Client/server system for communicating according to the standard protocol opc ua and having single sign-on mechanisms for authenticating, and method for performing single sign-on in such a system

A method for integrating single sign-on (SOS) mechanisms in a client/server system with communication according to the OPC UA protocol and for performing SOS for user authentication in the system, wherein the system includes an OPC UA client which is connected to an OPC UA aggregating server, which in turn is connected to subordinate OPC UA servers by means of a communication network, the method comprising:

• providing, in order to integrate SOS mechanisms, the OPC UA aggregating server with an SSO component for mapping user legitimation data, which are used in a service call, to identities in a form in which the identities are stored in the subordinate OPC UA servers;
• and
• utilizing, in order to perform SOS with the aid of the SOS component, user legitimation data belonging to a service call to automatically look for corresponding mapped identities and for affected OPC UA servers and, for each match, to call an ActivateSession service in the respective OPC UA server using the mapped identity, after which the data access desired with the user's service call is established.