On 9 Dec 2016, at 06:43, ??? (Uze Choi) <uzchoi at samsung.com> wrote: > > Presumably, When client with updated protocol want to communicate with > server, server can detect client protocol is new one.
How does the behavior of the server change based on this information? What happens if the server does not know about the new protocol version? (If the behavior change is mandatory, the new client cannot interoperate with the older server.) The client request will need to make sense for servers implementing previous protocol versions. (If you don?t do that, clients cannot really use new protocol versions, because they might be running into older version servers.) This means the protocol version cannot really supply any crucial information. So, in summary, version numbers are great for making sure that a newer client does not interoperate with an older server (yes, that may sometimes be an objective). But they are not very good for evolving a protocol in a backwards-compatible way, which is what you?ll want to do in most cases. Gr??e, Carsten
