ADO.NET Provider for Microsoft Exchange

Build 24.0.9175

Establishing a Connection

Connecting to Microsoft Exchange

There are two schemas available for connecting to Exchange:

  • Exchange Web Services (EWS), which is no longer being updated but is still available for both Exchange OnPremise and Exchange Online.
    Note: Microsoft recommends that Exchange Online users switch to Microsoft Graph.
  • Microsoft Graph

For a look at the data model for each of these schemas, see "Data Model".

To switch between EWS and Microsoft Graph, set Schema to either EWS or MSGraph.

Exchange Online users who still want to use EWS should set Schema to EWS and the Platform to Exchange_Online.

Authenticating to Microsoft Exchange OnPremises

Microsoft Exchange OnPremises supports Basic (default), Digest, Negotiate, or NTLM authentication.

Basic (default)

Microsoft Exchange OnPremises defaults sets Basic as the default authentication. To support Basic authentication, set these properties:

Digest

To support HTTP Digest authentication in an On-Premises deployment, set these properties:

Negotiate

Negotiate is used to direct the driver to negotiate an authentication mechanism with the server. The purpose of this authscheme is to facilitate Kerberos authentication in an On-Premises deployment. To support Kerberos authentication in an On-Premises deployment, set these properties:

NTLM

To use Windows NT LAN Manager (NTLM) authentication in an On-Premises deployment, set these parameters:

Authenticating to Microsoft Exchange Online

Microsoft Exchange Online supports several types of OAuth-based authentication.

If you are connecting to Exchange Online platform through EWS, set AuthScheme to AzureAD, AzureServicePrincipal, or AzureMSI.

If you connect to Exchange Online through Microsoft Graph, set Schema to MSGraph. When Schema is set to MSGraph, the Platform is ignored.

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 about creating a custom OAuth application, see Creating an Azure AD Application.

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 an Azure AD Application.) 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 provider opens Microsoft Exchange's OAuth endpoint in your default browser. Log in and grant permissions to the application.

The provider completes the OAuth process, obtaining an access token from Microsoft Exchange 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 provider refreshes it automatically.

Web Applications

To authenticate via Azure AD using a Web application, you must register a custom OAuth application with Microsoft Exchange (see Creating an Azure AD Application). You can then use the provider to get and manage the OAuth token values.

Get an Azure AD OAuth Access Token

First, set these connection properties to obtain the OAuthAccessToken:

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

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:

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 provider 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:

    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 provider. 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:

  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 provider 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 provider 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

Azure Service Principal is role-based application-based authentication. This means that authentication is done per application, rather than per user. All tasks taken on by the application are executed without a default user context, but based on the assigned roles. The application access to the resources is controlled through the assigned roles' permissions.

For information about how to set up Azure Service Principal authentication, see Creating an Azure AD App with Service Principal.

Managed Service Identity (MSI)

If you are running Microsoft Exchange on an Azure VM and want to automatically obtain Managed Service Identity (MSI) credentials to connect, set AuthScheme to AzureMSI.

User-Managed Identities

To obtain a token for a managed identity, use the OAuthClientId property to specify the managed identity's client_id.

If your VM has multiple user-assigned managed identities, you must also specify OAuthClientId.

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Build 24.0.9175