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Extended Properties

Extended properties provide a means to maintain the properties of elements that are subtypes of the types supported directly on an API.

For example, the Data Manager OMAS has support for maintaining metadata about Topics. Topics are special types of assets that provide a destination for exchanging events.

Model 0223 Events and Logs extends the Topic type with a new type called KafkaTopic that introduces two new properties: partitions and replicas. KafkaTopic is used to represent a topic that is owned and managed by Apache Kafka. The full type hierarchy for KafkaTopic is shown in Figure 1.

Figure 1 Figure 1: The type inheritance hierarchy for KafkaTopic. This shows all of the properties that are valid for an element of type KafkaTopic. Properties qualifiedName and additionalProperties are inherited from Referenceable; properties name and description are inherited from Asset; finally topicType is inherited from Topic. All of these properties are supported natively by the Data Manager OMAS. The partitions and replicas properties introduced by the KafkaTopic type are maintainable through extendedProperties.

The code snippet below shows a call to the Data Manager OMAS to create an element of type KafkaTopic. The standard properties for a topic are set up first. Then the name of the subtype for the new element (null means Topic). Then any extended properties for the requested subtype are set up. Finally any additional properties that the organization wants to store that are not defined in the type definitions go in additionalProperties.

   TopicProperties topicProperties = new TopicProperties();

    * Set up the standard properties - note displayName maps to the name property.
   topicProperties.setDescription("Testing that topics can be catalogued");

    * Set up the specific type name for the new element. It must be a null
    * (for a type of Topic) or a type name that is a subtype of Topic.

    * Set up the properties that come from the subtypes of Topic.
   Map<String, Object> extendedProperties = new HashMap<>();
   extendedProperties.put("partitions", 1);
   extendedProperties.put("replicas", 5)

    * Set up additional properties.  These do not need to be defined in any of the
    * type definitions.
   Map<String, String> additionalProperties = new HashMap<>();
   additionalProperties.put("autoDefined", "true");
   additionalProperties.put("jsonPayload", "true");

   String topicGUID = dataManagerClient.createTopic(userId,