This moves the entire clearing system to use typed messages using
`pydantic.BaseModel` such that the streamed request-response order
submission protocols can be explicitly viewed in terms of message
schema, flow, and sequencing. Using the explicit message formats we can
now dig into simplifying and normalizing across broker provider apis to
get the best uniformity and simplicity.
The order submission sequence is now fully async: an order request is
expected to be explicitly acked with a new message and if cancellation
is requested by the client before the ack arrives, the cancel message is
stashed and then later sent immediately on receipt of the order
submission's ack from the backend broker. Backend brokers are now
controlled using a 2-way request-response streaming dialogue which is
fully api agnostic of the clearing system's core processing; This
leverages the new bi-directional streaming apis from `tractor`. The
clearing core (emsd) was also simplified by moving the paper engine to
it's own sub-actor and making it api-symmetric with expected `brokerd`
endpoints.
A couple of the ems status messages were changed/added:
'dark_executed' -> 'dark_triggered'
added 'alert_triggered'
More cleaning of old code to come!
Tyler Goodlet