The objects available within our connector are accessible from the "cdata.powerbixmla" module. To use the module's objects directly:

1. Import the module as follows:
   

   import cdata.powerbixmla as mod

2. To establish a connection string, call the connect() method from the connector object using an appropriate connection string, such as:
   

   mod.connect("initiateoauth=GETANDREFRESH")

Connecting to Microsoft Power BI XMLA

To connect, set the Workspace property to a valid PowerBIXMLA workspace (ex: CData).

Authenticating to Microsoft Power BI XMLA

Azure AD

Azure AD is Microsoft’s multi-tenant, cloud-based directory and identity management service. It is user-based authentication that requires that you set AuthScheme to AzureAD.

Authentication to Azure AD over a Web application always requires the creation of a custom OAuth application. For details, see Creating a Custom OAuth App.

Desktop Applications

CData provides an embedded OAuth application that simplifies connection to Azure AD from a Desktop application.

You can also authenticate from a desktop application using a custom OAuth application. (For further information, see Creating a Custom OAuth App.) To authenticate via Azure AD, set these parameters:

• AuthScheme: AzureAD.

• Custom applications only:

  • OAuthClientId: The client Id assigned when you registered your custom OAuth application.
  • OAuthClientSecret: The client secret assigned when you registered your custom OAuth application.
  • CallbackURL: The redirect URI you defined when you registered your custom OAuth application.

When you connect, the connector opens Microsoft Power BI XMLA's OAuth endpoint in your default browser. Log in and grant permissions to the application.

The connector completes the OAuth process, obtaining an access token from Microsoft Power BI XMLA and using it to request data. The OAuth values are saved in the path specified in OAuthSettingsLocation. These values persist across connections.

When the access token expires, the connector refreshes it automatically.

Web Applications

To authenticate via Azure AD using a Web application, you must register a custom OAuth application with Microsoft Power BI XMLA (see Creating a Custom OAuth App). You can then use the connector to get and manage the OAuth token values.

Get an Azure AD OAuth Access Token

First, set these connection properties to obtain the OAuthAccessToken:

• AuthScheme: AzureAD.
• OAuthClientId: The client Id in your application settings.
• OAuthClientSecret: The client secret in your application settings.

Next, call stored procedures to complete the OAuth exchange:

1. Call the GetOAuthAuthorizationUrl stored procedure. Set the AuthMode input to WEB and set the CallbackURL input to the Redirect URI you specified in your application settings. If necessary, set the Permissions parameter to request custom permissions.
   The stored procedure returns the URL to the OAuth endpoint.
2. Open the URL, log in, and authorize the application. You are redirected back to the callback URL.
3. Call the GetOAuthAccessToken stored procedure. Set the AuthMode input to WEB. Set the Verifier input to the "code" parameter in the query string of the callback URL. If necessary, set the Permissions parameter to request custom permissions.

Once you have obtained the access and refresh tokens, you can connect to data and refresh the Azure AD access token either automatically or manually.

Automatic Refresh of the Azure AD OAuth Access Token

To have the connector automatically refresh the Azure AD OAuth access token, set the following parameters the first time you connect to data:

• AuthScheme: AzureAD.
• InitiateOAuth: REFRESH.
• OAuthClientId: The client Id in your application settings.
• OAuthClientSecret: The client secret in your application settings.
• OAuthAccessToken: The access token returned by GetOAuthAccessToken.
• OAuthRefreshToken: The refresh token returned by GetOAuthAccessToken.
• OAuthSettingsLocation: The location where the driver saves the OAuth token values, which persist across connections.

On subsequent data connections, the values for OAuthAccessToken and OAuthRefreshToken are taken from OAuthSettingsLocation, and do not need to be set on the connection.

Manual Refresh of the Azure AD OAuth Access Token

The only value required to manually refresh the Azure AD OAuth access token when connecting to data is the OAuth refresh token.

Use the RefreshOAuthAccessToken stored procedure to manually refresh the OAuthAccessToken after the ExpiresIn parameter value returned by GetOAuthAccessToken has elapsed, then set these connection properties:

• OAuthClientId: The client Id in your application settings.
• OAuthClientSecret: The client secret in your application settings.

Now call RefreshOAuthAccessToken with OAuthRefreshToken set to the OAuth refresh token returned by GetOAuthAccessToken. After the new tokens have been retrieved, open a new connection by setting OAuthAccessToken to the value returned by RefreshOAuthAccessToken.

Finally, store the OAuth refresh token so that you can use it to manually refresh the OAuth access token after it has expired.

Headless Machines

To configure the driver with a user account on a headless machine, you must authenticate on another device that has an internet browser.

You can do this in either of the following ways:

• Obtain the OAuthVerifier value as described below in Option 1: Obtain and Exchange a Verifier Code.
• Install the connector on another machine as described below in Option 2: Transfer OAuth Settings. After you authenticate via the usual browser-based flow, transfer the OAuth authentication values.

Option 1: Obtain and Exchange a Verifier Code

1. Find the authorization endpoint.

   Custom applications only: Set these properties to create the Authorization URL:

   • InitiateOAuth: OFF.
   • OAuthClientId: The client Id assigned when you registered your application.
   • OAuthClientSecret: The client secret assigned when you registered your application.

   Custom and embedded applications: Call the GetOAuthAuthorizationUrl stored procedure.

   1. Open the URL returned by the stored procedure in a browser.
   2. Log in and grant permissions to the connector. You are redirected to the callback URL, which contains the verifier code.
   3. Save the value of the verifier code. You will use this later to set the OAuthVerifier connection property.

2. Exchange the OAuth verifier code for OAuth refresh and access tokens.

   At the headless machine, set these properties:

   • AuthScheme: AzureAD.
   • InitiateOAuth: REFRESH.
   • OAuthVerifier: The verifier code.
   • OAuthSettingsLocation: The location of the file that holds the OAuth token values that persist across connections.

   • Custom applications only:

     • OAuthClientId: The client Id in your custom OAuth application settings.
     • OAuthClientSecret: The client secret in the custom OAuth application settings.

3. After the OAuth settings file is generated, reset the following properties to connect:

   • InitiateOAuth: REFRESH.
   • OAuthSettingsLocation: The location containing the encrypted OAuth authentication values. Make sure this location grants read and write permissions to the connector to enable the automatic refreshing of the access token.

   • Custom applications only:

     • OAuthClientId: The client Id assigned when you registered your application.
     • OAuthClientSecret: The client secret assigned when you registered your application.

Option 2: Transfer OAuth Settings

Before you can connect via a headless machine, you must create and install a connection with the driver on a device that supports an internet browser. Set the connection properties as described above, in Desktop Applications.

After you complete the instructions in Desktop Applications, the resulting authentication values are encrypted and written to the location specified by OAuthSettingsLocation. The default filename is OAuthSettings.txt.

Once you have successfully tested the connection, copy the OAuth settings file to your headless machine.

At the headless machine, set these properties:

• AuthScheme: AzureAD.
• InitiateOAuth: REFRESH.
• OAuthSettingsLocation: The location of your OAuth settings file. Make sure this location gives read and write permissions to the connector to enable the automatic refreshing of the access token.

• Custom applications only:

  • OAuthClientId: The client Id assigned when you registered your application.
  • OAuthClientSecret: The client secret assigned when you registered your application.

Azure Service Principal

Service principals are security objects within an Azure AD application that define what that application can do within a particular Azure AD tenant. Service Principals are created in the Azure service portal. As part of the creation process we also specify whether the service principal will access Azure AD resources via a client secret or a certificate.

Instead of being tied to a particular user, service principal permissions are based on the roles assigned to them. The application access to the resources is controlled through the assigned roles' permissions.

When authenticating using an Azure Service Principal, you must register an application with an Azure AD tenant, as described in Creating an Azure AD Application with Service Principal.

You are ready to connect after setting the properties described in this subsection. These vary, depending on whether you will authenticate via a client secret or a certificate.

Authentication with Client Secret

• AuthScheme: AzureServicePrincipal.
• AzureTenant: The Azure AD tenant to which you wish to connect.
• OAuthGrantType: CLIENT.
• OAuthClientId: The client Id in your application settings.
• OAuthClientSecret: The client secret in your application settings.

Authentication with Certificate

• AuthScheme: AzureServicePrincipalCert.
• AzureTenant: The Azure AD tenant to which you wish to connect.
• OAuthGrantType: CLIENT.
• OAuthClientId: The client Id in your application settings.
• OAuthJWTCert: The JWT Certificate store.
• OAuthJWTCertType: The JWT Certificate store type.