Open Metadata OutTopic¶
The Open Metadata OutTopic is an event topic used to send metadata change notifications out from a metadata access server to the services that need to react to them - typically the governance servers and view servers, but also any external technology that has been connected to the topic.
The OutTopic is what makes the open metadata ecosystem event-driven rather than poll-driven. Instead of a governance service repeatedly asking whether anything has changed, it subscribes to the OutTopic and is told. A watchdog action service monitoring for a situation, an integration connector keeping a third party catalog in step, or a listener maintaining a search index all work this way.
Each Open Metadata Access Service (OMAS) has its own OutTopic, and publishes the events that are relevant to its own area of interest. A consumer therefore subscribes to the topic of the service whose subject matter it cares about, rather than filtering the whole stream.
The topic itself is accessed through an open metadata topic connector, which is nested inside the runtime connector for whichever event bus technology the deployment uses - Apache Kafka, for example. This means the event format is independent of the messaging technology carrying it.
Additional information
- Open metadata topic connector describes how events are read from and written to the topic.
- Notification type describes how the situations detected from these events are defined, and who is told about them.
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