Question

I have built a Python server to which various clients can connect, and I need to set a predefined series of messages from clients to the server – For example the client passes in a name to the server when it first connects.

I was wondering what the best way to approach this is? How should I build a simple protocol for their communication?

Should the messages start with a specific set of bytes to mark them out as part of this protocol, then contain some sort of message id? Any suggestions or further reading appreciated.

Answer 1

First, you need to decide whether you want your protocol to be human readable (much more overhead) or binary. If the first, you probably want to use regular expressions to decode the messages. For this, use the python module re. If the latter, the module struct is your friend.

Second, if you are building a protocol that is somehow stateful (e.g. first we do a handshake, then we transfer data, then we check checksums and say goodbye) you probably want to create a some sort of FSM to track the state.

Third, if protocol design is not a familiar subject, read some simple protocol specifications, for example by IETF

If this is not a learning excercise, you might want to build up from something else, like Python Twisted