# Topic

## Topic

This schema defines the Topic entity. A topic is a feed into which message are published to by publishers and read from by consumers in a messaging service.

**$id:**[**https://open-metadata.org/schema/entity/data/topic.json**](https://open-metadata.org/schema/entity/data/topic.json)

Type: `object`

This schema does not accept additional properties.

### Properties


* **id** `required`
  * Unique identifier that identifies this topic instance.
  * $ref: [../../type/basic.json#/definitions/uuid](../types/basic.md#uuid)
* **name** `required`
  * Name that identifies the topic.
  * $ref: [#/definitions/topicName](topic.md#topicname)
* **fullyQualifiedName**
  * Name that uniquely identifies a topic in the format 'messagingServiceName.topicName'.
  * Type: `string`
* **displayName**
  * Display Name that identifies this topic. It could be title or label from the source services.
  * Type: `string`
* **description**
  * Description of the topic instance.
  * Type: `string`
* **version**
  * Metadata version of the entity.
  * $ref: [../../type/entityHistory.json#/definitions/entityVersion](../types/entityhistory.md#entityversion)
* **updatedAt**
  * Last update time corresponding to the new version of the entity in Unix epoch time milliseconds.
  * $ref: [../../type/basic.json#/definitions/timestamp](../types/basic.md#timestamp)
* **updatedBy**
  * User who made the update.
  * Type: `string`
* **service** `required`
  * Link to the messaging cluster/service where this topic is hosted in.
  * $ref: [../../type/entityReference.json](../types/entityreference.md)
* **serviceType**
  * Service type where this topic is hosted in.
  * $ref: [../services/messagingService.json#/definitions/messagingServiceType](messagingservice.md#messagingservicetype)
* **schemaText**
  * Schema used for message serialization. Optional as some topics may not have associated schemas.
  * Type: `string`
* **schemaType**
  * Schema used for message serialization.
  * $ref: [#/definitions/schemaType](topic.md#schematype)
* **partitions** `required`
  * Number of partitions into which the topic is divided.
  * Type: `integer`
  * Range: ≥ 1
* **cleanupPolicies**
  * Topic clean up policies. For Kafka - `cleanup.policy` configuration.
  * Type: `array`
    * **Items**
    * $ref: [#/definitions/cleanupPolicy](topic.md#cleanuppolicy)
* **retentionTime**
  * Retention time in milliseconds. For Kafka - `retention.ms` configuration.
  * Type: `integer`
* **replicationFactor**
  * Replication Factor in integer (more than 1).
  * Type: `integer`
* **maximumMessageSize**
  * Maximum message size in bytes. For Kafka - `max.message.bytes` configuration.
  * Type: `integer`
* **minimumInSyncReplicas**
  * Minimum number replicas in sync to control durability. For Kafka - `min.insync.replicas` configuration.
  * Type: `integer`
* **retentionSize**
  * Maximum size of a partition in bytes before old data is discarded. For Kafka - `retention.bytes` configuration.
  * Type: `integer`
  * Default: _"-1"_
* **topicConfig**
  * Contains key/value pair of topic configuration.
  * $ref: [#/definitions/topicConfig](topic.md#topicconfig)
* **owner**
  * Owner of this topic.
  * $ref: [../../type/entityReference.json](../types/entityreference.md)
* **followers**
  * Followers of this table.
  * $ref: [../../type/entityReference.json#/definitions/entityReferenceList](../types/entityreference.md#entityreferencelist)
* **tags**
  * Tags for this table.
  * Type: `array`
    * **Items**
    * $ref: [../../type/tagLabel.json](../types/taglabel.md)
* **href**
  * Link to the resource corresponding to this entity.
  * $ref: [../../type/basic.json#/definitions/href](../types/basic.md#href)
* **changeDescription**
  * Change that lead to this version of the entity.
  * $ref: [../../type/entityHistory.json#/definitions/changeDescription](../types/entityhistory.md#changedescription)
* **deleted**
  * When `true` indicates the entity has been soft deleted.
  * Type: `boolean`
  * Default: _false_

> > > > > > > a07bc411 (updated json schema and schema docs (#3219))

* **id** `required`
  * Unique identifier that identifies this topic instance.
  * $ref: [../../type/basic.json#/definitions/uuid](../types/basic.md#uuid)
* **name** `required`
  * Name that identifies the topic.
  * $ref: [#/definitions/topicName](topic.md#topicname)
* **fullyQualifiedName**
  * Name that uniquely identifies a topic in the format 'messagingServiceName.topicName'.
  * Type: `string`
* **displayName**
  * Display Name that identifies this topic. It could be title or label from the source services.
  * Type: `string`
* **description**
  * Description of the topic instance.
  * Type: `string`
* **version**
  * Metadata version of the entity.
  * $ref: [../../type/entityHistory.json#/definitions/entityVersion](../types/entityhistory.md#entityversion)
* **updatedAt**
  * Last update time corresponding to the new version of the entity in Unix epoch time milliseconds.
  * $ref: [../../type/basic.json#/definitions/timestamp](../types/basic.md#timestamp)
* **updatedBy**
  * User who made the update.
  * Type: `string`
* **service** `required`
  * Link to the messaging cluster/service where this topic is hosted in.
  * $ref: [../../type/entityReference.json](../types/entityreference.md)
* **serviceType**
  * Service type where this topic is hosted in.
  * $ref: [../services/messagingService.json#/definitions/messagingServiceType](https://github.com/open-metadata/OpenMetadata/blob/main/docs/openmetadata-apis/schemas/services/messagingservice.md#messagingservicetype)
* **partitions** `required`
  * Number of partitions into which the topic is divided.
  * Type: `integer`
  * Range: ≥ 1
* **schemaText**
  * Schema used for message serialization. Optional as some topics may not have associated schemas.
  * Type: `string`
* **schemaType**
  * Schema used for message serialization.
  * $ref: [#/definitions/schemaType](topic.md#schematype)
* **cleanupPolicies**
  * Topic clean up policies. For Kafka - `cleanup.policy` configuration.
  * Type: `array`
    * **Items**
    * $ref: [#/definitions/cleanupPolicy](topic.md#cleanuppolicy)
* **retentionTime**
  * Retention time in milliseconds. For Kafka - `retention.ms` configuration.
  * Type: `integer`
* **replicationFactor**
  * Replication Factor in integer (more than 1).
  * Type: `integer`
* **maximumMessageSize**
  * Maximum message size in bytes. For Kafka - `max.message.bytes` configuration.
  * Type: `integer`
* **minimumInSyncReplicas**
  * Minimum number replicas in sync to control durability. For Kafka - `min.insync.replicas` configuration.
  * Type: `integer`
* **retentionSize**
  * Maximum size of a partition in bytes before old data is discarded. For Kafka - `retention.bytes` configuration.
  * Type: `integer`
  * Default: _"-1"_
* **owner**
  * Owner of this topic.
  * $ref: [../../type/entityReference.json](../types/entityreference.md)
* **followers**
  * Followers of this table.
  * $ref: [../../type/entityReference.json#/definitions/entityReferenceList](../types/entityreference.md#entityreferencelist)
* **tags**
  * Tags for this table.
  * Type: `array`
    * **Items**
    * $ref: [../../type/tagLabel.json](../types/taglabel.md)
* **href**
  * Link to the resource corresponding to this entity.
  * $ref: [../../type/basic.json#/definitions/href](../types/basic.md#href)
* **changeDescription**
  * Change that lead to this version of the entity.
  * $ref: [../../type/entityHistory.json#/definitions/changeDescription](../types/entityhistory.md#changedescription)
* **deleted**
  * When `true` indicates the entity has been soft deleted.
  * Type: `boolean`
  * Default: _false_

### Type definitions in this schema


#### topicName

* Name that identifies a topic.
* Type: `string`
* Length: between 1 and 128


* Name that identifies a topic.
* Type: `string`
* The value must match this pattern: `^[^.]*$`
* Length: between 1 and 128

#### schemaType

* Schema type used for the message.
* The value is restricted to the following:
  1. _"Avro"_
  2. _"Protobuf"_
  3. _"JSON"_
  4. _"Other"_

#### cleanupPolicy


* Topic clean up policy. For Kafka - `cleanup.policy` configuration.
* The value is restricted to the following:
  1. _"delete"_
  2. _"compact"_

## _This document was updated on: Tuesday, January 25, 2022_

* Topic clean up policy. For Kafka - `cleanup.policy` configuration.
* The value is restricted to the following:
  1. _"delete"_
  2. _"compact"_

#### topicConfig

* Contains key/value pair of topic configuration.
* Type: `object`

_This document was updated on: Monday, March 7, 2022_

_This document was updated on: Wednesday, March 9, 2022_