SAP integration with non sap System

Hello Experts

i need your advice on below issue:

I have requirement to get Information from non-sap System(probably DB Database) and than do some posting in SAP System.

To explain above issue more clearly, for ex: look for material in non-sap System , if exists than will take all the required fields (back to sap System) and do posting in sap System(Materail creation).

Restriction: NO work or custom development at non-sap System.

what options are available to me: i would like to use something like ABAP Connection, where i don't need to install any connector at receiving side, but due to non sap System - i cannot use the same.

Kindly let me know, if you have any info.