Realtime interface between mainframe and SAP

We are trying to determine the best way to send data from our mainframe to our sap system which will then call a bapi (or something). The mainframe data will be entered by users multiple times throughout the day. We would like this to be realtime so that when they finish entering the data in the mainframe, the data will be sent to SAP to process the data within SAP.

I've read about LSMW but it seems like it shouldn't be used with the frequency of the data that we will be creating. We have thought about storing the data in mainframe and then creating a file to send to SAP but we are concerned about overlaying files. We did something similar in 2 UNIX environments using the startrfc command but mainframe files are a little different due to the naming conventions. Also not sure about the startrfc because of the frequency that data will be entered on the mainframe side.

Looking for the best solution with the tools that we already have inplace due to time constraints.

Thanks in advance!