What is a conversation?

There are surely many ways to look at "what is a conversation?" One would be from the outside where you classify conversation modes into "harmonious" or "discordant". Another might be to acknowledge that different conversational roles are possible for the conversants. So free-form discussion between "equals" is different from instruction from teacher to pupil, or from boss to assistant.

Perhaps a flaw in generic chatbot thinking is that no such role definition is needed, or that discussion between equals is the correct default. But for a good order chat bot, my vision is that it is taking instructions from the boss, asking intelligent questions, and offering helpful reminders and suggestions. But it does not need any more of an agenda than to keep the discussion focused on an order being completed and moving forward.
Update: Another conversational mode is where two people share an agreement - whether about something they observe together, or something they speculate on - painting pictures for each other.