4 Structure of the OPC UA series

4.1 Specification organization

This specification is organized as a multi-part specification, as illustrated in Figure 1.

The first seven parts specify the core capabilities of OPC UA. These core capabilities define the structure of the OPC AddressSpace and the Services that operate on it. Parts 8 through 11 apply these core capabilities to specific types of access previously addressed by separate OPC COM specifications, such as Data Access (DA), Alarms and Events (A&E) and Historical Data Access (HDA). Part 12 describes Discovery mechanisms for OPC UA and Part 13 describes ways of aggregating data. Readers are encouraged to read Parts 1 through 5 of the core specifications before reading Parts 8 through 13. For example, a reader interested in UA Data Access should read Parts 1 through 5 and 8. References in Part 8 may direct the reader to other parts of this specification.

4.2 Core specification parts

Part 1 – Overview and Concepts Part 1 (this part) presents the concepts and overview of OPC UA.

Part 2 – Security Model Part 2 describes the model for securing interactions between OPC UA Clients and OPC UA Servers.

Part 3 – Address Space Model Part 3 describes the contents and structure of the Server’s AddressSpace.

Part 4 – Services Part 4 specifies the Services provided by OPC UA Servers.

Part 5 – Information Model Part 5 specifies the types and their relationships defined for OPC UA Servers.

Part 6 – Mappings Part 6 specifies the mappings to transport protocols and data encodings supported by OPC UA.

Part 7 – Profiles Part 7 specifies the Profiles that are available for OPC Clients and Servers. These Profiles provide groups of Services or functionality that can be used for conformance level certification. Servers and Clients will be tested against the Profiles.

4.3 Access Type specification parts

Part 8 – Data Access Part 8 specifies the use of OPC UA for data access.

Part 9 – Alarms and Conditions Part 9 specifies use of OPC UA support for access to Alarms and Conditions. The base system includes support for simple Events; this specification extends that support to include support for Alarms and Conditions.

Part 10 – Programs Part 10 specifies OPC UA support for access to Programs.

Part 11 – Historical Access Part 11 specifies use of OPC UA for historical access. This access includes both historical data and historical Events.

4.4 Utility specification parts

Part 12 – Discovery Part 12 specifies how Discovery Servers operate in different scenarios and describes how UA Clients and Servers should interact with them. It also defines how UA related information should be accessed using common directory service protocols such as UDDI and LDAP.

Part 13 – Aggregates Part 13 specifies how to compute and return aggregates like minimum, maximum, average etc. Aggregates can be used with current and historical data. .