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Date: Sun, 13 Sep 2009 15:17:51 +0200
From: Kadir Alaca <alaca@web.de>
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To: users@jackrabbit.apache.org
Subject: Programming against interfaces and @Bean-Fields
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Sender: alaca@web.de

Hi,

i have an interface IMyImage and its implementation in MyImageImpl.
MyImageImpl has @Bean-Fields which refer to the interface IMyResource.
IMyResource is implemented in MyResourceImpl.

But here the related code:


@Node(isInterface=true, jcrType="my:bag", discriminator=false)
public interface IMyBag {
    //getter and setter defs for path, uuid and other
}

@Node(isInterface=true, jcrType="my:image", extend=IMyBag.class, 
discriminator=false)
public interface IMyImage extends IMyBag {
    IMyResource getImage();
    void setImage(IMyResource resource);
    //...
}

@Node(isInterface=true, jcrType="my:resource", discriminator=false)
public interface IMyResource {
    InputStream getData();
    void setData(InputStream data);
    //...
}

@Node(jcrType="my:bagimpl", isAbstract=false, discriminator=false)
@Implement(interfaceName=IMyBag.class)
public class MyBagImpl implements IMyBag {
    @Field(path = true)
    private String path;

    @Field(uuid=true)
    private String UUID;
    //...
}

@Node(jcrType="my:imageimpl", extend=MyBagImpl.class, discriminator=false)
@Implement(interfaceName=IMyImage.class)
public class MyImageImpl extends MyBagImpl implements IMyImage {
    @Bean(jcrName="my:image", proxy=true, 
converter=DefaultBeanConverterImpl.class)
    protected IMyResource image;

    public IMyResource getImage() {
        return image;
    }

    public void setImage(IMyResource image) {
        this.image = image;
    }
    //...
}

@Node(jcrType="my:resourceimpl", isAbstract=false, discriminator=false)
@Implement(interfaceName=IMyResource.class)
public class MyResourceImpl implements IMyResource {

    @Field(jcrName="my:binarydata")
    protected byte[] binarydata;

    public byte[] getBinarydata() {
        return binarydata;
    }

    public void setBinarydata(byte[] binarystream) {
        this.binarydata = binarystream;
    }

    public InputStream getData() {
        return new ByteArrayInputStream(this.binarydata);
    }

    public void setData(InputStream data) {
            this.binarydata = FileUtils.toByteArray(data);
    }
    //...
}


When i insert such an image, OCM works pretty fine.
Applying an update on that inserted image results to the following 
exception:

Repository access exception; nested exception is 
org.apache.jackrabbit.ocm.exception.IncorrectPersistentClassException: 
Class of type: java.lang.Object has no descriptor.
org.springmodules.jcr.JcrSystemException: Repository access exception; 
nested exception is 
org.apache.jackrabbit.ocm.exception.IncorrectPersistentClassException: 
Class of type: java.lang.Object has no descriptor.

I have debugged OCM and found that

    public static Class getBeanClass(Object bean)
    {
         Class beanClass = bean.getClass();
         if (isProxy(beanClass))
         {
                 //CGLIB specific
                 return beanClass.getSuperclass();
         }
         return beanClass;
    }

in org.apache.jackrabbit.ocm.reflection.ReflectionUtils returns
java.lang.Object
for the field
protected IMyResource image;

The return value is used in ObjectConverterImpl to retrieve the 
ClassDescriptor for the Bean:
ClassDescriptor classDescriptor = 
mapper.getClassDescriptorByClass(ReflectionUtils.getBeanClass(object));

Of course there is no descriptor for java.lang.Object.

When i implement the same structure with concrete classes, OCM works fine.

The relevant technology-stack:
+ jackrabbit 1.6.0 with ocm 1.5.3
+ spring 2.5.6
+ springmodules 0.9 - with patch from 
http://jira.springframework.org/browse/MOD-446
+ tomcat 6.0.18
+ cglib


How can i improve my code or maybe OCM self to get done the update-thing 
with interfaces?

Any advice is welcome.

Thanks in advance,
Kadir.