OPC UA defines a standard approach for implementing role-based security. Servers may choose to implement part or all of the mechanisms defined here. The OPC UA approach assigns Permissions to Roles for each Node in the AddressSpace. Clients are then granted Roles when they create a Session based on the information provided by the Client.
Roles are used to separate authentication (determining who a Client is with a user token and Client application identity) from authorization (Permissions determining what the Client is allowed to do). By separating these tasks Servers can allow centralized services to manage user identities and credentials while the Server only manages the Permissions on its Nodes assigned to Roles.
OPC 10000-3 defines the possible Permissions and the representation as Node Attributes.
Figure 1 depicts the ObjectTypes, Objects and their components used to represent the Role management.
