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From "Felix Meschberger (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FELIX-3090) SCR factory components ignore reference target filters
Date Mon, 29 Aug 2011 06:49:37 GMT

    [ https://issues.apache.org/jira/browse/FELIX-3090?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13092660#comment-13092660
] 

Felix Meschberger commented on FELIX-3090:
------------------------------------------

Thanks for proposing the patch. While this may perfectly work, I think it is not entirely
correct:

(1) The getProperties() method is used to set the service registration properties, which I
would think are not part of the ComponentFactory service registration. Thus adding them might
be wrong. On the other hand, they might not hurt.

(2) The bigger issue is, that this only gives you part of the rent: A call to the newInstance
method may provide even more target properties and thus may cause the selection to become
entirely different. Consider a case where a service is registered with name="xyz". The ComponentFactory
is predefined with target filter name="abc". This causes the ComponentFactory to be unsatisifed
and not registered. Yet the newInstance method might have been called with a target filter
name="xyz" thus actually satisifying the reference - but since the default prevents satisfaction,
the newInstance method will never be called ....

(3) Theoretically timing may be such that the required service may just be unregistered between
the user of the ComponentFactory getting the ComponentFactory service and calling the newInstance
method in which case this would be a failure, too. So regardless of whether we do analyze
target filters for the ComponentFactory registration or not, a ComponentException may be thrown
on newInstance.

Given the second (and to some degree the third) issue, I am reluctant to such a patch.

> SCR factory components ignore reference target filters
> ------------------------------------------------------
>
>                 Key: FELIX-3090
>                 URL: https://issues.apache.org/jira/browse/FELIX-3090
>             Project: Felix
>          Issue Type: Bug
>          Components: Declarative Services (SCR)
>    Affects Versions:  scr-1.6.0
>            Reporter: Pierre De Rop
>
> This issue is described in the following post:
> http://www.mail-archive.com/users@felix.apache.org/msg10925.html
> Basically, when a component is declaring a factory (in order to register a ComponentFactory
in the registry), 
> then any extra Reference' target filters are not taken into acount.
> This is a problem because the ComponentFactory is registered in the registry even if
some References are not satisfied.
> Consider the following example (It uses the BND SCR annotations):
> @Component(factory = "AFactory")
> public class A {
>     @Reference(name="YDependency", target = "(name=Z)")
>     void bind(Y y) {
>         System.out.println("A.bind(" + y + ")");
>     }
>     @Activate
>     void start() {
>         System.out.println("A.start");
>     }
> }
> public interface Y {
> }
> @Component(properties = { "name=ZZZZZ" })
> public class YImpl implements Y {
> }
> @Component
> public class AFactory {
>     @Reference(target = "(component.factory=AFactory)")
>     void bind(ComponentFactory AFactory) {
>         System.out.println("AFactory.bind(" + AFactory + ")");
>         try {
>             ComponentInstance ci = AFactory.newInstance(null);
>             A a = (A) ci.getInstance();
>             System.out.println("Created " + a);
>         }
>         catch (Throwable t) {
>             t.printStackTrace();
>         }
>     }
> }
> Here, the "YDependency" Reference of the "A" component is not satisfied, but the ComponentFactory
for the
> "A" component is somehow registered, and when the "AFactory" component catches it, then
it get the following exception,
> when trying to instantiate the "A" component instance:
> org.osgi.service.component.ComponentException: Failed activating component
>         at org.apache.felix.scr.impl.manager.ComponentFactoryImpl.newInstance(ComponentFactoryImpl.java:120)
>         at test.scr.factory.AFactory.bind(AFactory.java:15)
>         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>         at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
>         at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
>         at java.lang.reflect.Method.invoke(Method.java:597)
>         at org.apache.felix.scr.impl.helper.BaseMethod.invokeMethod(BaseMethod.java:227)
>         at org.apache.felix.scr.impl.helper.BaseMethod.access$1(BaseMethod.java:219)
>         at org.apache.felix.scr.impl.helper.BaseMethod$Resolved.invoke(BaseMethod.java:591)
>         at org.apache.felix.scr.impl.helper.BaseMethod$NotResolved.invoke(BaseMethod.java:548)
>         at org.apache.felix.scr.impl.helper.BaseMethod.invoke(BaseMethod.java:472)
>         at org.apache.felix.scr.impl.manager.DependencyManager.invokeBindMethod(DependencyManager.java:1028)
>         at org.apache.felix.scr.impl.manager.DependencyManager.bind(DependencyManager.java:944)
>         at org.apache.felix.scr.impl.manager.DependencyManager.open(DependencyManager.java:868)
>         at org.apache.felix.scr.impl.manager.ImmediateComponentManager.createImplementationObject(ImmediateComponentManager.java:200)
>         at org.apache.felix.scr.impl.manager.ImmediateComponentManager.createComponent(ImmediateComponentManager.java:118)
>         at org.apache.felix.scr.impl.manager.AbstractComponentManager$Unsatisfied.activate(AbstractComponentManager.java:1013)
>         at org.apache.felix.scr.impl.manager.AbstractComponentManager.activateInternal(AbstractComponentManager.java:333)
>         at org.apache.felix.scr.impl.manager.AbstractComponentManager.enable(AbstractComponentManager.java:157)
>         at org.apache.felix.scr.impl.config.ImmediateComponentHolder.enableComponents(ImmediateComponentHolder.java:313)
>         at org.apache.felix.scr.impl.BundleComponentActivator.loadDescriptor(BundleComponentActivator.java:253)
>         at org.apache.felix.scr.impl.BundleComponentActivator.initialize(BundleComponentActivator.java:147)
>         at org.apache.felix.scr.impl.BundleComponentActivator.<init>(BundleComponentActivator.java:111)
>         at org.apache.felix.scr.impl.Activator.loadComponents(Activator.java:274)
>         at org.apache.felix.scr.impl.Activator.bundleChanged(Activator.java:192)
>         at org.apache.felix.framework.util.EventDispatcher.invokeBundleListenerCallback(EventDispatcher.java:807)
>         at org.apache.felix.framework.util.EventDispatcher.fireEventImmediately(EventDispatcher.java:729)
>         at org.apache.felix.framework.util.EventDispatcher.fireBundleEvent(EventDispatcher.java:610)
>         at org.apache.felix.framework.Felix.fireBundleEvent(Felix.java:3879)
>         at org.apache.felix.framework.Felix.startBundle(Felix.java:1850)
>         at org.apache.felix.framework.Felix.setActiveStartLevel(Felix.java:1192)
>         at org.apache.felix.framework.StartLevelImpl.run(StartLevelImpl.java:266)
>         at java.lang.Thread.run(Thread.java:662)

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