> ## 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 C++ client

This document describes how to connect to a cluster using a C++ client, and use the C++ producer and consumer to produce and consume messages to and from a topic. The C++ 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 C++ client, see [C++ client examples](https://github.com/streamnative/cloud-manager/tree/master/ui/src/data/code/clients/cpp).

#### Create a C++ consumer to consume messages

You can create and configure a C++ 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-cpp#parameters-for-token-authentication).

```cpp theme={null}
#include <pulsar/Client.h>
#include <thread>

using namespace pulsar;

int main() {
    ClientConfiguration clientConfig;
    clientConfig.setAuth(AuthToken::createWithToken("${apikey}"));
    Client client("${brokerServiceURL}", clientConfig);

    Consumer consumer;
    ConsumerConfiguration consumerConfig;
    consumerConfig.setSubscriptionInitialPosition(InitialPositionEarliest);
    Result result = client.subscribe("persistent://${tenant}/${namespace}/${topic}", "${subscription}", consumerConfig, consumer);
    if (result != ResultOk) {
        std::cout << "Failed to subscribe: " << result << std::endl;
        return -1;
    }

    Message msg;
    int ctr = 0;

    while (ctr < 10) {
        consumer.receive(msg);
        std::cout << "Received: " << msg
            << "  with payload '" << msg.getDataAsString() << "'" << std::endl;

        consumer.acknowledge(msg);
        ctr++;
    }

    std::cout << "Finished consuming synchronously!" << std::endl;

    client.close();
    return 0;
}
```

#### Create a C++ producer to produce messages

You can create and configure a C++ 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-cpp#parameters-for-token-authentication).

```cpp theme={null}
#include <pulsar/Client.h>
#include <thread>

using namespace pulsar;

int main() {
    ClientConfiguration config;
    config.setAuth(AuthToken::createWithToken("${apikey}"));
    Client client("${brokerServiceURL}", config);

    Producer producer;
    Result result = client.createProducer("persistent://${tenant}/${namespace}/${topic}", producer);
    if (result != ResultOk) {
        std::cout << "Error creating producer: " << result << std::endl;
        return -1;
    }

    int ctr = 0;
    while (ctr < 10) {
        std::string content = "msg" + std::to_string(ctr);
        Message msg = MessageBuilder().setContent(content).setProperty("x", "1").build();
        Result result = producer.send(msg);
        if (result != ResultOk) {
            std::cout << "The message " << content << " could not be sent, received code: " << result << std::endl;
        } else {
            std::cout << "The message " << content << " sent successfully" << std::endl;
        }

        std::this_thread::sleep_for(std::chrono::milliseconds(100));
        ctr++;
    }

    std::cout << "Finished producing synchronously!" << std::endl;

    client.close();
    return 0;
}
```

#### 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 through the Pulsar C++ client, see [C++ client examples](https://github.com/streamnative/cloud-manager/tree/master/ui/src/data/code/clients/cpp).

#### Create a C++ consumer to consume messages

You can create and configure a C++ 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-cpp#parameters-for-oauth2-authentication).

```cpp theme={null}
#include <pulsar/Client.h>
#include <thread>

using namespace pulsar;

int main() {
    ClientConfiguration clientConfig;
     // Replace YOUR-KEY-FILE-PATH with the absolute path or your downloaded JSON key file:
   std::string params = R"({
    "issuer_url": "https://auth.streamnative.cloud/",
    "private_key": "{{ file://YOUR-KEY-FILE-PATH }}",
    "audience": "urn:sn:pulsar:${orgName}:${instanceName}"})";

    clientConfig.setAuth(pulsar::AuthOauth2::create(params));
    Client client("${brokerServiceURL}", clientConfig);

    Consumer consumer;
    ConsumerConfiguration consumerConfig;
    consumerConfig.setSubscriptionInitialPosition(InitialPositionEarliest);
    Result result = client.subscribe("persistent://${tenant}/${namespace}/${topic}", "${subscription}", consumerConfig, consumer);
    if (result != ResultOk) {
        std::cout << "Failed to subscribe: " << result << std::endl;
        return -1;
    }

    Message msg;
    int ctr = 0;

    while (ctr < 10) {
        consumer.receive(msg);
        std::cout << "Received: " << msg
            << "  with payload '" << msg.getDataAsString() << "'" << std::endl;

        consumer.acknowledge(msg);
        ctr++;
    }

    std::cout << "Finished consuming synchronously!" << std::endl;

    client.close();
    return 0;
}
```

#### Create a C++ producer to produce messages

You can create and configure a C++ 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-cpp#parameters-for-oauth2-authentication).

```cpp theme={null}
#include <pulsar/Client.h>
#include <thread>

using namespace pulsar;

int main() {
    ClientConfiguration config;
    // Replace YOUR-KEY-FILE-PATH with the absolute path or your downloaded JSON key file:
    std::string params = R"({
    "issuer_url": "https://auth.streamnative.cloud/",
    "private_key": "/YOUR-KEY-FILE-PATH",
    "audience": "urn:sn:pulsar:${orgName}:${instanceName}"})";

    config.setAuth(pulsar::AuthOauth2::create(params));
    Client client("${brokerServiceURL}", config);

    Producer producer;
    Result result = client.createProducer("persistent://${tenant}/${namespace}/${topic}", producer);
    if (result != ResultOk) {
        std::cout << "Error creating producer: " << result << std::endl;
        return -1;
    }

    int ctr = 0;
    while (ctr < 10) {
        std::string content = "msg" + std::to_string(ctr);
        Message msg = MessageBuilder().setContent(content).setProperty("x", "1").build();
        Result result = producer.send(msg);
        if (result != ResultOk) {
            std::cout << "The message " << content << " could not be sent, received code: " << result << std::endl;
        } else {
            std::cout << "The message " << content << " sent successfully" << std::endl;
        }

        std::this_thread::sleep_for(std::chrono::milliseconds(100));
        ctr++;
    }

    std::cout << "Finished producing synchronously!" << std::endl;

    client.close();
    return 0;
}
```

#### 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.