ComServer that should return a ComObject

Question

What I am trying to do is transfer an object that has been created on the serverside to the client. I have got it to work well when I using c++ on both server and client side, but I do not get my server to work correct with other languages like .Net, It probably doesn't like the pointers!

Does this Serversidecode look correct?

Server Form: .h

class TForm2 : public TForm
{
__published:      // IDE-managed Components
      TMemo *Memo1;
private:      // User declarations
      DummyComObj* formDummy;
public:            // User declarations
      __fastcall TForm2(TComponent* Owner);
      IDummyComObj* Getformdummy();
};

.cpp

__fastcall TForm2::TForm2(TComponent* Owner)
      : TForm(Owner)
{
      CoCreateInstance( CLSID_DummyComObj,NULL,CLSCTX_ALL,IID_IDummyComObj,(void**)&formDummy);
}

DummyComObj* TForm2::Getformdummy()
{
      return formDummy;
}

Server TestComServerImpl: .cpp

STDMETHODIMP STDMETHODCALLTYPE TServerDidleComTestImpl::GetMyObject(IDummyComObj** outObj)
{
      DummyComObj *myDum = Form2->Getformdummy();
      *outObj = &myDum;
      return S_OK;
}

Answer 1

Your GetMyObject() method is bad, it returns a pointer to a local variable. That will only work by accident, never for any language that wraps COM. Fix (minus error handling):

DummyComObj *myDum = Form2->Getformdummy();
return myDum->QueryInterface(__uuidof(IDummyComObj), outObj);

Not sure if __uuidof() is available in Builder, use whatever you got to get the IID of the interface.

Answer 2

Asside from TServerDidleComTestImpl::GetMyObject() not compiling due to you trying to assign a DummyComObj ** to a DummyComObj*, but you are also completely ignoring COM reference counting rules.

Try this instead:

Server Form: .h

#include <utilcls.h>

class TForm2 : public TForm
{
__published: // IDE-managed Components
    TMemo *Memo1;
private: // User declarations
    TComInterface<IDummyComObj> formDummy;
public: // User declarations
    __fastcall TForm2(TComponent* Owner);
    void Getformdummy(IDummyComObj** outObj);
};

Server Form: .cpp

__fastcall TForm2::TForm2(TComponent* Owner)
    : TForm(Owner)
{
    CoCreateInstance( 
CLSID_DummyComObj,NULL,CLSCTX_ALL,IID_IDummyComObj,(void**)&formDummy);
}

HRESULT TForm2::Getformdummy(DummyComObj** outObj)
{
    return formDummy->QueryInterface(IID_IDummyComObj,(void**)outObj);
}

Server TestComServerImpl: .cpp

STDMETHODIMP STDMETHODCALLTYPE 
TServerDidleComTestImpl::GetMyObject(IDummyComObj** outObj)
{
    return Form2->Getformdummy(outObj);
}