6. The method according claim 5 characterized in that for mapping an XML web service to an ontology the following steps are performed: providing an XML SOAP (Simple Object Access Protocol) web service with a corresponding web service description (WSDL); a) mapping the WSDL definitions to ontology schema definitions in the following way: mapping an operation definition to a class definition of the ontology; mapping a part definition to an ontology property definition; b) the input and output message of the SOAP request are mapped in the following way to ontology instances: a single SOAP request is mapped to a single ontology class instance; the element nodes representing the parts of the input and output message are mapped to ontology property instances.
7. The method according to claim 6 comprising the steps of: a) mapping the WSDL definitions to ontology schema definitions in the following way: a1) mapping an operation definition to a class definition of the ontology; a2) if the part of the input or output message is defined as an complexContent element declaration, it is mapped to an object property definition of the ontology, the object property having a domain class and a range class, the domain class being the class which is mapped from the operation definition, and the range class of the object property being the class to which the complexType of the complexContent element is mapped; a3) if the part of the input or output message is defined as an XSD simpleType element declaration without attributes, it is mapped to a datatype property definition of the ontology, the datatype property having a domain class, which is mapped from the operation definition and the range type being the XML schema type of the simpleType element declaration; a4) if the part of the input or output message is defined as an XSD simpleContent element declaration with an attribute, it is mapped to an object property definition of the ontology, the object property having a domain class and a range class, the domain class being the class, which is mapped from the operation definition, and the range class of the object property being the class to which the complexType of the simpleContent element is mapped.