0223 Events and Logs¶
Processing is often triggered when a specific event or situation occurs. There are also sources of data that provide a continuous feed of data - for example a sensor monitoring the temperature. This model introduces the different types of Assets associated with events and continuous data feeds.
DataFeed identifies an asset that provides a continuous feed of data.
A Topic is a type of DataSet that is accessed using a publish-subscribe event interface. There are processes that add events to the topic, and other processes that subscribe to the topic and receive a copy of each event that is added. It is shown as a data set because some topics are in memory and some make use of an underlying DataStore to provide a persistent/reliable delivery service.
Apache Kafka is a popular open source technology that provides support for Topics. There is a specific type for an Apache Kafka topic because there is a resource connector for Apache Kafka and this type identifies when it is appropriate to use this connector to access the topic contents.
SubscriberList and TopicSubscribers¶
Some services manage a specific subscriber list. This is represented by the SubscriberList entity type. The links to the topics that the subscription refers to is represented by the TopicSubscribers relationship type.
A LogFile entity is a subtype of DataFile that contains events that have been captured and stored.
The AssociatedLog relationship shows the Asset (typically a LogFile) where logging information for the linked Referenceable is located.
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