There is a standard ABAP function module within SAP that provides the ability to upload a file from the desktop / client to the ABAP. The ABAP program that you wrap around this function module call has to determine what to do with the data (i.e. process it as data, save it to the server, etc). With a bit of work, on a WEB AS release of the ABAP engine, this can be incorporated in a Web Dynpro or BSP page to perform the load from a web page.
There is functionality within the JAVA stack (Portals etc) that allows you to upload text and binary data to such components of SAP as Knowledge Managemnt..