[jira] Commented: (FELIX-2563) service factory causes cast error

["Felix Meschberger (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FELIX-2563?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12904145#action_12904145 ] 

Felix Meschberger commented on FELIX-2563:
------------------------------------------

I think this is related to a misunderstanding.

If you declare a service to be a service factory, this is an indication to the Declarative Services how to cope with the component. As for the class of your component: You just implement the actual service class and don't care for registering and implementing the ServiceFactory interface.

For example:

   <?xml version="1.0" encoding="UTF-8"?>
   <scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.1.0" name="dsbug.LongFactory">
     <implementation class="Test"/>
     <service servicefactory="true">
       <provide interface="Test />
     </service>
   </scr:component>

Your implementation would be :

   public class Test  {
      ... do something ....
   }

DS will create a ServiceFactory object, register it under the name "Test" and implement required creation and drop implementations to create your Test instances. Your component does not have to care for this and does not have to maintain these instances.

> service factory causes cast error
> ---------------------------------
>
>                 Key: FELIX-2563
>                 URL: https://issues.apache.org/jira/browse/FELIX-2563
>             Project: Felix
>          Issue Type: Bug
>          Components: Declarative Services (SCR)
>    Affects Versions:  scr-1.6.0
>            Reporter: Christopher Brind
>            Priority: Minor
>         Attachments: dsbug.jar
>
>
> Given this component XML:
> <?xml version="1.0" encoding="UTF-8"?> 
> <scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.1.0" name="dsbug.LongFactory">
> 	<implementation class="dsbug.LongFactory"/> 
> 	
> 	<service servicefactory="true">
> 		<provide interface="java.lang.Long" />
> 	</service>
> </scr:component>
> And given this component class:
> package dsbug;
> import org.osgi.framework.Bundle;
> import org.osgi.framework.ServiceFactory;
> import org.osgi.framework.ServiceRegistration;
> public class LongFactory implements ServiceFactory {
> 	public Object getService(Bundle bundle, ServiceRegistration registration) {
> 		return new Long(bundle.getBundleId());
> 	}
> 	public void ungetService(Bundle bundle, ServiceRegistration registration,
> 			Object service) {
> 	}
> 	
> }
> Causes this error when referencing the service factory (resulting in unsatisfied dependencies):
> org.apache.felix.log.LogException: org.osgi.framework.ServiceException: Service cannot be cast: java.lang.Long
> However, when using this Activator *instead* of DS, all is well:
> package dsbug;
> import org.osgi.framework.BundleActivator;
> import org.osgi.framework.BundleContext;
> public class Activator implements BundleActivator {
> 	public void start(BundleContext context) throws Exception {
> 		context.registerService(Long.class.getName(), new LongFactory(), null);
> 	}
> 	public void stop(BundleContext context) throws Exception {
> 	}
> }
> Workaround (with DS) is to create a simple component with an activate(BundleContext ctx) method and manually register the service. 

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