Publishers and Subscribers may be configurable through vendor-specific engineering tools or with the configuration Methods and parameters described in this document. This allows a standard OPC UA Client based configuration tool to configure an OPC UA Server that is a Publisher and/or Subscriber.
The latest configuration shall be persisted by the OPC UA Server and shall be available after a restart of the OPC UA Server. PubSub components are not persisted, if the component has the optional NotPersisted property set with a value of true. The PubSub configuration properties are defined in 6.2.2.
Configuration parameters are exposed as Variables of the configurable Objects. Methods for creation of Objects have input arguments for mandatory Variables. Optional Variables are created with a default value if they are supported for the Object or required for the current configuration. The default value can be changed by writing to the Variable after creation. The Status newly created Objects depend on the enabled flag in the configuration Structures if they are created with the standard Methods.
Variables that can be configured shall have the CurrentWrite flag set in the AccessLevel Attribute. The UserAccessLevel may be limited based on the rights of the user of the OPC UA Client.
Configuration changes shall be applied in a batch to avoid inconsistencies between different configuration parameters. The mechanism to apply changes in a batch operation is to allow changes through parameter write only when the related Object has the Status Disabled and to apply the new configuration settings when the Status is changed to Operational. Therefore write operations to configuration parameters shall be rejected with Bad_InvalidState if the Status is not Disabled.
Configuration changes based on Method calls can be applied in Status Operational since the Methods provide batch operations. If configuration changes require different Method calls, it is recommended to disable the affected Objects to apply the changes in a batch.
Add, modify and remove operations for all PubSub configuration elements including DataSets and security key exchange configuration can be executed in one atomic write operation through the PubSubConfiguration Object. It allows also read access to the complete PubSub configuration. Both read and write access are handled through FileType functionality. The related functionality is defined in 18.104.22.168.
Modifications of the PubSub configuration can happen through different mechanisms like FileType access or sequences of Method calls. The PubSub application should ensure that all mechanisms coordinate access to the configuration. The coordination should not immediately fail parallel access. It should delay access in the range of timeout settings for Method calls.