versioned_docs/version-2.4.0/schema-manage.md

id: schema-manage title: Manage schema sidebar_label: “Manage schema” original_id: schema-manage

import Tabs from '@theme/Tabs';
import TabItem from '@theme/TabItem';

This guide demonstrates the ways to manage schemas:

Automatically
- Schema AutoUpdate
Manually
- Schema manual management
- Custom schema storage

Schema AutoUpdate

If a schema passes the schema compatibility check, Pulsar producer automatically updates this schema to the topic it produces by default.

AutoUpdate for producer

For a producer, the AutoUpdate happens in the following cases:

If a topic doesn’t have a schema, Pulsar registers a schema automatically.
If a topic has a schema:
- If a producer doesn’t carry a schema:
- If isSchemaValidationEnforced or schemaValidationEnforced is disabled in the namespace to which the topic belongs, the producer is allowed to connect to the topic and produce data.
- If isSchemaValidationEnforced or schemaValidationEnforced is enabled in the namespace to which the topic belongs, the producer is rejected and disconnected.
- If a producer carries a schema:
A broker performs the compatibility check based on the configured compatibility check strategy of the namespace to which the topic belongs.
- If it is a new schema and it passes the compatibility check, the broker registers a new schema automatically for the topic.
- If the schema does not pass the compatibility check, the broker does not register a schema.

AutoUpdate Producer

AutoUpdate for consumer

For a consumer, the AutoUpdate happens in the following cases:

If a consumer connects to a topic without a schema (which means the consumer receiving raw bytes), the consumer can connect to the topic successfully without doing any compatibility check.
If a consumer connects to a topic with a schema:
- If the topic is idle (no producers, no entries, no other consumers and no registered schemas), the broker registers a schema for the topic automatically.
- If the topic is not idle, the broker verifies if the schema provided by the consumer is compatible with the registered schema of the topic.
- If the schema passes the compatibility check, the consumer can connect to the topic and receive messages.
- If the schema does not pass the compatibility check, the consumer is rejected and disconnected.

AutoUpdate Producer

Manage AutoUpdate strategy

You can use the pulsar-admin command to manage the AutoUpdate strategy as below:

Disable AutoUpdate
Adjust compatibility

Disable AutoUpdate

To disable AutoUpdate on a namespace, you can use the pulsar-admin command.


bin/pulsar-admin namespaces set-schema-autoupdate-strategy --disabled tenant/namespace

Once the AutoUpdate is disabled, you can only register a new schema using the pulsar-admin command.

Adjust compatibility

To adjust the schema compatibility level on a namespace, you can use the pulsar-admin command.


bin/pulsar-admin namespaces set-schema-autoupdate-strategy --compatibility <compatibility-level> tenant/namespace

Schema validation

By default, schemaValidationEnforced is disabled for producers:

This means a producer without a schema can produce any kind of messages to a topic with schemas, which may result in producing trash data to the topic.
This allows non-java language clients that don’t support schema can produce messages to a topic with schemas.

However, if you want a stronger guarantee on the topics with schemas, you can enable schemaValidationEnforced across the whole cluster or on a per-namespace basis.

Enable schema validation

To enable schemaValidationEnforced on a namespace, you can use the pulsar-admin command.


bin/pulsar-admin namespaces set-schema-validation-enforce --enable tenant/namespace

Disable schema validation

To disable schemaValidationEnforced on a namespace, you can use the pulsar-admin command.


bin/pulsar-admin namespaces set-schema-validation-enforce --disable tenant/namespace

Schema manual management

To manage schemas, you can use one of the following methods.

Method	Description
Admin CLI	You can use the `pulsar-admin` tool to manage Pulsar schemas, brokers, clusters, sources, sinks, topics, tenants and so on. For more information about how to use the `pulsar-admin` tool, see here.
REST API	Pulsar exposes schema related management API in Pulsar’s admin RESTful API. You can access the admin RESTful endpoint directly to manage schemas. For more information about how to use the Pulsar REST API, see here.
Java Admin API	Pulsar provides Java admin library.

Upload a schema

To upload (register) a new schema for a topic, you can use one of the following methods.

<Tabs
  defaultValue="Admin CLI"
  values={[{"label":"Admin CLI","value":"Admin CLI"},{"label":"REST API","value":"REST API"},{"label":"Java Admin API","value":"Java Admin API"}]}>

<TabItem value="Admin CLI">

Use the `upload` subcommand.

```bash

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

```

The `schema-definition-file` is in JSON format.

```json

{
    "type": "<schema-type>",
    "schema": "<an-utf8-encoded-string-of-schema-definition-data>",
    "properties": {} // the properties associated with the schema
}

```

The `schema-definition-file` includes the following fields:

| Field |  Description |
| --- | --- |
|  `type`  |   The schema type. |
| `schema` | The schema definition data, which is encoded in UTF 8 charset. <li>If the schema is a **primitive** schema, this field should be blank. </li><li>If the schema is a **struct** schema, this field should be a JSON string of the Avro schema definition. </li> |
|  `properties`  |  The additional properties associated with the schema. |

Here are examples of the `schema-definition-file` for a JSON schema.

**Example 1**

```json

{
    "type": "JSON",
    "schema": "{\"type\":\"record\",\"name\":\"User\",\"namespace\":\"com.foo\",\"fields\":[{\"name\":\"file1\",\"type\":[\"null\",\"string\"],\"default\":null},{\"name\":\"file2\",\"type\":\"string\",\"default\":null},{\"name\":\"file3\",\"type\":[\"null\",\"string\"],\"default\":\"dfdf\"}]}",
    "properties": {}
}

```

**Example 2**

```json

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

```

</TabItem>
<TabItem value="REST API">

Send a `POST` request to this endpoint: {@inject: endpoint|POST|/admin/v2/schemas/:tenant/:namespace/:topic/schema|operation/uploadSchema?version=@pulsar:version_number@}

The post payload is in JSON format.

```json

{
    "type": "<schema-type>",
    "schema": "<an-utf8-encoded-string-of-schema-definition-data>",
    "properties": {} // the properties associated with the schema
}

```

The post payload includes the following fields:

| Field |  Description |
| --- | --- |
|  `type`  |   The schema type. |
| `schema` | The schema definition data, which is encoded in UTF 8 charset. <li>If the schema is a **primitive** schema, this field should be blank. </li><li>If the schema is a **struct** schema, this field should be a JSON string of the Avro schema definition. </li> |
|  `properties`  |  The additional properties associated with the schema. |

</TabItem>
<TabItem value="Java Admin API">

```java

void createSchema(String topic, PostSchemaPayload schemaPayload)

```

The `PostSchemaPayload` includes the following fields:

| Field |  Description |
| --- | --- |
|  `type`  |   The schema type. |
| `schema` | The schema definition data, which is encoded in UTF 8 charset. <li>If the schema is a **primitive** schema, this field should be blank. </li><li>If the schema is a **struct** schema, this field should be a JSON string of the Avro schema definition. </li> |
|  `properties`  |  The additional properties associated with the schema. |

Here is an example of `PostSchemaPayload`:

```java

PulsarAdmin admin = …;

PostSchemaPayload payload = new PostSchemaPayload();
payload.setType("INT8");
payload.setSchema("");

admin.createSchema("my-tenant/my-ns/my-topic", payload);

```

</TabItem>

</Tabs>

Get a schema (latest)

To get the latest schema for a topic, you can use one of the following methods.

<Tabs
  defaultValue="Admin CLI"
  values={[{"label":"Admin CLI","value":"Admin CLI"},{"label":"REST API","value":"REST API"},{"label":"Java Admin API","value":"Java Admin API"}]}>

<TabItem value="Admin CLI">

Use the `get` subcommand.

```bash

$ pulsar-admin schemas get <topic-name>

{
    "version": 0,
    "type": "String",
    "timestamp": 0,
    "data": "string",
    "properties": {
        "property1": "string",
        "property2": "string"
    }
}

```

</TabItem>
<TabItem value="REST API">

Send a `GET` request to this endpoint: {@inject: endpoint|GET|/admin/v2/schemas/:tenant/:namespace/:topic/schema|operation/getSchema?version=@pulsar:version_number@}

Here is an example of a response, which is returned in JSON format.

```json

{
    "version": "<the-version-number-of-the-schema>",
    "type": "<the-schema-type>",
    "timestamp": "<the-creation-timestamp-of-the-version-of-the-schema>",
    "data": "<an-utf8-encoded-string-of-schema-definition-data>",
    "properties": {} // the properties associated with the schema
}

```

The response includes the following fields:

| Field |  Description |
| --- | --- |
|  `version`  |   The schema version, which is a long number. |
|  `type`  |   The schema type. |
|  `timestamp`  |   The timestamp of creating this version of schema. |
|  `data`  |   The schema definition data, which is encoded in UTF 8 charset. <li>If the schema is a </li>**primitive**<li>schema, this field should be blank. </li><li>If the schema is a </li>**struct**<li>schema, this field should be a JSON string of the Avro schema definition. </li> |
|  `properties`  |  The additional properties associated with the schema. |

</TabItem>
<TabItem value="Java Admin API">

```java

SchemaInfo createSchema(String topic)

```

The `SchemaInfo` includes the following fields:

| Field |  Description |
| --- | --- |
|  `name`  |   The schema name. |
|  `type`  |   The schema type. |
|  `schema`  |   A byte array of the schema definition data, which is encoded in UTF 8 charset. <li>If the schema is a </li>**primitive**<li>schema, this byte array should be empty. </li><li>If the schema is a </li>**struct**<li>schema, this field should be a JSON string of the Avro schema definition converted to a byte array. </li> |
|  `properties`  |  The additional properties associated with the schema. |

Here is an example of `SchemaInfo`:

```java

PulsarAdmin admin = …;

SchemaInfo si = admin.getSchema("my-tenant/my-ns/my-topic");

```

</TabItem>

</Tabs>

Get a schema (specific)

To get a specific version of a schema, you can use one of the following methods.

<Tabs
  defaultValue="Admin CLI"
  values={[{"label":"Admin CLI","value":"Admin CLI"},{"label":"REST API","value":"REST API"},{"label":"Java Admin API","value":"Java Admin API"}]}>

<TabItem value="Admin CLI">

Use the `get` subcommand.

```bash

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

```

</TabItem>
<TabItem value="REST API">

Send a `GET` request to a schema endpoint: {@inject: endpoint|GET|/admin/v2/schemas/:tenant/:namespace/:topic/schema/:version|operation/getSchema?version=@pulsar:version_number@}

Here is an example of a response, which is returned in JSON format.

```json

{
    "version": "<the-version-number-of-the-schema>",
    "type": "<the-schema-type>",
    "timestamp": "<the-creation-timestamp-of-the-version-of-the-schema>",
    "data": "<an-utf8-encoded-string-of-schema-definition-data>",
    "properties": {} // the properties associated with the schema
}

```

The response includes the following fields:

| Field |  Description |
| --- | --- |
|  `version`  |   The schema version, which is a long number. |
|  `type`  |   The schema type. |
|  `timestamp`  |   The timestamp of creating this version of schema. |
|  `data`  |   The schema definition data, which is encoded in UTF 8 charset. <li>If the schema is a </li>**primitive**<li>schema, this field should be blank. </li><li>If the schema is a </li>**struct**<li>schema, this field should be a JSON string of the Avro schema definition. </li> |
|  `properties`  |  The additional properties associated with the schema. |

</TabItem>
<TabItem value="Java Admin API">

```java

SchemaInfo createSchema(String topic, long version)

```

The `SchemaInfo` includes the following fields:

| Field |  Description |
| --- | --- |
|  `name`  |  The schema name. |
|  `type`  |  The schema type. |
|  `schema`  |   A byte array of the schema definition data, which is encoded in UTF 8. <li>If the schema is a </li>**primitive**<li>schema, this byte array should be empty. </li><li>If the schema is a </li>**struct**<li>schema, this field should be a JSON string of the Avro schema definition converted to a byte array. </li> |
|  `properties`  |  The additional properties associated with the schema. |

Here is an example of `SchemaInfo`:

```java

PulsarAdmin admin = …;

SchemaInfo si = admin.getSchema("my-tenant/my-ns/my-topic", 1L);

```

</TabItem>

</Tabs>

Extract a schema

To provide a schema via a topic, you can use the following method.

<Tabs
  defaultValue="Admin CLI"
  values={[{"label":"Admin CLI","value":"Admin CLI"}]}>

<TabItem value="Admin CLI">

Use the `extract` subcommand.

```bash

$ pulsar-admin schemas extract --classname <class-name> --jar <jar-path> --type <type-name>

```

</TabItem>

</Tabs>

Delete a schema

To delete a schema for a topic, you can use one of the following methods.

:::note

In any case, the delete action deletes all versions of a schema registered for a topic.

:::

<Tabs
  defaultValue="Admin CLI"
  values={[{"label":"Admin CLI","value":"Admin CLI"},{"label":"REST API","value":"REST API"},{"label":"Java Admin API","value":"Java Admin API"}]}>

<TabItem value="Admin CLI">

Use the `delete` subcommand.

```bash

$ pulsar-admin schemas delete <topic-name>

```

</TabItem>
<TabItem value="REST API">

Send a `DELETE` request to a schema endpoint: {@inject: endpoint|DELETE|/admin/v2/schemas/:tenant/:namespace/:topic/schema|operation/deleteSchema?version=@pulsar:version_number@}

Here is an example of a response, which is returned in JSON format.

```json

{
    "version": "<the-latest-version-number-of-the-schema>",
}

```

The response includes the following field:

Field | Description |
---|---|
`version` | The schema version, which is a long number. |

</TabItem>
<TabItem value="Java Admin API">

```java

void deleteSchema(String topic)

```

Here is an example of deleting a schema.

```java

PulsarAdmin admin = …;

admin.deleteSchema("my-tenant/my-ns/my-topic");

```

</TabItem>

</Tabs>

Custom schema storage

By default, Pulsar stores various data types of schemas in Apache BookKeeper deployed alongside Pulsar.

However, you can use another storage system if needed.

Implement

To use a non-default (non-BookKeeper) storage system for Pulsar schemas, you need to implement the following Java interfaces:

SchemaStorage interface
SchemaStorageFactory interface

SchemaStorage interface

The SchemaStorage interface has the following methods:


public interface SchemaStorage {
    // How schemas are updated
    CompletableFuture<SchemaVersion> put(String key, byte[] value, byte[] hash);

    // How schemas are fetched from storage
    CompletableFuture<StoredSchema> get(String key, SchemaVersion version);

    // How schemas are deleted
    CompletableFuture<SchemaVersion> delete(String key);

    // Utility method for converting a schema version byte array to a SchemaVersion object
    SchemaVersion versionFromBytes(byte[] version);

    // Startup behavior for the schema storage client
    void start() throws Exception;

    // Shutdown behavior for the schema storage client
    void close() throws Exception;
}

:::tip

For a complete example of schema storage implementation, see BookKeeperSchemaStorage class.

:::

SchemaStorageFactory interface

The SchemaStorageFactory interface has the following method:


public interface SchemaStorageFactory {
    @NotNull
    SchemaStorage create(PulsarService pulsar) throws Exception;
}

:::tip

For a complete example of schema storage factory implementation, see BookKeeperSchemaStorageFactory class.

:::

Deploy

To use your custom schema storage implementation, perform the following steps.

Package the implementation in a JAR file.
Add the JAR file to the lib folder in your Pulsar binary or source distribution.
Change the schemaRegistryStorageClassName configuration in broker.conf to your custom factory class.
Start Pulsar.