I am still not sure whether the title of my question is correct and it most probably is not. However I have spent some time searching both the net and stackoverflow and I can not find a good description of the issue I am facing.

Basically what I want to achieve is the ability to read some raw bytes and based on the value of some of them to interpret the rest in different ways. This is how TLV works in a way, you check the tag and depending on it - interpret the result. Of course I can always keep that logic in my C++ code, however I am looking for a solution which would move the logic out of the source code (maybe to some xml description). This would allow me to describe different encodings (protocols) more easily. I am familiar with Protocol Buffers and some other serialization libraries, however all of them solve different issue. They assume they are on both ends of the communication, while I want to describe the communication (sort of).

Is such solution available, if no - why not? Are there some inherent difficulties I will face trying to implement it.