Generic message factory or ...

Consider the pseudo code.

Code:

---


class Base_Msg {
public:
  // stuff
  virtual ~Base_Msg() {}
};
class X1_Msg : public Base_Msg {
public:
  // stuff
};
// more Xn messages
class V1_Msg : public Base_Msg {
public:
  // stuff
};
// more Vn messages


//later
class EvDelegate {
public:
  virtual void Do_Work() = 0 ;
};

// from Client
class X1 : public EvDelegate {
  X1_Msg x1Obj ;
public :
  void ProcessMsg ( char *ptrBuf )
  {
    EvManager::Instance().Notify ( x1Obj ) ;
    //if ( v1Obj.Get_XXX_Status () ) {
    //}
  }
};

// to Client
class V1 : public Listener< X1_Msg > {
  V1_Msg v1Obj ;
public :
  V1()
  {
    EvManager::Instance().Register ( X1_Msg ) ;
  }
  void OnEvent ( X1_Msg& x1 )
  {
  //if ( x1.Get_Whatever () == SOME_VALUE )
  //{
  //  v1Obj.Set_Something_Else ( ... )
  //}
  }
  // called from Servers
  void Update ( XYZ_Status *subject )
  {
    // v1Obj.Set_Another_Thing ( subject->Value1  ) ;
    //etc
  }
};


class V2
{
  V2_Msg v2Obj ;
public :
  V2() {} //no need to 'Register' to any Xn message

  // called from Servers
  void Update ( ABC_Status *subject )
  {
    // v2Obj.Set_Whatever ( subject->Value1  ) ;
    //etc
  }
};

---

Incoming data (read) from 'Clients' get processed via the ProcessMsg member function within the appropriate Xn class. The registered Vn class is notified of the 'updated' Xn_Msg.

Outgoing data (writes) to Client is handled via the Vn class. Vn_Msg message updates (from Server side) occurs through the Update method.

Vn class registration is on a 'if needed' basis. For instance: The V2 class has no interest in an Xn_Msg.

At issue: An X1 class needs access to a v1Obj (V1_Msg). Here again not all Xn classes need access to Vn_Msg objects.

My current thought is to create a 'message repository' where interested Xn classes and Vn classes could query for the appropriate Xn_Msg or Vn_Msg. I've scanned the GOF for alternative patterns/ideas that would work well here but I'm at a loss. Ideas welcomed. Thanks in advance