> ## 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 using the Pulsar Node.js client

This document describes how to connect to a cluster using a Node.js client, and use the Node.js producer and consumer to produce and consume messages to and from a topic. The Node.js client supports connecting to a StreamNative cluster using either [OAuth2](#use-oauth2) or [API Keys](#use-apikeys) authentication.

<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>

## 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

For a complete example of how to connect to a cluster using the Pulsar Node.js client, see [Node.js client examples](https://github.com/streamnative/cloud-manager/tree/master/ui/src/data/code/clients/nodejs).

#### Create a Node.js consumer to consume messages

You can create and configure a Node.js consumer to consume messages using Token authentication as follows. For more information about the placeholders in the code sample, see [parameters for Token authentication](/cloud/build/pulsar-clients/cloud-connect-nodejs#parameters-for-token-authentication).

```javascript theme={null}
const Pulsar = require('pulsar-client')

const service_url = '${brokerServiceURL}'
const auth_params = '${apikey}'

;(async () => {
  const auth = new Pulsar.AuthenticationToken({
    token: auth_params,
  })

  const client = new Pulsar.Client({
    serviceUrl: service_url,
    authentication: auth,
    operationTimeoutSeconds: 30,
  })

  const consumer = await client.subscribe({
    topic: 'persistent://${tenant}/${namespace}/${topic}',
    subscription: '${subscription}',
    subscriptionInitialPosition: 'Earliest',
  })

  for (let i = 0; i < 10; i += 1) {
    const msg = await consumer.receive()
    console.log(msg.getData().toString())
    await consumer.acknowledge(msg)
  }

  await consumer.close()
  await client.close()
})()
```

#### Create a Node.js producer to produce messages

You can create and configure a Node.js producer to produce messages using Token authentication as follows. For more information about the placeholders in the code sample, see [parameters for Token authentication](/cloud/build/pulsar-clients/cloud-connect-nodejs#parameters-for-token-authentication).

```javascript theme={null}
const Pulsar = require('pulsar-client')

const service_url = '${brokerServiceURL}'
const auth_params = '${apikey}'

;(async () => {
  const auth = new Pulsar.AuthenticationToken({
    token: auth_params,
  })

  const client = new Pulsar.Client({
    serviceUrl: service_url,
    authentication: auth,
    operationTimeoutSeconds: 30,
  })

  const producer = await client.createProducer({
    topic: 'persistent://${tenant}/${namespace}/${topic}',
    sendTimeoutMs: 30000,
    batchingEnabled: true,
  })

  for (let i = 0; i < 10; i += 1) {
    const msg = `my-message-${i}`
    await producer.send({
      data: Buffer.from(msg),
    })
    console.log(`Sent message: ${msg}`)
  }
  await producer.flush()

  await producer.close()
  await client.close()
})()
```

#### Parameters for Token authentication

* `${brokerServiceURL}`: the broker service URL of your StreamNative cluster.
* `${apikey}`: an API key of your service account.
* `${tenant}/${namespace}/${topic}`: the full name of the topic for message production & consumption. It is a combination of the tenant name, the namespace name and the topic name.
* `${subscription}`: the name of the subscription that will determine how messages are delivered.

## 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

For a complete example of how to connect to a cluster using the Pulsar Node.js client, see [Node.js client examples](https://github.com/streamnative/cloud-manager/tree/master/ui/src/data/code/clients/nodejs).

#### Create a Node.js consumer to consume messages

You can create and configure a Node.js consumer to consume messages using the OAuth2 credential file as follows. For more information about the placeholders in the code sample, see [parameters for OAuth2 authentication](/cloud/build/pulsar-clients/cloud-connect-nodejs#parameters-for-oauth2-authentication).

```javascript theme={null}
const Pulsar = require('pulsar-client')
const issuer_url = 'https://auth.streamnative.cloud/'
const private_key = '/YOUR-KEY-FILE-PATH' // Absolute file path of your downloaded key file without file:// prefix
const audience = 'urn:sn:pulsar:${orgName}:${instanceName}'
const service_url = '${brokerServiceURL}'

;(async () => {
  const params = {
    issuer_url: issuer_url,
    private_key: private_key,
    audience: audience,
  }

  const auth = new Pulsar.AuthenticationOauth2(params)

  const client = new Pulsar.Client({
    serviceUrl: service_url,
    authentication: auth,
    operationTimeoutSeconds: 30,
  })

  const consumer = await client.subscribe({
    topic: 'persistent://${tenant}/${namespace}/${topic}',
    subscription: '${subscription}',
    subscriptionInitialPosition: 'Earliest',
  })

  for (let i = 0; i < 10; i += 1) {
    const msg = await consumer.receive()
    console.log(msg.getData().toString())
    await consumer.acknowledge(msg)
  }

  await consumer.close()
  await client.close()
})()
```

#### Create a Node.js producer to produce messages

You can create and configure a Node.js producer to produce messages using the OAuth2 credential file as follows. For more information about the placeholders in the code sample, see [parameters for OAuth2 authentication](/cloud/build/pulsar-clients/cloud-connect-nodejs#parameters-for-oauth2-authentication).

```javascript theme={null}
const Pulsar = require('pulsar-client')
const issuer_url = 'https://auth.streamnative.cloud/'
const private_key = '/YOUR-KEY-FILE-PATH' // Absolute file path of your downloaded key file without file:// prefix
const audience = 'urn:sn:pulsar:${orgName}:${instanceName}'
const service_url = '${brokerServiceURL}'

;(async () => {
  const params = {
    issuer_url: issuer_url,
    private_key: private_key,
    audience: audience,
  }

  const auth = new Pulsar.AuthenticationOauth2(params)

  const client = new Pulsar.Client({
    serviceUrl: service_url,
    authentication: auth,
    operationTimeoutSeconds: 30,
  })

  const producer = await client.createProducer({
    topic: 'persistent://${tenant}/${namespace}/${topic}',
    sendTimeoutMs: 30000,
    batchingEnabled: true,
  })

  for (let i = 0; i < 10; i += 1) {
    const msg = `my-message-${i}`
    await producer.send({
      data: Buffer.from(msg),
    })
    console.log(`Sent message: ${msg}`)
  }
  await producer.flush()

  await producer.close()
  await client.close()
})()
```

#### Parameters for OAuth2 authentication

* `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).
* `${brokerServiceURL}`: the broker service URL of your StreamNative cluster.
* `${tenant}/${namespace}/${topic}`: the full name of the topic for message production & consumption. It is a combination of the tenant name, the namespace name and the topic name.
* `${subscription}`: the name of the subscription that will determine how messages are delivered.