Connect with the C++ driver

Because Astra DB is based on Apache Cassandra®, you can use Cassandra drivers to connect to your Astra DB Classic databases.

To use the C++ driver, you need to install the driver and its dependencies, and then connect the driver to your Astra DB Classic database. Once connected, you can write scripts that use the driver to run commands against your database.

Prerequisites

Create a database.
Download your database’s Secure Connect Bundle (SCB).

For multi-region databases, download the Secure Connect Bundle (SCB) for a region that is geographically close to your application to reduce latency.

If you need to connect to multiple regions in the same application, you need the Secure Connect Bundle (SCB) for each region, and your driver code must instantiate one root object (session) for each region. For more information, see Best practices for Cassandra drivers.
Set the following environment variables:
- ASTRA_DB_ID: The database ID.
- ASTRA_DB_KEYSPACE: A keyspace in your database, such as default_keyspace.
- ASTRA_DB_APPLICATION_TOKEN: An application token with the Database Administrator role.

Driver authentication methods

There are two driver authentication methods: token authentication, or clientId and secret authentication.

Token authentication
Client ID and secret authentication

This authentication method is supported and recommended for most recent driver versions.

In your driver authentication code, pass the literal string token as the username and your application token value (AstraCS:…) as the password. For example:

("token", "AstraCS:...")

If you are on an older driver version that doesn’t support token authentication, then you might need to use clientId and secret.

When you generate an application token, download or copy the token.json that contains the following values:

{
  "clientId": "CLIENT_ID",
  "secret": "CLIENT_SECRET",
  "token": "APPLICATION_TOKEN"
}

In your driver authentication code, pass clientId as the username and secret as the password. For example:

("CLIENT_ID", "SECRET")

For more information, see Token details.

Install the C++ driver

Download and install the C++ driver.

If you choose to install an earlier version, make sure you choose a version that is compatible with Astra DB. For more information, see Cassandra drivers supported by DataStax.

Connect the C++ driver

In the root of your C++ project, create a connect_database.c file:
```
cd my_project
touch connect_database.c
```

Copy the following connection code into the connect_database.c file, and then replace PATH_TO_SCB with the absolute path to your database’s Secure Connect Bundle (SCB) (secure-connect-DATABASE_NAME.zip):

connect_database.c

#include <cassandra.h>
#include <stdio.h>

int main(int argc, char* argv[]) {
     /* Setup and connect to cluster /
     CassCluster cluster = cass_cluster_new();
     CassSession* session = cass_session_new();

     /* Setup driver to connect to the cloud using the secure connection bundle /
     const char secure_connect_bundle = "PATH_TO_SCB";
     if (cass_cluster_set_cloud_secure_connection_bundle(cluster, secure_connect_bundle) != CASS_OK) {
       fprintf(stderr, "Unable to configure cloud using the secure connection bundle: %s\n",
               secure_connect_bundle);
       return 1;
     }

     /* Set credentials provided when creating your database /
     cass_cluster_set_credentials(cluster, "token", "ASTRA_DB_APPLICATION_TOKEN");

     CassFuture connect_future = cass_session_connect(session, cluster);

     if (cass_future_error_code(connect_future) == CASS_OK) {
       /* Use the session to run queries /
     } else {
       / Handle error */
     }

     cass_future_free(connect_future);
     cass_cluster_free(cluster);
     cass_session_free(session);

     return 0;
   }

This code creates a CassStatement object to connect to your Astra DB database.

Don’t use the cass_cluster_set_contact_points() and cass_cluster_set_ssl() methods in conjunction with the cass_cluster_set_cloud_secure_connection_bundle() method.

Add code to your script that queries your database and prints the output to the console:

connect_database.c

/* Build statement and execute query */
const char_ query = "SELECT release_version FROM system.local";
CassStatement* statement = cass_statement_new(query, 0);

CassFuture* result_future = cass_session_execute(session, statement);

if (cass_future_error_code(result_future) == CASS_OK) {
  /* Retrieve result set and get the first row */
  const CassResult_ result = cass_future_get_result(result_future);
  const CassRow* row = cass_result_first_row(result);

  if (row) {
    const CassValue* value = cass_row_get_column_by_name(row, "release_version");

    const char* release_version;
    size_t release_version_length;
    cass_value_get_string(value, &release_version, &release_version_length);
    printf("release_version: '%._s'\n", (int)release_version_length, release_version);
  }

    cass_result_free(result);
  } else {
    /_ Handle error _/
    const char_ message;
    size_t message_length;
    cass_future_error_message(result_future, &message, &message_length);
    fprintf(stderr, "Unable to run query: '%.*s'\n", (int)message_length, message);
  }

  cass_statement_free(statement);
  cass_future_free(result_future);

Build and link your application against the DataStax C++ driver.
- Linux or macOS
- Windows
For static linking, use cassandra_static.a:
cc connect_database.c -I/path/to/cassandra.h -L/path/to/cassandra.so -lcassandra
Include these libraries in your Microsoft Visual Studio project by adding them to the project’s properties under Configuration Properties/Linker/Input/Additional Dependencies:
Link your application against cassandra.lib. For static linking, use cassandra_static.lib.

cassandra.dll must be in your application’s runtime path.
Run the compiled application.

The console output includes the release_version value from the system.local table.
Extend or modify this script to run other commands against your database or connect to other databases. For more information, see C++ driver documentation and DataStax-compatible Cassandra drivers.

Connect with the C++ driver

Prerequisites

Driver authentication methods

Install the C++ driver

Connect the C++ driver

See also

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