Method and apparatus for expanding transactions in OPC UA

A client device adapted for communication with a server in a client/server system using the OPC UA (Open Platform Communication Unified Architecture) communication protocol, said client device transmitting service calls and special service calls to the server, said client device comprising:

• a client, said client adapted to open a communication session with a server using an OPC UA special service call;
• and
• a simulation processor, said simulation processor adapted for receiving and storing at least a first OPC UA service call transmitted by the client to the server during said communication session, and for initially only simulating execution of the stored first OPC UA service call during said communication session, without the server actually executing the first OPC UA service call, the simulation processor further adapted for receiving and storing at least one second OPC UA service call from the client in said communication session, with the simulation processor using the result of the Initial simulation of the first OPC UA service call to initially simulate the execution of the at least one second OPC UA service call in said communication session and providing the result of the initial simulation of the stored first and the at least one second OPC UA service call to the client in response to the stored at least one second OPC UA service call, wherein the server actually executes the first and the at least one second simulated OPC UA service call only when receiving from the client an OPC UA special service call for closing the communication session.

A server device adapted for communication with a client in a client/server system using the OPC UA (Open Platform Communication Unified Architecture) communication protocol, said server device comprising:

• a server adapted for receiving service calls and special service calls from the client, said server being adapted to open a communication session in response to a special service call from the client;
• and
• a simulation processor adapted for receiving and storing a first and at least one second OPC UA service call received from the client by the server in said communication session, and further adapted for initially only simulating execution of the stored first OPC UA service call during said communication session, without the server actually executing the first OPC UA service call, and for using a result of the initial simulation of said first OPC UA service call to initially simulate the execution of the at least one second OPC UA service call in said communication session,
• wherein the result of the initial simulation of the first and the at least one second stored OPC UA service call is provided to the client as a response to the stored at least one second OPC UA service call, and wherein the server actually executes the first and the at least one second simulated OPC UA service call only when receiving from the client an OPC UA special service call for closing the communication session.