> ## 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 Pulsar cluster using C++ client

This document provides examples about how to use the Pulsar C++ client to connect to a Pulsar cluster through a token or an OAuth2 credential file.

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

## Connect to a Pulsar cluster using a token

This section describes how to connect to you Pulsar cluster using a token.

### Prerequisites

* [Get the service URL](/private-cloud/v1/build/connect-prepare#get-the-service-url).
* [Get a service account token](/private-cloud/v1/build/connect-prepare#get-a-service-account-token).

### Steps

To connect to your Pulsar cluster using a token, follow these steps.

1. Connect to the Pulsar cluster.

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

   using namespace pulsar;

   int main() {
     ClientConfiguration config;
     config.setAuth(AuthToken::create("AUTH_PARAMS"));
     Client client("SERVICE_URL", config);

     client.close();
   }
   ```

   Set the `SERVICE_URL` and `AUTH_PARAMS` parameters based on the descriptions in the [prepare to connect to a Pulsar cluster](/private-cloud/v1/build/connect-prepare) user guide.

2. Create a C++ consumer and use the C++ consumer to consume messages.

   ```cpp theme={null}
   int main(int argc, char *argv[]) {
     ClientConfiguration config;
     std::string oauthParams = argv[2];

     config.setAuth(AuthToken::create("AUTH_PARAMS"));

     Client client(argv[1], config);

     Consumer consumer;
     Result result = client.subscribe("your-topic", "your-sub-name", consumer);
     if (result != ResultOk) {
       std::cout << "Failed to subscribe: " << result << "\n";
       return -1;
     }

     Message msg;
     while (true) {
       consumer.receive(msg);
       std::cout << "Received: " << msg << "  with payload '" << msg.getDataAsString() << "'" << "\n";

       consumer.acknowledge(msg);
     }
   }
   ```

3. Create a C++ producer and use the C++ producer to produce messages.

   ```cpp theme={null}
   int main(int argc, char *argv[]) {
     ClientConfiguration config;
     std::string oauthParams = argv[2];

     config.setAuth(AuthToken::create("AUTH_PARAMS"));

     Client client(argv[1], config);

     Producer producer;
     Result result = client.createProducer("your-topic", producer);
     if (result != ResultOk) {
       std::cout << "Error creating producer: " << result << "\n";
       return -1;
     }

     // Send synchronously
     Message msg = MessageBuilder().setContent("content").build();
     Result res = producer.send(msg);
     std::cout << "Message sent: " << res << "\n";

     client.close();
   }
   ```

## Connect to a Pulsar cluster using an OAuth2 credential file

To connect to your Pulsar cluster using an OAuth2 credential file, follow these steps.

1. Generate the App credentials by following similar instructions in [configure OAuth2 authentication](/private-cloud/v1/operating-streamnative-platform/security/oauth2-auth).

2. Save the App credentials into an OAuth2 credential file.

3. Connect to your Pulsar cluster through the OAuth2 credential file.

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

   using namespace pulsar;

   int main() {
     ClientConfiguration config;
     std::string oauthParams = R"({
     "issuer_url": "your-issuer-url",
     "private_key": "file:///path/to/private-key-file.json",
     "audience": "your-audience"})";

     config.setAuth(pulsar::AuthOauth2::create(oauthParams));

     Client client("pulsar-service-url", config);
     client.close();
   }
   ```

   * `issuerUrl`: the URL of your OAuth2 identity provider.
   * `private_key`: the path to your OAuth2 credential file.
   * `audience`: the `audience` of your Pulsar cluster.
   * `client`: the URL of your Pulsar cluster.

4. Create a C++ consumer and use the C++ consumer to consume messages.

   ```cpp theme={null}
   int main(int argc, char *argv[]) {
     ClientConfiguration config;
     std::string oauthParams = argv[2];

     config.setAuth(pulsar::AuthOauth2::create(oauthParams));

     Client client(argv[1], config);

     Consumer consumer;
     Result result = client.subscribe("your-topic", "your-sub-name", consumer);
     if (result != ResultOk) {
       std::cout << "Failed to subscribe: " << result << "\n";
       return -1;
     }

     Message msg;
     while (true) {
       consumer.receive(msg);
       std::cout << "Received: " << msg << "  with payload '" << msg.getDataAsString() << "'" << "\n";

       consumer.acknowledge(msg);
     }
   }
   ```

5. Create a C++ producer and use the C++ producer to produce messages.

   ```cpp theme={null}
   int main(int argc, char *argv[]) {
     ClientConfiguration config;
     std::string oauthParams = argv[2];

     config.setAuth(pulsar::AuthOauth2::create(oauthParams));

     Client client(argv[1], config);

     Producer producer;
     Result result = client.createProducer("your-topic", producer);
     if (result != ResultOk) {
       std::cout << "Error creating producer: " << result << "\n";
       return -1;
     }

     // Send synchronously
     Message msg = MessageBuilder().setContent("content").build();
     Result res = producer.send(msg);
     std::cout << "Message sent: " << res << "\n";

     client.close();
   }
   ```