Research And Development For The OPC UA Server's Subscription And Monitored Item Services Based On Binary Communication

The traditional OPC that based on the COM/DCOM access the data is the OPC client periodic visit OPC server, this way directly influence on the work efficiency between the client and server. Although OPC UA solving the problem that is not cross-platform-ability, not able to carry on interoperability and so on, it still access server using the polling way. In order to improve the working efficiency of the OPC UA server, callback mechanism is used to realize the OPC UA server subscription services. The client could not inquires the server periodic whether has a notification message or not by the callback mechanism, however, the server send notification message to the client by calling the services in the client when the server needs to send notification message. The callback of OPC UA server could be realize by WCF technology. Because the OPC UA server is developed on SOA. WCF technology is the communication interface for SOA program and the callback is also Communication methods, so we could use the callback mechanism of WCF in the OPC UA server to realize its subscription service, and improve the efficiency of the communication.