declarative-services
and on Karaf mailing list
http://mail-archives.apache.org/mod_mbox/karaf-dev/201601.mbox/%3C86ce97d48759d7f266072e86986f0cf3%40petinou.fr%3E
I know cross-posting is bad (sorry about that), but I think I didn't
choose wisely where to post before. My problem seems to be more Felix
SCR-related, so here I am. I will of course update all posts when I find
an answer to my problem.
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