An instance of the PublishSubscribeTypewith the name PublishSubscriberepresents the root Objectfor all PubSubrelated Objects. It manages a list of PubSubConnectionType Objectsand the PublishedDataSetType Objectsthrough the PublishedDataSetsfolder.
On the Publisherside, a PublishedDataSetrepresents the information to publish and the DataSetWriterrepresents the transport settings for creating DataSetMessagesfor delivery through a Message Oriented Middleware.
On the Subscriberside, a DataSetReaderrepresents the transport settings for receiving DataSetMessagesfrom a Message Oriented Middlewareand the SubscribedDataSetrepresents the information to dispatch the received DataSetsin the Subscriber.
Figure 37depicts the information flow and the related ObjectTypesfrom the PubSub Information Model. The boxes in the lower part of the figure are examples for blocks necessary to implement the information flow in a Publisher.
The PublishedDataSetType represents the selection and configuration of Variablesor Events. An Eventnotification or a snapshot of the Variablescomprises a DataSet. A DataSetis the content of a DataSetMessagecreated by a DataSetWriter. Examples of concrete PublishedDataSetTypes are PublishedEventsTypeand PublishedDataItemsType. An instance of PublishedDataSetType has a list of DataSetWriters used to produce DataSetMessagessent via the Message Oriented Middleware. The DataSetMetaDatadescribes the content of a DataSet.
Instances of the PubSubConnectionTyperepresent settings associated with Message Oriented Middleware. A connection manages a list of WriterGroupType Objectsand transport protocol mapping specific parameters.
Instances of the WriterGroupTypecontain instances of DataSetWriter Objectsthat share settings such as security configuration, encoding or timing of NetworkMessages. A group manages a list of DataSetWriterTypeObjects that define the payload of the NetworkMessagescreated from the group settings.
NetworkMessagesare sent through a transport like AMQP, MQTT or OPC UA UDP. Other transport protocols can be added as subtypes without changing the base model.
The definition of the PubSubrelated ObjectTypesdoes not prescribe how the instances are created or configured or how dynamic the configuration can be. A Publishermay have a preconfigured number of PublishedDataSetsand DataSetWriterswhere only protocol specific settings can be configured. If a Publisherallows dynamic creation of Objectslike DataSetsand DataSetWriters, this can be done through product specific configuration tools or through the standardized configuration Methodsdefined in this specification.