How to reference a domain component (DC) from an XPO business class and vice versa

Hello Trentin,
>>
The problem is that I now cannot use Domain Components because the Contact persistent object cannot reference the domain components.
<<
To implement a reference to the DC interface in a regular business object, declare a hidden property of the Guid type mapped to a foreign key column and implement the IObjectSpaceLink interface. The IObjectSpace component is necessary to manage DC objects, which cannot be managed using the Session component.

Here is the code snippet demonstrating the implementation details.

C#
[NavigationItem]  
[DomainComponent]  
public interface TestInterface {  
    string Name { get; set; }  
}  

[DefaultClassOptions]  
public class TestClass : BaseObject, IObjectSpaceLink {  
    public TestClass(Session session) : base(session) { }  
    private TestInterface fRef;  
    [PersistentAlias("[Alias_Ref]")]  
    public TestInterface Ref {  
        get {  
            if (fRef == null && Alias_Ref.HasValue) {  
                fRef = ObjectSpace.GetObjectByKey<TestInterface>(Alias_Ref.Value);  
            }  
            return fRef;  
        }  
        set {  
            fRef = value;  
            if (value == null) {  
                Alias_Ref = null;  
            } else {  
                Alias_Ref = (Guid)ObjectSpace.GetKeyValue(value)  
            }  
        }  
    }  
    [Persistent("Ref")]  
    [Browsable(false)]  
    public Guid? Alias_Ref {  
        get { return GetPropertyValue<Guid?>("Alias_Ref"); }  
        set { SetPropertyValue("Alias_Ref", value); }  
    }  

    public IObjectSpace ObjectSpace { get; set; }  
}  

Take special note that if you do not need all this code if you want to reference an XPO class from a domain component - simply declare a regular property in your interface as follow:

C#
[DomainComponent]  
public interface TestInterface2 {  
    MyXpoClassType XpoReference { get; set; }  
}  

True associations like between regular XPO models are not possible.
However, it is possible to declare a weak IList<YourPersistentType> YourCollection {get;} property and return a required collection from the Get_YourCollection method of a domain logic class. You can do this via the IObjectSpace.GetObjects method.

I want to again emphasize that this scenario is a bit unnatural as domain components were not designed to be mixed with XPO models by default. These solutions (not very straightforward) are possible only because DC models are generated into XPO models at runtime. I would not recommend you use such mixing in many places of your app as it is recommended to go either with XPO or with DC without mixing.
I hope you find this information helpful.
See Also:
Security - Support domain components in the new security system (Client-Side UI and Integrated modes)
Custom "Improved Security" Users, Roles, and Permissions using Domain Components
Domain Components - Persistent Interfaces - Help
Thanks,
Dennis

I have dealt with this by registering the Domain Component with the SecuritySystemUser class (or SecurityStrategy) as base class.
I attach an example solution.

PS: Yeah, I know that the question is a bit old, but I wanted to share my solution in case someone is having the same problem today.