1. An image forming apparatus for executing a processing flow including a plurality of steps, said apparatus comprising: one or more processing devices; and one or more memory devices communicatively connected to the one or more processing devices and storing instructions configured to be executed by the one or more processing devices, the instructions comprising instructions for: acquiring definition information of the processing flow; identifying, if a step to be executed by the image forming apparatus in the processing flow is an instruction-required step as determined by reference to the definition information, a user required to complete the instruction-required step; displaying a first operation window on a display unit of the image forming apparatus, the first operation window configured to receive an instruction from the user at the image forming apparatus to complete the instruction-required step; measuring a duration of a waiting period where the instruction has not been received via the first operation window; if the duration of the waiting period exceeds a predetermined time period, (a) determining a pre-registered remote notification address for the user, and (b) transmitting remote execution information to the pre-registered remote notification address, the remote execution information configured to cause a second operation window to be displayed on a display unit of a remote device that is remote from the image forming apparatus, and the second operation window configured to receive the instruction from the user at the remote device to remotely complete the instruction-required step to be executed by the image forming apparatus; and if a particular step to be executed by the image forming apparatus in the processing flow is not the instruction-required step as determined by reference to the definition information, controlling execution of the particular step without displaying the first operation window and without transmitting the remote execution information.