Managing Schemas

Schemas, like other entities in Pulsar, can be managed using the admin API.

Schema resources

A Pulsar schema is a fairly simple data structure stored in Pulsar for representing the structure of messages stored in a Pulsar topic. The schema structure consists of:

• Name: A schema's name is the topic that the schema is associated to.
• Type: A schema type represents the type of the schema. The predefined schema types can be found here. If it is a customized schema, it is left as an empty string.
• Payload: It is a binary representation of the schema. How to interpret it is up to the implementation of the schema.
• Properties: It is a user defined properties as a string/string map. Applications can use this bag for carrying any application specific logics. Possible properties might be the Git hash associated with the schema, an environment string like dev or prod, etc.

All the schemas are versioned with versions. So you can retrieve the schema definition of a given version if the version is not deleted.

Upload Schema

pulsar-admin

You can upload a new schema using the upload subcommand:

$ pulsar-admin schemas upload <topic-name> --filename /path/to/schema-definition-file

The schema definition file should contain following json string on defining how the schema look like:

{
    "type": "STRING",
    "schema": "",
    "properties": {
        "key1" : "value1"
    }
}

An example of the schema definition file can be found at SchemaExample.

REST

POST /admin/v2/schemas/:tenant/:namespace/:topic/schema/uploadSchema

Get Schema

pulsar-admin

You can get the latest version of Schema using the get subcommand.

$ pulsar-admin schemas get <topic-name>
{
    "version": 0,
    "type": "String",
    "timestamp": 0,
    "data": "string",
    "properties": {
        "property1": "string",
        "property2": "string"
    }
}

You can also retrieve the Schema of a given version by specifying --version option.

$ pulsar-admin schemas get <topic-name> --version <version>

REST API

Retrieve the latest version of the schema:

GET /admin/v2/schemas/:tenant/:namespace/:topic/schema/getSchema

Retrieve the schema of a given version:

GET /admin/v2/schemas/:tenant/:namespace/:topic/schema/:version/getSchema

Delete Schema

pulsar-admin

You can delete a schema using the delete subcommand.

$ pulsar-admin schemas delete <topic-name>

REST API

DELETE /admin/v2/schemas/:tenant/:namespace/:topic/schema/deleteSchema