Re: [osgi-dev] Retrieving service configuration implementation in reference method

[Alain Picard via osgi-dev]

On Mon, Sep 3, 2018 at 9:27 AM Tim Ward  wrote:

>
>
> On 3 Sep 2018, at 12:46, Alain Picard  wrote:
>
> Tim,
>
> Regarding point 1, I feel like I dropped the ball and it makes sense.
>
>
> Not really, there genuinely is a bug in bnd 4.0, and it was only fixed in
> the 4.1 development stream recently (within the last week).
>
>
> Regarding point 2, I learned something about the use of converters to
> manage component property types (and not to use them anywhere). So I read
> in chapter 707 to find out how to do it and now I have an issue with my
> Class method, which throws an exception. The priority which is an integer
> works fine.
>
> Code:
> @Reference
> private void addRenderer(ConfiguredComponent scc, Map
> props) {
> this.scc = scc;
> Converter converter = Converters.standardConverter();
> RendererConfig config =
> converter.convert(props).to(RendererConfig.class);
>
> System.out.println("Adding renderer with Tester priority:" +
> config.tester_priority() + "full props" + props);
> System.out.println("Tester:" + config.tester_class());
> }
>
> And the exception is:
> java.lang.NoClassDefFoundError: comp.property.test.RendererFactory
> at
> org.osgi.util.converter.ConverterImpl.loadClassUnchecked(ConverterImpl.java:352)
> at
> org.osgi.util.converter.ConverterImpl$19.apply(ConverterImpl.java:157)
> at
> org.osgi.util.converter.ConverterImpl$19.apply(ConverterImpl.java:154)
> at org.osgi.util.converter.Rule$1.apply(Rule.java:67)
> at
> org.osgi.util.converter.CustomConverterImpl$ConvertingWrapper.to(CustomConverterImpl.java:162)
> at
> org.osgi.util.converter.ConvertingImpl$4.invoke(ConvertingImpl.java:809)
> at com.sun.proxy.$Proxy3.tester_class(Unknown Source)
> at
> comp.property.test.RendererFactory.addRenderer(RendererFactory.java:23)
>
> And the "swallowed exception is:
> java.lang.ClassNotFoundException: comp.property.test.RendererFactory not
> found by org.osgi.util.converter [6]
>
> org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation(BundleWiringImpl.java:1597)
>
> org.apache.felix.framework.BundleWiringImpl.access$300(BundleWiringImpl.java:79)
>
> org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.loadClass(BundleWiringImpl.java:1982)
> java.lang.ClassLoader.loadClass(Unknown Source)
>
> org.osgi.util.converter.ConverterImpl.loadClassUnchecked(ConverterImpl.java:350)
>
> any idea or is this is bug or a what.
>
>
> This is not a bug. Classes are “difficult” types as they cannot be easily
> loaded without knowing the module that should provide them. This is one of
> the many reasons that class names are discouraged throughout OSGi. In this
> case the service property that you’re trying to convert is a String class
> name, and the Converter is trying to load that class using its own class
> loader (it doesn’t have any other options). In Java EE they use the Thread
> Context ClassLoader as a hack to get around this, setting that to the
> “correct” ClassLoader to use when trying to load types from the application
> in server runtime code.
>
> You have several options to work around this.
>
>
>1. Your best option is not to use a class name as a service property
>at all, and avoid using the Class object. Reflectively loading classes is
>the beginning of much pain in OSGi, and using a different solution usually
>results in much better overall modularity.
>
> A bit of the chicken and egg problem. In converting from Eclipse extension
point I went from a "type safe" (at least tooling checked) class name in
plugin.xml to a string property that is unchecked and won't be auto-renamed
if changed. This solution attempts to address the issue of avoiding to use
a string.

>
>1. If you really do need access to the Class (why?) then return it
>from a method on the service so that it can be loaded by a bundle who knows
>how and where to load it from. This still leaves you with potential issues,
>but should be workable
>
> Why? Since I'm using a 3rd party library that pretty much expects it that
way and some legacy layers.

>
>1. Add a custom rule to your converter instance that uses the
>“correct” bundle class loader to load the class. This may be your own
>(potential for missing imports) the bundle that registered the service
>(potential for missing uses) or some other bundle (good luck finding it)!.
>
> I am thinking that here I can just simply do props.get("tester.class");
and get the full class name and call our code that already replicates the
behavior used for extension point to createExecutableExtension and that
calls bundle.loadClass. I then get the type safety at dev time, and I can
always manage the loading at runtime.

Thanks
Alain

>
> Best Regards,
>
> Tim
>
>
> Thanks
> Alain
>
>
> On Mon, Sep 3, 2018 at 6:12 AM Tim Ward  wrote:
>
>>
>> Problem 1:
>>
>> The Relevant bitts of the specification are:
>>
>> How component properties 

Re: [osgi-dev] Retrieving service configuration implementation in reference method

[Tim Ward via osgi-dev]

> On 3 Sep 2018, at 12:46, Alain Picard  wrote:
> 
> Tim,
> 
> Regarding point 1, I feel like I dropped the ball and it makes sense. 

Not really, there genuinely is a bug in bnd 4.0, and it was only fixed in the 
4.1 development stream recently (within the last week).

> 
> Regarding point 2, I learned something about the use of converters to manage 
> component property types (and not to use them anywhere). So I read in chapter 
> 707 to find out how to do it and now I have an issue with my Class method, 
> which throws an exception. The priority which is an integer works fine.
> 
> Code:
> @Reference
> private void addRenderer(ConfiguredComponent scc, Map 
> props) {
> this.scc = scc;
> Converter converter = Converters.standardConverter();
> RendererConfig config = 
> converter.convert(props).to(RendererConfig.class);
> 
> System.out.println("Adding renderer with Tester priority:" + 
> config.tester_priority() + "full props" + props);
> System.out.println("Tester:" + config.tester_class());
> }
> 
> And the exception is:
> java.lang.NoClassDefFoundError: comp.property.test.RendererFactory
> at 
> org.osgi.util.converter.ConverterImpl.loadClassUnchecked(ConverterImpl.java:352)
> at org.osgi.util.converter.ConverterImpl$19.apply(ConverterImpl.java:157)
> at org.osgi.util.converter.ConverterImpl$19.apply(ConverterImpl.java:154)
> at org.osgi.util.converter.Rule$1.apply(Rule.java:67)
> at 
> org.osgi.util.converter.CustomConverterImpl$ConvertingWrapper.to(CustomConverterImpl.java:162)
> at 
> org.osgi.util.converter.ConvertingImpl$4.invoke(ConvertingImpl.java:809)
> at com.sun.proxy.$Proxy3.tester_class(Unknown Source)
> at comp.property.test.RendererFactory.addRenderer(RendererFactory.java:23)
> 
> And the "swallowed exception is:
> java.lang.ClassNotFoundException: comp.property.test.RendererFactory not 
> found by org.osgi.util.converter [6]
> org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation(BundleWiringImpl.java:1597)
> org.apache.felix.framework.BundleWiringImpl.access$300(BundleWiringImpl.java:79)
> org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.loadClass(BundleWiringImpl.java:1982)
> java.lang.ClassLoader.loadClass(Unknown Source)
> org.osgi.util.converter.ConverterImpl.loadClassUnchecked(ConverterImpl.java:350)
> 
> any idea or is this is bug or a what.

This is not a bug. Classes are “difficult” types as they cannot be easily 
loaded without knowing the module that should provide them. This is one of the 
many reasons that class names are discouraged throughout OSGi. In this case the 
service property that you’re trying to convert is a String class name, and the 
Converter is trying to load that class using its own class loader (it doesn’t 
have any other options). In Java EE they use the Thread Context ClassLoader as 
a hack to get around this, setting that to the “correct” ClassLoader to use 
when trying to load types from the application in server runtime code.

You have several options to work around this.

Your best option is not to use a class name as a service property at all, and 
avoid using the Class object. Reflectively loading classes is the beginning of 
much pain in OSGi, and using a different solution usually results in much 
better overall modularity.
If you really do need access to the Class (why?) then return it from a method 
on the service so that it can be loaded by a bundle who knows how and where to 
load it from. This still leaves you with potential issues, but should be 
workable
Add a custom rule to your converter instance that uses the “correct” bundle 
class loader to load the class. This may be your own (potential for missing 
imports) the bundle that registered the service (potential for missing uses) or 
some other bundle (good luck finding it)!.

Best Regards,

Tim

> 
> Thanks
> Alain
> 
> 
> On Mon, Sep 3, 2018 at 6:12 AM Tim Ward  > wrote:
> 
> Problem 1:
> 
> The Relevant bitts of the specification are:
> 
> How component properties override each other at runtime:
> https://osgi.org/specification/osgi.cmpn/7.0.0/service.component.html#service.component-component.properties
>  
> 
> 
> How component properties override each other at build time:
> https://osgi.org/specification/osgi.cmpn/7.0.0/service.component.html#service.component-ordering.generated.properties
>  
> 
> 
> The sum total of this is that the component properties from the annotation 
> that you’ve applied to your component class should come *after* the ones from 
> the activate method. There was a very recent fix in Bnd 
>  to make sure that this was done 
> correctly.
> 
> 
> 

Re: [osgi-dev] Retrieving service configuration implementation in reference method

[Alain Picard via osgi-dev]

Tim,

Regarding point 1, I feel like I dropped the ball and it makes sense.

Regarding point 2, I learned something about the use of converters to
manage component property types (and not to use them anywhere). So I read
in chapter 707 to find out how to do it and now I have an issue with my
Class method, which throws an exception. The priority which is an integer
works fine.

Code:
@Reference
private void addRenderer(ConfiguredComponent scc, Map
props) {
this.scc = scc;
Converter converter = Converters.standardConverter();
RendererConfig config =
converter.convert(props).to(RendererConfig.class);

System.out.println("Adding renderer with Tester priority:" +
config.tester_priority() + "full props" + props);
System.out.println("Tester:" + config.tester_class());
}

And the exception is:
java.lang.NoClassDefFoundError: comp.property.test.RendererFactory
at
org.osgi.util.converter.ConverterImpl.loadClassUnchecked(ConverterImpl.java:352)
at
org.osgi.util.converter.ConverterImpl$19.apply(ConverterImpl.java:157)
at
org.osgi.util.converter.ConverterImpl$19.apply(ConverterImpl.java:154)
at org.osgi.util.converter.Rule$1.apply(Rule.java:67)
at
org.osgi.util.converter.CustomConverterImpl$ConvertingWrapper.to(CustomConverterImpl.java:162)
at
org.osgi.util.converter.ConvertingImpl$4.invoke(ConvertingImpl.java:809)
at com.sun.proxy.$Proxy3.tester_class(Unknown Source)
at
comp.property.test.RendererFactory.addRenderer(RendererFactory.java:23)

And the "swallowed exception is:
java.lang.ClassNotFoundException: comp.property.test.RendererFactory not
found by org.osgi.util.converter [6]
org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation(BundleWiringImpl.java:1597)
org.apache.felix.framework.BundleWiringImpl.access$300(BundleWiringImpl.java:79)
org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.loadClass(BundleWiringImpl.java:1982)
java.lang.ClassLoader.loadClass(Unknown Source)
org.osgi.util.converter.ConverterImpl.loadClassUnchecked(ConverterImpl.java:350)

any idea or is this is bug or a what.

Thanks
Alain


On Mon, Sep 3, 2018 at 6:12 AM Tim Ward  wrote:

>
> Problem 1:
>
> The Relevant bitts of the specification are:
>
> How component properties override each other at runtime:
>
> https://osgi.org/specification/osgi.cmpn/7.0.0/service.component.html#service.component-component.properties
>
> How component properties override each other at build time:
>
> https://osgi.org/specification/osgi.cmpn/7.0.0/service.component.html#service.component-ordering.generated.properties
>
> The sum total of this is that the component properties from the annotation
> that you’ve applied to your component class should come *after* the ones
> from the activate method. There was a very recent fix in Bnd
>  to make sure that this was
> done correctly.
>
>
> Problem 2:
>
> As for your additional issue - A component property type is not a valid
> input for method injection with references. See
> https://osgi.org/specification/osgi.cmpn/7.0.0/service.component.html#service.component-method.injection
>
> You can use the OSGi converter to convert an injected map of properties
> into an instance the annotation if you want.
>
> Best Regards,
>
> Tim
>
> On 25 Aug 2018, at 12:37, Alain Picard  wrote:
>
> I had an idea to try using @ComponentPropertyType and searched and found
> that while not specifically covered by the documentation, in the cpmn there
> is at least one case of a Class property in ExportedService and that the
> code seems to support it
> (ComponentPropertyTypeDataCollector#valueToProperty)
>
> So I went ahead and tried it and it works, but I'm having a more general
> issue with the ComponentProperty type. I am attaching the test project.
>
> The encountered issues are twofold. First what is happening is that the
> values supplied to the annotation are seen in the component, are seen in
> the reference method of the using service, but not in its activate method,
> where I get the default values from the annotation. Second, my service that
> references the one annotated with my component annotation won't start if I
> use a method signature that references the annotation type instead of using
> a map.
>
> Please enlighten me.
>
> Alain
>
>
> On Fri, Aug 24, 2018 at 5:52 AM Tim Ward  wrote:
>
>> Right, so in this case it looks like you’re running a whiteboard, is it
>> possible you would be better off not using the service properties for this
>> filtering? For example:
>>
>> @Reference(policy=DYNAMIC, cardinality=MULTIPLE)
>> private final List renderers = new CopyOnWriteArrayList<>();
>>
>> public ZKRenderer getRendererFor(Object o) {
>> return renderers.stream()
>> .filter(r -> r.supports(o))
>> .collect(Collectors.maxBy((a,b) ->
>> a.getPriority(o).compareTo(b.getPriority(o
>> .orElseThrow(() -> new IllegalArgumentException("No renderer 

Re: [osgi-dev] Retrieving service configuration implementation in reference method

[Tim Ward via osgi-dev]

Problem 1:

The Relevant bitts of the specification are:

How component properties override each other at runtime:
https://osgi.org/specification/osgi.cmpn/7.0.0/service.component.html#service.component-component.properties
 


How component properties override each other at build time:
https://osgi.org/specification/osgi.cmpn/7.0.0/service.component.html#service.component-ordering.generated.properties
 


The sum total of this is that the component properties from the annotation that 
you’ve applied to your component class should come *after* the ones from the 
activate method. There was a very recent fix in Bnd 
 to make sure that this was done 
correctly.


Problem 2:

As for your additional issue - A component property type is not a valid input 
for method injection with references. See 
https://osgi.org/specification/osgi.cmpn/7.0.0/service.component.html#service.component-method.injection
 


You can use the OSGi converter to convert an injected map of properties into an 
instance the annotation if you want.

Best Regards,

Tim

> On 25 Aug 2018, at 12:37, Alain Picard  wrote:
> 
> I had an idea to try using @ComponentPropertyType and searched and found that 
> while not specifically covered by the documentation, in the cpmn there is at 
> least one case of a Class property in ExportedService and that the code seems 
> to support it (ComponentPropertyTypeDataCollector#valueToProperty)
> 
> So I went ahead and tried it and it works, but I'm having a more general 
> issue with the ComponentProperty type. I am attaching the test project.
> 
> The encountered issues are twofold. First what is happening is that the 
> values supplied to the annotation are seen in the component, are seen in the 
> reference method of the using service, but not in its activate method, where 
> I get the default values from the annotation. Second, my service that 
> references the one annotated with my component annotation won't start if I 
> use a method signature that references the annotation type instead of using a 
> map. 
> 
> Please enlighten me.
> 
> Alain
> 
> 
> On Fri, Aug 24, 2018 at 5:52 AM Tim Ward  > wrote:
> Right, so in this case it looks like you’re running a whiteboard, is it 
> possible you would be better off not using the service properties for this 
> filtering? For example:
> 
> @Reference(policy=DYNAMIC, cardinality=MULTIPLE)
> private final List renderers = new CopyOnWriteArrayList<>();
> 
> public ZKRenderer getRendererFor(Object o) {
> return renderers.stream()
> .filter(r -> r.supports(o))
> .collect(Collectors.maxBy((a,b) -> 
> a.getPriority(o).compareTo(b.getPriority(o
> .orElseThrow(() -> new IllegalArgumentException("No renderer for 
> object " + o));
> }
> 
> Tim
> 
>> On 24 Aug 2018, at 10:34, Alain Picard > > wrote:
>> 
>> They represent classes, which is why I would have like to have a Class 
>> annotation so I could do "tester=MyTester.class". instead of 
>> "tester="com.acme.mypkg.MyTester". 
>> 
>> For example I have a number of components implementing a service and as part 
>> of their property they define their "filter conditions" which are then 
>> passed on to the 3rd party library, and there are 2 types of testers, etc:
>> Component(service=ZKRenderer.class, factory=ZKRenderer.CONFIG_FACTORY,
>>   property= { ZKRenderer.CONFIG_STATIC_TEST + "=c.c.i.tester.ReferenceTree", 
>>   ZKRenderer.CONFIG_STATIC_TEST_PRIORITY + ":Integer=9" })
>> 
>> If I move my ReferenceTree tester in the above case, no compiler would catch 
>> it and I'm just looking for pain in the future. 
>> 
>> I am not sure I grasp your approach. Here clients just ask for a renderer 
>> (an instance of the service) for some "object" that is passed in and an 
>> appropriate and "highest ranking" one is returned. So the client is never 
>> specifying the class string at all. Here we are providing the full class 
>> name so it can be loaded, hence it would be much more natural to provide a 
>> Class object. 
>> 
>> When we have cases where the component and reference must have to match we 
>> do as such:
>> public static final String CONFIG_QUALIFIER = 
>> OsgiConstants.SERVICE_QUALIFIER + "=ReferenceList"; //$NON-NLS-1$
>> public static final String CONFIG_TARGET = "(" + CONFIG_QUALIFIER + ")"; 
>> //$NON-NLS-1$ //$NON-NLS-2$
>> 
>> and here the component use the 1st line in its property and the reference 
>> target uses the 2nd constant and that is not an issue.
>> 
>> Alain
>> 
>> 
>> 
>> Alain Picard
>> Chief Strategy Officer
>>