Functional Principle
Web services are applications using open and XML-based standards and transport protocols for exchanging data with clients.
Providing and requesting Web Services
Service providers provide descriptions of their Web Services as WSDL file. The WSDL file describes the operations, data and exchange protocols the Web Service offers. This information is machine-readable.
Based on this WSDL file service consumers create a SOAP request in order to access one of the Web Service’s operations.
The Web Service processes the SOAP request and returns the result as SOAP response to the service consumer.