For example, Librados EICA Framework includes a JCA adapter for SAP which provides an XML Schema describing the data types that flow in and out of the JCA adapter. In other words, the native SAP (RFC) types, are projected into an XML Schema document. This makes it easy for the BPEL server to generate a WSDL as a wrapper with a specific binding element.
When a BPEL process executes an <invoke> activity, the BPEL server uses a WSIF framework to call the specified partnerLink and consequently dispatch the JCA WSIF Provider (which wraps the JCA adapter). The XML message from the BPEL process is then translated by the JCA adapter into the native data types and a JCA call is made to SAP. The response from SAP is then translated back from native data types to an XML message by the adapter and returned to the BPEL process.