For individual developers, Postbacks over WebSocket is recommended, where, orders placed for a particular user anywhere, for instance, web, mobile, or desktop platforms, are sent.
No, you can't use the publisher to modify or cancel the order. Modify or cancel orders require order_id as input param and you can use only these sets of input params for the publisher.
We don't recommend high-frequency polling positions. Depending on your requirement, you can make use of Websocket streaming, post-back, order-book APIs, etc to work around instead of polling positio…