It is very common to have an Iterator drive the AssemblyLine.
The most common pattern for using a Connector in Iterator mode is:
These mapped Attributes are retrieved from the data source, placed in the Work entry, and passed to the Connectors in the Flow section in the AssemblyLine.
If you did not create the Connector directly inside an AssemblyLine, then in order to use this Connector in an AssemblyLine, drag the Connector from its location in <workspace>/Resources/Connectors to the Feed section of an AssemblyLine.
Parent topic: Iterator mode