Calling BAPI/RFC enabled function via XML in WAS

Hi

We have a scenario where a external procurement system should call BAPIs inside WAS 6.20 zu created e.g. purchase orders. I think in the past this has been regarded as a typical scenario for SAP business connector. But why install SAP BC if we have WAS 6.20? Is there service inside WAS that "understands" RFC-XML like the SAP BC? Is it recommended to use web services (see OSS note 566955 SOAP processor for ABAP). Which way is the recommended, stable solution???

thanks

Michael