Method for communication between two OPC-UA clients (5, 14) via an OPC-UA server in a network using OPC-UA, - a virtual server object being implemented in the OPC-UA server, which virtual server object provides a first of the two OPC-UA clients (5, 14) with a functionality of an OPC-UA server by providing the first OPC-UA client with a virtual address space in an address space of the OPC-UA server and a method for generating and changing virtual server nodes in the virtual address space, - the OPC-UA server making it possible for the second OPC-UA client to access virtual server nodes in the virtual address space, and - the OPC-UA server informing the first OPC-UA client each time the second OPC-UA client accesses a virtual server node in the virtual address space, wherein the OPC-UA server generates a subscription for the first client, and the subscription contains a subscription entity, in response to the change in which the first OPC-UA client is registered and which is changed by the OPC-UA server when the second OPC-UA client accesses a virtual server node in the virtual address space, characterized in that - the second client transmits a read request to the server in order to request the value of the virtual server node, - the server changes the value of the subscription entity in the form of a subscription variable and notifies the first client by means of a value change message, - the first client transmits a write request to the server, said write request containing a value of the virtual server node and a call of a method of the virtual server object for writing this value, - the server object updates the value of the virtual server node, and - the server transmits a value notification to the second client, said value notification notifying the second client of the current value of the virtual server node. - a virtual server object being implemented in the OPC-UA server, which virtual server object provides a first of the two OPC-UA clients (5, 14) with a functionality of an OPC-UA server by providing the first OPC-UA client with a virtual address space in an address space of the OPC-UA server and a method for generating and changing virtual server nodes in the virtual address space, - the OPC-UA server making it possible for the second OPC-UA client to access virtual server nodes in the virtual address space, and - the OPC-UA server informing the first OPC-UA client each time the second OPC-UA client accesses a virtual server node in the virtual address space, - the second client transmits a read request to the server in order to request the value of the virtual server node, - the server changes the value of the subscription entity in the form of a subscription variable and notifies the first client by means of a value change message, - the first client transmits a write request to the server, said write request containing a value of the virtual server node and a call of a method of the virtual server object for writing this value, - the server object updates the value of the virtual server node, and - the server transmits a value notification to the second client, said value notification notifying the second client of the current value of the virtual server node.