Publishersand Subscribersmay be configurable through vendor-specific engineering tools or with the configuration Methodsand parameters described in this document. This allows a standard OPC UA Client based configuration tool to configure an OPC UA Serverthat is a Publisherand/or Subscriber.
The latest configuration shall be persisted by the OPC UA Serverand shall be available after a restart of the OPC UA Server. PubSubcomponents are not persisted, if the component has the optional NotPersistedproperty set with a value of true. The PubSubconfiguration properties are defined in 6.2.2.
Configuration parameters are exposed as Variablesof the configurable Objects. Methodsfor creation of Objectshave input arguments for mandatoryVariables. Optional Variablesare created with a default value if they are supported for the Objector required for the current configuration. The default value can be changed by writing to the Variableafter creation. The Status newly created Objectsdepend on the enabled flag in the configuration Structuresif they are created with the standard Methods.
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 Objecthas the Status Disabledand to apply the new configuration settings when the Statusis changed toOperational. Therefore write operations to configuration parameters shall be rejected with Bad_InvalidStateif the Statusis notDisabled.
Configuration changes based on Methodcalls can be applied in Status Operationalsince the Methodsprovide batch operations. If configuration changes require different Methodcalls, it is recommended to disable the affected Objectsto apply the changes in a batch.
Add, modify and remove operations for all PubSub configuration elements including DataSetsand 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 FileTypefunctionality. The related functionality is defined in 18.104.22.168.
Modifications of the PubSubconfiguration can happen through different mechanisms like FileTypeaccess or sequences of Methodcalls. The PubSubapplication 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 Methodcalls.