Generating SAP ABAP code/ script from XML coming from an external application

Yes, this is feasible. You can create simple transformation for XML in ABAP. You can also use cl_proxy_xml_transform to transform data between XML and ABAP. Let us say that you have created ABAP proxy using T-Code: SPROXY or it is generated via WebService generation utility, you can use utility class “cl_proxy_xml_transform” to convert data of the ABAP to XML format or also from XML → ABAP.