The Read operation allows for download of data from the FormWork server.
The pipeline of operations triggered once you press the 'read' button is the following:
On Read Click event is run (info on the Events here): with this event the client notifies the server that he wants to read a given form. No data has been sent by the server yet.
Before Read event is run: the server has materialized a table with the data ready to be sent to the client. If you associate a procedure with this event the data to be sent can be modified ad hoc by acting on this table (you can get its name from the GetExecutionReason activity).
Run of the After Read event: the server has sent the data to the client, compensation or logging logics can be insterted.