A feasible solution that has been practiced in work:

1. backend record status (for example, it can be persisted to the database, there is a field called status ), and status indicates the stage of execution, for example, after the B transaction is completed, set this field to B li C transaction, and set this field to C
.
2. the front end sends a request for training the back end every once in a while (the polling interval is determined according to the timeliness requirement. Before a bidding system is made, the polling interval of the front end is 3 seconds). The back end returns the status field in the database, that is, status , and the front end can know which stage it is currently performing
.

if you think this scheme is not very elegant, you can consider websocket

agrees that
one is to use rotational training. The client constantly queries the server about the current progress
has been using persistent connections. When the progress changes, the server will take the initiative to notify the client