PubSubdefines different configuration parameters for the various PubSubcomponents. They define the behaviour of Publisherand Subscriber. The parameters are grouped by component and are partitioned into ‘common’, ’message mapping’, and ‘transport protocol mapping’.
The application of communication parameters for concrete message and transport protocol mappings is defined in clause 7.
Configuration of these parameters can be performed through the OPC UA Information Modelfor PubSubconfiguration defined in clause 9or through vendor-specific mechanisms. The parameter groupings in this clause define the parameters and also define Structuresused to represent the parameters of the groupings. These Structuresare used in the PubSubconfiguration model described in clause 9but they can also be used for offline configuration or vendor-specific configuration mechanisms.
Figure 17depicts the different components and their relation to each other. The WriterGroup, DataSetWriterand PublishedDataSetcomponents define the data acquisition for the DataSets, the message generation and the sending on the Publisherside. These parameters need to be known on the Subscriberside to configure DataSetReadersand to filter and process DataSetMessages.
The figure shows the following components:
- PublishedDataSetcontains the DataSetMetaDatadescribing the content of the DataSetsproduced by the PublishedDataSetand the corresponding data acquisition parameters.
- DataSetWriterparameters are necessary for creating DataSetMessages. Each DataSetWriteris bound to a single PublishedDataSet. A PublishedDataSetcan have multiple DataSetWriters.
- WriterGroupparameters are necessary for creating a NetworkMessage. Each writer group can have one or more DataSetWriters. Some of these parameters are used for creating the DataSetMessages. They are grouped here since they are the same for all DataSetMessagesin a single NetworkMessage.
- PubSubConnectionparameters represent settings needed for the transport protocol. One connection can have a number of writer groups and reader groups.
- ReaderGroupis used to group a list of DataSetReadersand contains a few shared settings for them. It is not symmetric to a WriterGroupand it is not related to a particular NetworkMessage. The NetworkMessagerelated filter settings are on the DataSetReaders.
- DataSetReaderparameters represent settings for filtering of received NetworkMessagesandDataSetMessagesas well as settings for decoding of the DataSetMessagesof interest.
- SubscribedDataSetparameters define the processing of the decoded DataSetin the Subscriberfor one DataSetReader.
- PublishSubscribeis the overall management of the PubSubgroupings. It contains a list of PublishedDataSetsand a list of PubSubConnections.
The different PubSub mapping specific parameter groupings are shown in Figure 18.