设计问题:消息处理组件..调用不正确的重载函数

我正在写一个消息处理程序。主要组件是接收器、处理器、过滤器、翻译器和发送器。我希望在处理器组件的"进程"功能上有一个单点故障，用于捕获异常、日志记录和度量

正下方是控制台输出，显示出我有点过头了。

BASE
A
B
A

---FILTER---
FILTERED BASE
DID NOT FILTER A
Looks like a B     <------THIS IS WHAT I WANT
DID NOT FILTER B

---PROCESS---
FILTERED BASE
DID NOT FILTER A
DID NOT FILTER B   <-----THIS MAKES ME SAD

这些是类别定义

#include <string>
#include <iostream>
#include <memory>
//**************MESSAGES ************************
class Message
{
public:
    virtual std::string getOut() const {return std::string("BASE");};
};
class MsgA : public Message
{
public:
    std::string getOut() const {return std::string("A");};
};
class MsgB : public Message
{
public:
    std::string getOut() const {return std::string("B");};
};

//**************FILTERS ************************
class MsgFilter
{
public:
    void filter(const std::tr1::shared_ptr<Message> msg)
    {
        if( msg->getOut().compare("BASE") == 0 )
        {
            std::cout << "FILTERED BASE" << std::endl;
        }
        else
        {
            std::cout << "DID NOT FILTER " << msg->getOut() <<  std::endl;
        }
    }
    void filter(const std::tr1::shared_ptr<MsgB> msg)
    {
        std::cout << "Looks like a B" << std::endl;
        filter((std::tr1::shared_ptr<Message>)msg);
    }
};
//**************PROCESSORS ************************
class MsgProcessor
{
public:
    MsgProcessor():myFilt(MsgFilter()){}
    MsgFilter myFilt;
    virtual void process(std::tr1::shared_ptr<Message> msg)
    {
        myFilt.filter(msg);
    }
};

以下是的主要功能

#include "AllClassDefs.h"
int main(int argc, char *argv[])
{
    std::tr1::shared_ptr<Message> msg(new Message());
    std::tr1::shared_ptr<MsgA> msgA(new MsgA());
    std::tr1::shared_ptr<MsgB> msgB(new MsgB());
    std::cout << msg->getOut() << std::endl;
    std::cout << msgA->getOut() << std::endl;
    std::cout << msgB->getOut() << std::endl;
    std::tr1::shared_ptr<Message> msgAPtr(msgA);
    std::cout << msgAPtr->getOut() << std::endl;
    std::cout <<"nnFILTER---n";
    std::tr1::shared_ptr<MsgFilter> flt(new MsgFilter());
    flt->filter(msg);
    flt->filter( (std::tr1::shared_ptr<Message>) msgA);
    flt->filter(msgB);
    std::cout <<"nnPROCESS---n";
    std::tr1::shared_ptr<MsgProcessor> prc(new MsgProcessor());
    prc->process(msg);
    prc->process(msgA);
    prc->process(msgB);
}

所以。。。我希望进程函数调用Filter(MsgB(函数，而不是Filter(Message(函数。通过使用process(Message(函数，看起来Filter将MsgB视为Message。我怎样才能让它正常工作？
我知道我可以使用模板，但这似乎有点过头了。。。另外，在一个有几百个消息类的系统中，它可能会导致一个大的exe。我应该使用双重调度吗？或者有更简单的解决方案吗？