1. A data processing method comprising: using a processor to perform: receiving a SOAP message that is described in an XML format and includes a data part, a specification part indicating specifications of a service to process the data part, and a program part, wherein the specification part is described in the XML format and is used for describing a Web service; performing instructions comprised in the program part which is described in the XML format using Business Process Execution Language for Web Services (BPEL4WS); and performing a specific process on data included in the data part, wherein the specific process is performed by the service, specifications of the service being indicated in the specification part, when an instruction including a reference to the service is included in the instructions comprised in the program part of the received message.