The first OPC Unified Architecture Book, written by Wolfgang Mahnke, Stefan-Helmut Leitner and Matthias Damm one of the co-founders of ascolab.

OPC UA Base Services

Abstract Definition of Services

The service oriented architecture (SOA) follows the request/response paradigm. OPC UA defines a fixed set of services with exactly defined parameters and behavior. These services are generic, there is for instance only one “Read” service for reading attributes, i.e. data as well as properties. In contrast to classic OPC, there is only one “Browse” service, instead of DA browse, AE browse, and HDA browse, for browsing a UA server’s address space whereby the client decides which references (between nodes) to follow. This unification of services and features is one of the essential innovations of OPC UA. Its genericity and standardization guarantee interoperability. The base services are according to the functions divided into so-called “service sets”

The following list shows these groups of services.

Service Set Description
SecureChannel Service Set retrieve endpoint and security configuration to establish a secure connection
Session Service Set create and administrate user-specific connection between application
NodeManagement Service Set modify the server’s address space (if permitted)
View Service Set navigate and follow (hierarchical) references in the server’s address space, search for and filter information
Attribute Service Set read and write attributes of (an) node(s), especially the value attribute, but historical data or events as well
Method Service Set invoke methods which a server provides at the nodes in its address space
MonitoredItem Service Set create a set of attributes of nodes to be monitored by the server and for which changes should be reported
Subscription Service Set create, modify, or delete monitored items
Query Service Set perform a filtered search for information in the server’s address space