How Protocol buffer interact with legacy protocol code

every one, I have a question about how protocol buffer interact with existed protocol mechanism,Say code below:

class PacketBase
{
pub开发者_如何转开发lic:
   PacketBase();
private:
   int msgType;
   int msgLen;
private:
   MessageBuilder* m_pMsgBuilder;   /// do Write and Read From msg stream

};

class LoginRequest : public PacketBase
{
 /// here we can use proto replace the msg field defined here
 /// invoke write or read method in packetbase to serialze or de-serialize
};

Can protocol buffer do the job while maintain the class hierarchy unchanged?

---

Well, since your msgType and msgLen fields are both private, I think your question boils down to "Can I replace LoginRequest with a protocol buffer that has a no-args constructor?" and the answer here is an unqualified "yes".

Protocol buffers take care of (de-)serializing fields while maintaining type information; there's really no reason for you to write that code yourself. If you were to create a LoginRequest protobuf, for example, you could just construct it, call setters to set its fields, and then serialize it to an ostringstream. That's probably sufficient for what you want, right?