Establishing a Connection

Creating a JDBC Data Source

You can create a JDBC data source to connect from your Java application. Creating a JDBC data source based on the CData JDBC Driver for Gmail consists of three basic steps:

Add the driver JAR file to the classpath. The JAR file is located in the lib subfolder of the installation directory. Note that the .lic file must be located in the same folder as the JAR file.
Provide the driver class. For example:
```
cdata.jdbc.gmail.GmailDriver
```
Provide the JDBC URL. For example:
```
jdbc:gmail:user=myuseraccount;password=mypassword;

or

jdbc:cdata:gmail:user=myuseraccount;password=mypassword;
```
The second format above can be used whenever there is a conflict in your application between drivers using the same URL format to ensure you are using the CData driver. The URL must start with either "jdbc:gmail:" or "jdbc:cdata:gmail:" and can include any of the connection properties in name-value pairs separated with semicolons.

Connecting to Gmail

The driver supports connecting to Gmail using the modern REST API and the IMAP protocol. Control how to connect by using AuthScheme. The REST API is the default.

Authenticating to Gmail

Available authentication schemes include:

Basic (IMAP only)
OAuth
OAuthJWT
GCP Instance Accounts

Basic (IMAP only)

If you plan to use IMAP, you need to enable it so the driver can communicate with Gmail through the IMAP protocol. IMAP enables all your client devices to work with the same, remote data, instead of individual copies. Follow the steps below to enable access to Gmail over IMAP:

Open the Gmail Web interface and click the Settings button (the icon is a gear).
On the Forwarding and POP/IMAP tab, select Enable IMAP.
Save your changes.

Deprecation notice: As of May 30, 2022, Google no longer supports the use of third-party apps or devices that ask you to sign into your Google Account using only your username and password. There are alternatives that still allow you to use this authentication method, for example, App Passwords. Considering this, the Basic AuthScheme is marked as deprecated. We recommend switching to OAuth because it is a more secure method of authentication.

Set the AuthScheme to Basic and Schema to IMAP for this authentication method. This approach is suitable if you need to access your own data. Set the User and Password properties to valid Gmail user credentials.

User Accounts (OAuth)

AuthScheme must be set to OAuth in all user account flows. In addition, all user account flows require that you create and register a custom OAuth application with Gmail. You can then use the driver to acquire and manage the OAuth token values. See Creating a Custom OAuth App for more information about custom applications.

NOTE: CData supports both IMAP and REST schema for OAuth authentication. The only difference is the IMAP requires the User connection property. REST does not.

Desktop Applications

After setting the following connection properties, you are ready to connect:

InitiateOAuth: Set this to GETANDREFRESH, which instructs the driver to automatically attempt to get and refresh the OAuth access token.
OAuthClientId: Set this to the Client Id in your custom OAuth application settings.
OAuthClientSecret: Set this to the Client Secret in the custom OAuth application settings.
User: (IMAP only) Set this to the Gmail user account used to authenticate.

When you connect the driver opens the OAuth endpoint in your default browser. Log in and grant permissions to the application. The driver then completes the OAuth process as follows:

Extracts the access token from the callback URL.
Obtains a new access token when the old one expires.
Saves OAuth values in OAuthSettingsLocation. These values persist across connections.

Web Applications

Get an OAuth Access Token

Set the following connection properties to obtain the OAuthAccessToken:

OAuthClientId: Set this to the Client Id in your application settings.
OAuthClientSecret: Set this to the Client Secret in your application settings.
User: (IMAP only) Set this to the Gmail user account used to authenticate.

Then call stored procedures to complete the OAuth exchange:

Call the GetOAuthAuthorizationURL stored procedure. Set the CallbackURL input to the Callback URL you specified in your application settings. The stored procedure returns the URL to the OAuth endpoint.
Navigate to the URL that the stored procedure returned in Step 1. Log in to the custom OAuth application and authorize the web application. Once authenticated, the browser redirects you to the callback URL.
Call the GetOAuthAccessToken stored procedure. Set AuthMode to WEB and the Verifier input to the "code" parameter in the query string of the callback URL.

After you have obtained the access and refresh tokens, you can connect to data and refresh the OAuth access token either automatically or manually.

Automatic Refresh of the OAuth Access Token

To have the driver automatically refresh the OAuth access token, set the following on the first data connection:

InitiateOAuth: Set this to REFRESH.
OAuthClientId: Set this to the client Id in your application settings.
OAuthClientSecret: Set this to the client secret in your application settings.
OAuthAccessToken: Set this to the access token returned by GetOAuthAccessToken.
OAuthRefreshToken: Set this to the refresh token returned by GetOAuthAccessToken.
OAuthSettingsLocation: Set this to the path where the driver saves the OAuth token values, which persist across connections.
User: (IMAP only) Set this to the Gmail user account used to authenticate.

On subsequent data connections, the values for OAuthAccessToken and OAuthRefreshToken are taken from OAuthSettingsLocation.

Manual Refresh of the OAuth Access Token

The only value needed to manually refresh the 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 the following connection properties:

OAuthClientId: Set this to the Client Id in your application settings.
OAuthClientSecret: Set this to the Client Secret in your application settings.
User: (IMAP only) Set this to the Gmail user account used to authenticate.

Then 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 the OAuthAccessToken property 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 to use OAuth with a user account on a headless machine, you need to authenticate on another device that has an internet browser.

Choose one of two options:
- Option 1: Obtain the OAuthVerifier value as described in "Obtain and Exchange a Verifier Code" below.
- Option 2: Install the driver on a machine with an internet browser and transfer the OAuth authentication values after you authenticate through the usual browser-based flow, as described in "Transfer OAuth Settings" below.
Then configure the driver to automatically refresh the access token on the headless machine.

Option 1: Obtain and Exchange a Verifier Code

To obtain a verifier code, you must authenticate at the OAuth authorization URL.

Follow the steps below to authenticate from the machine with an internet browser and obtain the OAuthVerifier connection property.

Create the Authorization URL by setting the following properties:
- InitiateOAuth: Set to OFF.
- OAuthClientId: Set to the client Id assigned when you registered your application.
- OAuthClientSecret: Set to the client secret assigned when you registered your application.
- User: (IMAP only) Set this to the Gmail user account used to authenticate.
Call the GetOAuthAuthorizationURL stored procedure with the appropriate CallbackURL. Open the URL returned by the stored procedure in a browser.
Log in and grant permissions to the driver. You are then redirected to the callback URL, which contains the verifier code.
Save the value of the verifier code. Later you will set this in the OAuthVerifier connection property.

Next, you need to exchange the OAuth verifier code for OAuth refresh and access tokens. Set the following properties:

On the headless machine, set the following connection properties to obtain the OAuth authentication values:

InitiateOAuth: Set this to REFRESH.
OAuthVerifier: Set this to the verifier code.
OAuthClientId: Set this to the Client Id in your custom OAuth application settings.
OAuthClientSecret: Set this to the Client Secret in the custom OAuth application settings.
OAuthSettingsLocation: Set this to persist the encrypted OAuth authentication values to the specified file.
User: (IMAP only) Set this to the Gmail user account used to authenticate.

After the OAuth settings file is generated, you need to re-set the following properties to connect:

InitiateOAuth: Set this to REFRESH.
OAuthClientId: Set this to the client Id assigned when you registered your application.
OAuthClientSecret: Set this to the client secret assigned when you registered your application.
OAuthSettingsLocation: Set this to the file containing the encrypted OAuth authentication values. Make sure this file gives read and write permissions to the driver to enable the automatic refreshing of the access token.

Option 2: Transfer OAuth Settings

Prior to connecting on a headless machine, you need to create and install a connection with the driver on a device that supports an internet browser. Set the connection properties as described in "Desktop Applications" above.

After completing the instructions in "Desktop Applications", the resulting authentication values are encrypted and written to the path 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.

On the headless machine, set the following connection properties to connect to data:

InitiateOAuth: Set this to REFRESH.
OAuthClientId: Set this to the client Id assigned when you registered your application.
OAuthClientSecret: Set this to the client secret assigned when you registered your application.
OAuthSettingsLocation: Set this to the path to your OAuth settings file. Make sure this file gives read and write permissions to the driver to enable the automatic refreshing of the access token.
User: (IMAP only) Set this to the Gmail user account used to authenticate.

Service Accounts (OAuthJWT)

To authenticate using a service account, you must create a new service account and have a copy of the accounts certificate. If you do not already have a service account, you can create one by following the procedure in Creating a Custom OAuth App. NOTE: The OAuth JWT authentication method requires delegation. This is only possible if you are using a Google Workspace account.

For a JSON file, set these properties:

AuthScheme: Set this to OAuthJWT.
InitiateOAuth: Set this to GETANDREFRESH.
OAuthJWTCertType: Set this to GOOGLEJSON.
OAuthJWTCert: Set this to the path to the .json file provided by Google.
OAuthJWTSubject: (optional) Only set this value if the service account is part of a GSuite domain and you want to enable domain-wide delegation. The value of this property should be the email address of the user whose data you want to access. See the Google Workshop Admin help for information about implementing domain-wide delegation.

For a PFX file, set these properties:

AuthScheme: Set this to OAuthJWT.
InitiateOAuth: Set this to GETANDREFRESH.
OAuthJWTCertType: Set this to PFXFILE.
OAuthJWTCert: Set this to the path to the .pfx file provided by Google.
OAuthJWTCertPassword: (optional) Set this to the .pfx file password. In most cases you must provide this since Google encrypts PFX certificates.
OAuthJWTCertSubject: (optional) Set this only if you are using a OAuthJWTCertType which stores multiple certificates. This should not be set for PFX certificates generated by Google.
OAuthJWTIssuer: Set this to the email address of the service account. This address will usually include the domain iam.gserviceaccount.com.
OAuthJWTSubject: (optional) Only set this value if the service account is part of a GSuite domain and you want to enable domain-wide delegation. The value of this property should be the email address of the user whose data you want to access. See the Google Workshop Admin help for information about implementing domain-wide delegation.
User: Set this to the user of the Gmail account you are connecting to.

GCP Instance Accounts

When running on a GCP virtual machine, the driver can authenticate using a service account tied to the virtual machine. To use this mode, set AuthScheme to GCPInstanceAccount.