In a BPEL process, every piece of data is in XML forms. This includes the messages passed to and from the BPEL process, the messages exchanged with EXTERNAL services, and local variables USED by the process. You define the types for these messages and variables with the XML SCHEMA, USUALLY in the WSDL file for the flow, the WSDL files for the services it invokes, or the XSD file referenced by those WSDL files. Therefore, all variables in BPEL are XML data, and any BPEL process uses much of its code to manipulate these XML variables. This typically includes performing data transformation between representations required for different services, and local manipulation of data (for example, to combine the results from several service invocations).

In a BPEL process, every piece of data is in XML forms. This includes the messages passed to and from the BPEL process, the messages exchanged with external services, and local variables used by the process. You define the types for these messages and variables with the XML schema, usually in the WSDL file for the flow, the WSDL files for the services it invokes, or the XSD file referenced by those WSDL files. Therefore, all variables in BPEL are XML data, and any BPEL process uses much of its code to manipulate these XML variables. This typically includes performing data transformation between representations required for different services, and local manipulation of data (for example, to combine the results from several service invocations).