Console calling OSGi bundle returns “cannot be cast to…”

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I have 2 bundles, one that supplys a service and the other that calls the
service. When both are installed and started in felix framework everything
works.

Now, I would like to drop/forget the client bundle and create a console app
to launch felix, install server bundle and call the service.



Here the structure of server bundle (MyBundleServer):

Src

   com.mycompany.mybundleserver package

      Activator.java

      upnpImpl.java

   com.mycompany.mybundleserver.serviceinterface

      upnp.java   -> the interface



For the console client, I created a java application, I added the
org.apache.felix.framework-2.0.0.jar and wrote the following code in main()
function


 FrameworkFactory frameworkFactory =
ServiceLoader.load(FrameworkFactory.class).iterator().next();

Map<String, String> config = new HashMap<String, String>();

Framework framework = frameworkFactory.newFramework(config);

framework.start();


BundleContext context = framework.getBundleContext();

Bundle y=
context.installBundle("file:/C:/OSGi/felix-framework-4.0.3/MyBundleServer-1.0-SNAPSHOT.jar"
); //the server bundle

y.start();



ServiceReference sr  =  context.getServiceReference(upnp.class.getName());

 if(sr != null)

 {

          upnp x = (upnp)context.getService(sr); //interface type

          if(x != null)

          {

                int n=x.GetNumber();

                context.ungetService(sr);

          }

   }



When running, line

upnp x = (upnp)context.getService(sr);

generates:

Exception in thread "main" java.lang.ClassCastException:
com.mycompany.mybundleserver.upnpImpl cannot be cast to
com.mycompany.mybundleserver.serviceinterface.upnp

at mystandaloneclient.MyStandAloneClient.main(MyStandAloneClient.java:65)



So, if upnpImpl implements upnp interface and upnp is the interface why can
not JVM cast this stuff?

Thanks a lot



Alex