Connecting to SAP Gateway

SAP Gateway provides two ways to connect to data:

• To connect to your own local data via the desktop (non-browser connection, referred to below as "basic authentication"), use the CData-supplied embedded OAuth application.
• To connect to shared data over the network (browser connection), use a custom OAuth application.

To access SAP Gateway tables, set the following connection properties:

• Url = the URL of your environment, or the full URL of the service. For example, the full URL might appear as: https://sapes5.sapdevcenter.com/sap/opu/odata/IWBEP/GWSAMPLE_BASIC/. In this example, the environment url would just be: https://sapes5.sapdevcenter.com. Add any additional properties using the CustomUrlParams property.
• Namespace = the appropriate Service Namespace. In the example above, IWBEP is the namespace. It is optional if the full url to the service is specified.
• SAP Gateway = the service from which you want to retrieve data. In the example above, the service is GWSAMPLE_BASIC. It is not required if the full url is specified.
• CustomUrlParams = any required additional properties that need to be included with the HTTP request; for example, sap-client=001&sap-language=EN.

Authenticating to SAP Gateway

SAP Gateway allows both basic and OAuth 2.0 authentication. Use basic authentication to connect to your own account, or use OAuth to authenticate to shared data via a browser connection.

Basic

To enable basic authentication, set the following properties:

• AuthScheme = Basic.
• User = the username you use to log in to SAP Gateway.
• Password = the password you use to log in to SAP Gateway.

After you set the above properties are set, you are ready to connect. Use your personal credentials to access your local data.

OAuth

The following subsections provide details about authenticating from a desktop application, the web, or a headless machine. For information about creating a custom OAuth application, see Creating a Custom OAuth Application.

Desktop Applications

To authenticate with the credentials for a custom OAuth application, you must get and refresh the OAuth access token. After you do that, you are ready to connect.

Get and Refresh the OAuth Access Token

• OAuthClientId = the client Id assigned when you registered your application.
• OAuthClientSecret = the client secret that was assigned when you registered your application.
• CallbackURL = the redirect URI that was defined when you registered your application.

When you connect, the provider opens SAP Gateway's OAuth endpoint in your default browser.

Log in and grant permissions to the application. The provider then completes the OAuth process:

1. The provider obtains an access token from SAP Gateway and uses it to request data.
2. The OAuth values are saved in the path specified in OAuthSettingsLocation. These values persist across connections.

When the access token expires, the provider refreshes the access token automatically.

Web Applications

To authenticate from the web with the credentials for a custom OAuth application, you must register a custom OAuth application with SAP Gateway. You can then use the provider to get and manage the OAuth token values.

Get an OAuth Access Token

To obtain the OAuthAccessToken set the following connection properties:

• OAuthClientId = the client Id in your application settings.
• OAuthClientSecret = the client secret in your application settings.

To complete the OAuth exchange, call stored procedures as follows:

1. Call the GetOAuthAuthorizationURL stored procedure. Set the AuthMode input to WEB and the CallbackURL to the Redirect URI you specified in your application settings. The stored procedure returns the URL to the OAuth endpoint.
2. Navigate to the URL that the stored procedure returned in Step 1. Log in and authorize the web 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 redirect URI.

After you obtain the access and refresh tokens, you can connect to data and refresh the OAuth access token automatically.

Automatic Refresh of the OAuth Access Token

If you want the provider to refresh the OAuth access token automatically, do the following.

The first time you connect to data, set the following connection parameters:

• 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.
• OAuthSettingsLocation = the path where you want the provider to save OAuth values that persist across connections.

On subsequent data connections, set the following connection parameters:

• InitiateOAuth
• OAuthSettingsLocation

Headless Machines

If you need to authenticate via OAuth 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:

• Option 1: Obtain the OAuthVerifier value as described in "Obtain and Exchange a Verifier Code" below.
• Option 2: Install the provider 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.

After you execute either Option 1 or Option 2, configure the driver to automatically refresh the access token on the headless machine.

Option 1: Obtaining and Exchanging a Verifier Code

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

1. Set the following properties:
   • InitiateOAuth = OFF.
   • OAuthClientId = the client Id assigned when you registered your application.
   • OAuthClientSecret = the client secret assigned when you registered your application.
2. Use the appropriate CalllbackURL to call the GetOAuthAuthorizationURL stored procedure.
3. Copy the returned URL into a browser and open the page.
4. Log in and grant permissions to the provider. You are redirected to the redirect URI.
5. Record the code parameter that is appended to the redirect URI. You will use it later, when you set up the OAuthVerifier connection property.
6. To exchange the OAuth verifier code for OAuth refresh and access tokens, set the following connection properties, which provide the OAuth authentication values:
   • InitiateOAuth = REFRESH.
   • OAuthVerifier = the noted verifier code (the value of the code parameter in the redirect URI).
   • OAuthClientId = the client Id in your custom OAuth application settings.
   • OAuthClientSecret = the client secret in the custom OAuth application settings.
   • OAuthSettingsLocation = persist the encrypted OAuth authentication values to the specified file.
7. Test the connection to generate the OAuth settings file, then re-set the following properties to connect:
   • InitiateOAuth = REFRESH.
   • OAuthClientId = the client Id assigned when you registered your application.
   • OAuthClientSecret = the client secret assigned when you registered your application.
   • OAuthSettingsLocation = the file containing the encrypted OAuth authentication values. Make sure this file gives read and write permissions to the provider to enable the automatic refreshing of the access token.

Option 2: Transfer OAuth Settings

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

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".

Test the connection to generate the OAuth settings file, then copy the OAuth settings file to your headless machine.

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

• InitiateOAuth = REFRESH.
• OAuthClientId = the client Id assigned when you registered your application.
• OAuthClientSecret = the client secret assigned when you registered your application.
• OAuthSettingsLocation = the path to the OAuth settings file you copied from the machine with the browser. To enable automatic refreshing of the access token, ensure that this file gives read and write permissions to the provider.