Echo

In a distributed system it may be difficult to deduce which event occurred when. But the database is the final point of certainty. Therefore, we can surely say that if a database transaction is completed successfully the event is actually occurred at the transaction execution.

If a user completes an action successfully, some database table will get updated. For example if user sends a withdrawal request, some table in database will have a record that contain the withdrawal request details.

To notify the user in realtime with absolute certainty, these data changes are published via pg_notify to z_event_stream channel and echo will capture these changes.

Database messages

Pg_notify messages have following fields.

Field	Type	Desc
e_id	number	Global private event id
e_ts	number	Event timestamp in ms
e_src	string	Event code
e_user	number	User id
e_detail	json	Event details

Published messages

Echo will reformat received messages in a more friendly way and publish the reformatted messages via websocket.

{
  "event": "user",
  "ts": 1757491799565,
  "eid": 64460367,
  "user_id": 2801682,
  "data": {
    "levelId": [
      3,
      3
    ],
    "status": [
      0,
      0
    ],
    ...
  }
}

Published messages will be captured from socket relay project as private events and socket relay will publish the event details to users' private socket channel.