Data processing systems and methods are disclosed for providing a payment using a Web service. In one implementation, a first computer is used for entry of data values into respective data entry fields of an electronic data entry form. Further, an identifier of the Web service, such as the uniform resource locator (URL) of the Web service, is entered into the first computer. Next, the first computer initiates data processing for providing the payment that is to be performed by a second computer on the basis of the data values entered into the electronic data entry form. The initiation and/or performance or completion of the data processing is signaled to the Web service by sending corresponding signaling data, which includes payment advice data of the payment. The Web service is coupled to a third computer that receives a result of the data processing from the second computer.