Data Node
Data handles reads and writes, such as creating, querying, updating, deleting, or aggregating data. It is used inside domain services so the outer flow does not operate on the database directly.
Guide
For example, after reimbursement validation passes, the system saves the reimbursement record to the database.
It can also query order details by order number, or update a user status to “verified”.
You can understand it as: the step that actually touches the database.