Re: Newbie question for ClassCastException

> Great, this was the problem.  My interface was in the same package as the
> implementation and the maven bundle plugin took the liberty to include the
> interface into the jar.
>
> Thanks for the help, it woked first time when I realized this one and
> changed the package name.  Now, I have a second error that I still don't
> know how to solve regarding the system bundle.
>
> I am trying to make a wicket panel into the bundle and include it into the
> main application.  when the bundle is loaded, it give me this error :
>
> Error while starting bundle:
> /C:/java/project/demo-wicket-felix/target/felix/fileinstall/panel1-0.0.1-SNAPSHOT.jar:
> org.osgi.framework.BundleException: Unresolved constraint in bundle 1:
> package; (&(package=org.apache.wicket.ajax)(version>=1.4.0))
>
> To get ride of it, I entered this line in my properties file :
> org.osgi.framework.system.packages.extra=org.apache.wicket;org.apache.wicket.ajax;
> org.apache.wicket.ajax.markup.html; org.apache.wicket.markup.html.basic;
> org.apache.wicket.markup.html.panel; org.apache.wicket.model; version=1.4.0,
> com.mycompany.panel
>
> The problem that I see with that is that everytime the wicket framework get
> updated or the user use something that is unknown to the server in it's
> packages, the line have to be expended.
>
> Is there a patern that can be used in order to make sure this line include
> everything that the server see.  I don't really expect the exports to
> contain everything, but a wildcard like org.apache.wicket.* could be used
> instead to make it easier to manage.
>
> I hope I'm getting clear.  If any of you need more information, just ask and
> it will be my pleasure to give it back.
>
> Marc-Andre
>
>
> On Thu, Jun 18, 2009 at 11:04 AM, Richard S. Hall<heavy@...>wrote:
>
>    
>> If you are creating an embedded instance of Felix and trying to use
>> services from bundles inside of Felix on the outside in your host
>> application, then you have to make sure there is only one copy of the
>> service interface class and everyone is using it. Typically this is done by
>> putting them on the class path and exporting them via the system bundle.
>> Check:
>>
>>
>> http://felix.apache.org/site/apache-felix-framework-launching-and-embedding.html
>>
>> ->  richard
>>
>>
>> On 6/18/09 10:42 AM, Marc-Andre Houle wrote:
>>
>>      
>>> I'm sure I am presently asking a really simple question that have been
>>> seen
>>> a thousand times.  But since I don't know where to start with OSGI, I'll
>>> ask
>>> the question here in hope that one person would help me.
>>>
>>> We need to build a plugin management for a web application running wicket.
>>> It is already running and I would want to include OSGI bundle
>>> extendability.  I want bundles that are added to register as services in
>>> order to give access to some methods.  The bundle is installed in felix
>>> using the FileInstall activator.  I will not paste all the code since I
>>> think the interface and implementation is irrelevant here. (Even if they
>>> are
>>> really simple).  The problem come with the fact that I cannot cast the
>>> service received into the interface implemented.  I get a
>>> ClassCastException
>>> when trying to use it.
>>>
>>> Here is the code at initialization of the web application :
>>> //Make the felix startup here.
>>>          Properties felixProps = new Properties();
>>>          try {
>>>
>>> felixProps.load(this.getClass().getResourceAsStream("/felix.properties"));
>>>          } catch(Exception e) {
>>>              logger.warn("Could not load felix properties", e);
>>>          }
>>>
>>>          List<BundleActivator>   list = new ArrayList<BundleActivator>();
>>>
>>>          FileInstall activator = new FileInstall();
>>>          list.add(activator);
>>>
>>>          this.panelProvider = new PanelServiceProvider();
>>>          list.add(this.panelProvider);
>>>
>>>          felixProps.put(FelixConstants.SYSTEMBUNDLE_ACTIVATORS_PROP, list);
>>>          try {
>>>              this.felix = new Felix(felixProps);
>>>              this.felix.start();
>>>              logger.info("Felix started.");
>>>          } catch(Exception ex) {
>>>              logger.error("Could not load felix", ex);
>>>          }
>>>
>>> Here is the code for the PanelServiceProvider class :
>>> public class PanelServiceProvider implements BundleActivator {
>>>
>>>      private ServiceTracker serviceTracker;
>>>      public void start(BundleContext context) throws Exception {
>>>          this.serviceTracker = new ServiceTracker(context,
>>> PanelDescriptor.class.getName(), null);
>>>          this.serviceTracker.open();
>>>      }
>>>      public void stop(BundleContext arg0) throws Exception {
>>>          this.serviceTracker.close();
>>>      }
>>>
>>>      public List<PanelDescriptor>   getAllPanelDescriptor(){
>>>          if(this.serviceTracker != null){
>>>              Object[] services = this.serviceTracker.getServices();
>>>              if(services != null){
>>>                  List<PanelDescriptor>   panels = new
>>> ArrayList<PanelDescriptor>(services.length);
>>>                  for(Object service : services){
>>>                      if(service instanceof PanelDescriptor){
>>>                          panels.add((PanelDescriptor)service);
>>>                      }else{
>>>                          System.out.println("Unknown service : " +
>>> service.getClass().getName());
>>>                          for(Type type :
>>> service.getClass().getGenericInterfaces()){
>>>                              System.out.println("Implementing : " +
>>> type.toString());
>>>                          }
>>>                      }
>>>                  }
>>>                  return panels;
>>>              }
>>>          }
>>>          return null;
>>>      }
>>> }
>>>
>>> And here is the result that I get for invoking this method when I call the
>>> page in the web app :
>>>
>>> Installed
>>>
>>> c:\java\project\demo-wicket-felix\target\felix\fileinstall\panel1-0.0.1-SNAPSHOT.jar
>>> 2009-06-18 10:18:34.544::INFO:  Started
>>> SelectChannelConnector@...:8080
>>> [INFO] Started Jetty Server
>>> Unknown service : com.mycompany.panel.PanelDescriptorImpl
>>> Implementing : interface com.mycompany.panel.PanelDescriptor
>>>
>>>
>>> What that mean is that the serive is loaded, it can be reached, but the
>>> classes does not come from the same classloader.  Now, I'm a little lost
>>> as
>>> to what I'm supposed to do in this case.Does anybody have an idea on what
>>> I
>>> could do to solve this problem?
>>>
>>> If more details is needed (Like the manifest files or the other classes),
>>> let met know and I'll provide them.
>>>
>>> Thanks in advance.
>>>
>>> Marc-Andre
>>>
>>>
>>>
>>>        
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