Topic properties

When you create topics, you assign properties to them. The properties a topic can have depends on the topic type.
The following table shows properties available for each topic type.

Topic properties for topic types
Type	JSON	Binary	String	Int64	Double	Time Series	RecordV2
Publish values only
Don’t retain values
Tidy on Unsubscribe
Time series event value type
Time series retained range
Time series subscription range
Validate values
Schema
Conflation
Compression
Owner
Removal
Persistent
Priority

Examples

To set the above properties in each of the SDKs, refer to the following examples:

Java and Android

final Map<String, String> properties = new HashMap<>();
properties.put(DONT_RETAIN_VALUE, "true");
properties.put(PUBLISH_VALUES_ONLY, "true");
properties.put(TIDY_ON_UNSUBSCRIBE, "true");
properties.put(PERSISTENT, "false");

session.feature(TopicControl.class).addTopic("my/topic/path",
    newTopicSpecification(TopicType.JSON).withProperties(properties));

JavaScript

const topic_properties = {
    'DONT_RETAIN_VALUE': 'true',
    'PUBLISH_VALUES_ONLY': 'true',
    'TIDY_ON_UNSUBSCRIBE': 'true',
    'PERSISTENT': 'false'
};
const specification = new diffusion.TopicSpecification(diffusion.topics.TopicType.JSON, topic_properties);

const result = await session.topics.add('my/topic/path', specification);

if (result.added) {
    console.log(`Topic "${result.topic}" has been successfully created`);
} else {
    console.log('Topic already exists.')
}

.NET

var topicProperties = new Dictionary<string, string> {
        { TopicSpecificationProperty.DontRetainValue, "true" },
        { TopicSpecificationProperty.PublishValuesOnly, "true" },
        { TopicSpecificationProperty.TidyOnUnsubscribe, "true" },
        { TopicSpecificationProperty.Persistent, "false" }
    };

var specification = Diffusion.NewSpecification(TopicType.JSON).WithProperties(topicProperties);

var result = await session.TopicControl.AddTopicAsync("my/topic/path", specification);

if (result == AddTopicResult.EXISTS)
{
    WriteLine($"Topic already exists.");
}
else
{
    WriteLine($"Topic has been successfully created.");
}

static int on_topic_added_with_properties(
        SESSION_T *session,
        TOPIC_ADD_RESULT_CODE result_code,
        void *context)
{
        return HANDLER_SUCCESS;
}


...


HASH_T *properties = hash_new(1);
hash_add(properties, DIFFUSION_DONT_RETAIN_VALUE, strdup("true"));
hash_add(properties, DIFFUSION_PUBLISH_VALUES_ONLY, strdup("true"));
hash_add(properties, DIFFUSION_TIDY_ON_UNSUBSCRIBE, strdup("true"));
hash_add(properties, DIFFUSION_PERSISTENT, strdup("false"));

TOPIC_SPECIFICATION_T *specification =
        topic_specification_init_with_properties(TOPIC_TYPE_JSON, properties);

ADD_TOPIC_CALLBACK_T callback = {
        .on_topic_added_with_specification = on_topic_added_with_properties
};

add_topic_from_specification(session, "my/topic/path", specification, callback);

Python

from diffusion.features.topics.details.topic_specification import TopicSpecification

specification = TopicSpecification.new_topic_specification(diffusion.datatypes.JSON) \
                                  .with_properties(DONT_RETAIN_VALUE=True,
                                                   PUBLISH_VALUES_ONLY=True,
                                                   TIDY_ON_UNSUBSCRIBE=True,
                                                   PERSISTENT=False)
await session.topics.add_topic("my/topic/path", specification)
print("Topic has been added!")

Apple

let topic_properties = [
    PTDiffusionTopicSpecification.dontRetainValuePropertyKey(): "true",
    PTDiffusionTopicSpecification.publishValuesOnlyPropertyKey(): "true",
    PTDiffusionTopicSpecification.tidyOnSubscribePropertyKey(): "true",
    PTDiffusionTopicSpecification.persistentPropertyKey(): "false"
]
let specification = PTDiffusionTopicSpecification.init(
    type: PTDiffusionTopicType.JSON,
    properties: topic_properties
)
session.topicControl.addTopic(
    withPath: "my/topic/path",
    specification: specification) { (result, error) in
        if (result == PTDiffusionAddTopicResult.exists()) {
            print("Topic already exists.")
        }
        else {
            print("Topic has been successfully created.")
        }
}