> ## Documentation Index
> Fetch the complete documentation index at: https://docs.streamnative.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Connect to your cluster in Spring applications

This document describes how to connect to a cluster in Spring applications, and use the producer and consumer to produce and consume messages to and from a topic. You can use either [OAuth2](#use-oauth2) or [API Keys](#use-apikeys) authentication in Spring applications.

<Note title="Note">
  This document assumes that you have created a StreamNative cluster and a service account, and have granted the service account `produce` and `consume` permissions to the namespace for the target topic.
</Note>

## Prerequisites

See the [minimum supported versions required for the underlying libraries](https://docs.spring.io/spring-pulsar/docs/current/reference/html/#_minimum_supported_versions) for more details.

## Connect to your cluster using API keys

<span id="use-apikeys" />

To connect a StreamNative cluster using [API keys](/cloud/security/authentication/service-accounts/use-api-keys/api-keys-overview), follow these steps.

### Step 1: Get the broker service URL of your cluster

To get the service URL(s) of a StreamNative cluster, follow these steps.

<Tabs>
  <Tab title="StreamNative Console">
    1. Navigate to the **Cluster Dashboard** page by [switching to the cluster workspace](/cloud/get-started/cloud-console#switch-a-cluster).

    2. On the **Cluster Dashboard** page, click **Details** tab.

    3. You will see the available service URLs in the **Access Points** area.

    4. You can click **Copy** at the end of the row of the service URL that you want to use.
  </Tab>
</Tabs>

### Step 2: Create an API key of your service account

<Note title="Note">
  Before using an API key, verify that the service account is authorized to access the resources, such as tenants, namespaces, and topics.
</Note>

You can follow the instructions to [create an API key](/cloud/security/authentication/service-accounts/use-api-keys/api-keys-overview#using-api-keys-to-connect-to-your-cluster) for the service account you choose to use.

### Step 3: Connect to your cluster

#### Configure a YAML file

Set the following configurations in the code of your Spring applications.

```yaml theme={null}
spring:
  pulsar:
    client:
      service-url: ${brokerServiceURL}
      auth-plugin-class-name: org.apache.pulsar.client.impl.auth.AuthenticationToken
      authentication:
        token: ${apikey}
```

* `${brokerServiceURL}l`: the broker service URL of your StreamNative cluster.
* `${apikey}`: an API key of your service account.

#### Consume messages

You can consume messages using Token authentication in your Spring application as follows.

```java theme={null}
@SpringBootApplication
public class PulsarBootHelloWorld {

    public static void main(String[] args) {
        SpringApplication.run(PulsarBootHelloWorld.class, args);
    }

    @PulsarListener(subscriptionName = "${subscription}", topics = "persistent://${tenant}/${namespace}/${topic}")
    void listen(String message) {
        System.out.println("Message Received: " + message);
    }

}
```

#### Produce messages

You can produce messages using Token authentication in your Spring application as follows.

```java theme={null}
@SpringBootApplication
public class PulsarBootHelloWorld {

    public static void main(String[] args) {
        SpringApplication.run(PulsarBootHelloWorld.class, args);
    }

    @Bean
    ApplicationRunner runner(PulsarTemplate<String> pulsarTemplate) {
        return (args) -> pulsarTemplate.send("persistent://${tenant}/${namespace}/${topic}", "Hello Pulsar World!");
    }

}
```

For a complete example of how to connect to a cluster in a Spring application, see [Spring client examples](https://github.com/streamnative/cloud-manager/tree/master/ui/src/data/code/clients/spring).

## Connect to your cluster using OAuth2 authentication

<span id="use-oauth2" />

To connect a StreamNative cluster using OAuth2 authentication, follow these steps.

### Step 1: Get the broker service URL of your cluster

To get the service URL(s) of a StreamNative cluster, follow these steps.

<Tabs>
  <Tab title="StreamNative Console">
    1. Navigate to the **Cluster Dashboard** page by [switching to the cluster workspace](/cloud/get-started/cloud-console#switch-a-cluster).

    2. On the **Cluster Dashboard** page, click **Details** tab.

    3. You will see the available service URLs in the **Access Points** area.

    4. You can click **Copy** at the end of the row of the service URL that you want to use.
  </Tab>
</Tabs>

### Step 2: Get the OAuth2 credential file of your service account

To get an OAuth2 credential file of a service account through the StreamNative Console, follow these steps.

1. On the left navigation pane, click **Service Accounts**.

2. In the row of the service account you want to use, in the **Key File** column, click the **Download** icon to download the OAuth2 credential file to your local directory.

   The OAuth2 credential file should be something like this:

   ```json theme={null}
   {
     "type": "SN_SERVICE_ACCOUNT",
     "client_id": "CLIENT_ID",
     "client_secret": "CLIENT_SECRET",
     "client_email": "test@auth.streamnative.cloud",
     "issuer_url": "https://auth.streamnative.cloud"
   }
   ```

### Step 3: Connect to your cluster

#### Configure a YAML file

Set the following configurations in the code of your Spring applications.

```yaml theme={null}
spring:
  pulsar:
    client:
      service-url: ${brokerServiceURL}
      auth-plugin-class-name: org.apache.pulsar.client.impl.auth.oauth2.AuthenticationOAuth2
      authentication:
        issuer-url: 'https://auth.streamnative.cloud/'
        private-key: '/YOUR-KEY-FILE-PATH' # TODO Absolute file path of your downloaded key file
        audience: 'urn:sn:pulsar:${orgName}:${instanceName}'
```

* `service-url`: the broker service URL of your StreamNative cluster.
* `private-key`: your downloaded OAuth2 credential. This parameter supports the following two pattern formats:
  * `file:///path/to/file`: the path to your downloaded OAuth2 credential file.
  * `data:application/json;base64,<base64-encoded value>`: the credential file content encoded into Base64 format.
* `audience`: the [Uniform Resource Name (URN)](/cloud/references/glossary#urn), which is a combination of the `urn:sn:pulsar`, your organization name, and your Pulsar instance name.
  * `${orgName}`: the name of your [organization](/cloud/references/glossary#organization).
  * `${instanceName}`: the name of your [instance](/cloud/references/glossary#instance).

#### Consume messages

You can consume messages using OAuth2 authentication in your Spring application as follows.

```java theme={null}
import org.springframework.pulsar.annotation.PulsarListener;

@SpringBootApplication
public class PulsarBootHelloWorld {

    public static void main(String[] args) {
        SpringApplication.run(PulsarBootHelloWorld.class, args);
    }

    @PulsarListener(subscriptionName = "${subscription}", topics = "persistent://${tenant}/${namespace}/${topic}")
    void listen(String message) {
        System.out.println("Message Received: " + message);
    }

}
```

#### Produce messages

You can produce messages using OAuth2 authentication in your Spring application as follows.

```java theme={null}
import org.springframework.pulsar.core.PulsarTemplate;

@SpringBootApplication
public class PulsarBootHelloWorld {

    public static void main(String[] args) {
        SpringApplication.run(PulsarBootHelloWorld.class, args);
    }

    @Bean
    ApplicationRunner runner(PulsarTemplate<String> pulsarTemplate) {
        return (args) -> pulsarTemplate.send("persistent://${tenant}/${namespace}/${topic}", "Hello Pulsar World!");
    }

}
```

For a complete example of how to connect to a cluster in your Spring application, see [Spring client examples](https://github.com/streamnative/cloud-manager/tree/master/ui/src/data/code/clients/spring).