OPC UA Services

Services are methods used by an OPC UA Client to access the data of the information model provided by an OPC UA Server. The services define the communication interface between UA applications. The OPC UA service definition is of course abstract and the API’s  are defined by the OPC UA stacks based on the abstract UA Service definition from the OPC Foundation.

Below is a diagram of the UA communication layering.

The Web Service is an XLM based protocol, where as the UC TCP binding is a light weight binary protocol, made for performance

To know more, read chapter 5 of the book OPC Unified Architecture.