OK - I admit in do not get it and I need a good sample
I have 2 interfaces IProduct and ISupplier
There are 2 implementation ProductImpl and SupplierImpl

public inteface IProduct {
public Supplier getSupplier();
public void setSupplier(Supplier s);
}
public inteface ISupplier {
public Set getProducts();
public void setProducts(Set s); // this seems to be needed :-(
}
and then ProductImpl implements IProduct
and then SupplierImpl implements ISuppier

<hibernate-mapping>
<class name="com.microsoft.northwind.impl.ProductImpl" table="Products" >
<id name="ProductID" type="int" unsaved-value="null" >
<column name="ProductID" sql-type="int identity" not-null="true" />
<generator class="hilo" />
</id>
<many-to-one name="Supplier" column="SupplierID" not-null="false" />
</class>
<class name="com.microsoft.northwind.impl.SupplierImpl" table="Suppliers" >
<id name="SupplierID" type="int" unsaved-value="null" >
<column name="SupplierID" sql-type="int identity" not-null="true" />
<generator class="hilo" />
</id>
<set name="Products" table="Products" inverse="true" cascade="all" >
<key column="SupplierID" />
<one-to-many class="com.microsoft.northwind.ISupplier" />
</set>
</class>
</hibernate-mapping>
gives Association references unmapped class: com.microsoft.northwind.Supplier
I tried overriding configuration to 'correct' the issue but the error is in the final Binding class :-(

So i tried to use the Interface with a custom persistor which overeides instantiate to return the implementation
<!--persister="com.babel17.persistor.FrameworkPersister" >
<hibernate-mapping>
<class name="com.microsoft.northwind.IProduct" table="Products" persister="com.babel17.persistor.FrameworkPersister" >
<id name="ProductID" type="int" unsaved-value="null" >
<column name="ProductID" sql-type="int identity" not-null="true" />
<generator class="hilo" />
</id>
<many-to-one name="Supplier" column="SupplierID" not-null="false" />
</class>
<class name="com.microsoft.northwind.ISupplier" table="Suppliers" persister="com.babel17.persistor.FrameworkPersister" >
<id name="SupplierID" type="int" unsaved-value="null" >
<column name="SupplierID" sql-type="int identity" not-null="true" />
<generator class="hilo" />
</id>
<set name="Products" table="Products" inverse="true" cascade="all" >
<key column="SupplierID" />
<one-to-many class="com.microsoft.northwind.ISupplier" />
</set>
</class>
</hibernate-mapping>
Now the correct class is build by FrameworkPersister
but in loadFromResultSet I get
No persister for: com.microsoft.northwind.impl.ProductImpl
at net.sf.hibernate.impl.SessionFactoryImpl.getPersister(SessionFactoryImpl.java:344)
at net.sf.hibernate.impl.SessionImpl.getClassPersister(SessionImpl.java:2656)
at net.sf.hibernate.impl.SessionImpl.getPersister(SessionImpl.java:2663)
at net.sf.hibernate.loader.Loader.loadFromResultSet(Loader.java:544)

I have posted to the forum before and have recieved replies which are prompt but one sentence like
use the implementation -
All I want is apointer to a piece of sample code which actually enables me to treat my properties as
interfaces or just explain any solution short of implimenting the properties as implementations not interfaces - Help

There's this really great feature on this board to actually format code ;)

In the mapping you need to specificy the class, not the impl. In the class, simply specify the interface for the association. This is normal java semantics, a class is always castable to any interfaces it implements.

So, do: