Connecting to Facebook

Before you can connect to Facebook, you must obtain the appropriate connection properties. Since Facebook supports user authentication only via OAuth, you must either use the CData-supplied embedded OAuth application or create a custom OAuth application, as described in Creating a Custom OAuth Application.

You can also set the following optional connection properties:

• Target: This property enables you to filter the results of all queries in the connection to records that match a specified target. For example, to retrieve comments on a video, specify the Id of the video as the target. To specify this restriction per query, use the table's Target column.
• AggregateFormat: This property enables you to return aggregate columns as XML data rather than JSON (the default format).

Authenticating to Facebook

The following subsections describe how to authenticate to Facebook from any available OAuth access flow. For information about creating a custom OAuth application, see Creating a Custom OAuth Application.

Desktop Applications

CData provides an embedded OAuth application that simplifies OAuth desktop Authentication. You can also create a custom OAuth application, as described in Creating a Custom OAuth Application.

For authentication, the only difference between the two methods is that to connect via a custom OAuth application you must set the following connection properties:

• InitiateOAuth: Set to GETANDREFRESH. You can use InitiateOAuth to avoid repeating the OAuth exchange and manually setting the OAuthAccessToken.
• OAuthClientId: (custom applications only) Set to the client Id in your application settings.
• OAuthClientSecret: (custom applications only) Set to the client secret in your application settings.
• CallbackURL: Set to the Redirect URL in your application settings.
• Scope (optional): Set this only if you need to customizie the permissions that the driver requests.
• AuthenticateAsPage (optional): Set this to a page name or Id to make requests as a page. The page must be managed by the authenticated user.

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

1. Extracts the access token from the callback URL;
2. obtains a new access token when the old one expires; and
3. saves OAuth values in OAuthSettingsLocation. These values persist across connections.

Web Applications

When connecting via a Web application, you must create and register a custom OAuth application with Facebook, as described in Creating a Custom OAuth Application. You can then use the adapter to get and manage the OAuth token values.

Get an OAuth Access Token

To obtain the OAuthAccessToken set the following connection properties:

• OAuthClientId: Set to the client Id in your application settings.
• OAuthClientSecret: Set to the client secret in your application settings
• Scope (optional): Set only if you need to customizie the permissions that the driver requests.
• AuthenticateAsPage (optional): Set to a page name or Id to make requests as a page. The page must be managed by the authenticated user.

Now 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 app settings. If necessary, set the "Scope" parameter to request custom permissions.
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 "Scope" parameter to request custom permissions.

To connect to data, set the OAuthAccessToken connection property to the access token returned by the stored procedure. When the access token expires after ExpiresIn seconds, call GetOAuthAccessToken again to obtain a new access token.

Headless Machines

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

Creating a custom OAuth app is optional in the headless OAuth flow; if you want to skip creating an app, you can connect with the driver's embedded OAuth credentials. However, you might want to create a custom OAuth app to change the information displayed when users log into Facebook to grant permissions to the driver. For information on how to create a custom OAuth application, see Creating a Custom OAuth Application.

1. Choose one of these two options:
   • Option 1: Obtain the OAuthVerifier value as described in "Obtain and Exchange a Verifier Code", below.
   • Option 2: Install the adapter on another machine and transfer the OAuth authentication values after you authenticate through the usual browser-based flow, as described in "Transfer OAuth Settings", below.
2. Configure the adapter to automatically refresh the access token from 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.

1. If you are using the Embedded OAuth Application:
   1. Call the GetOAuthAuthorizationURL stored procedure.
   2. Click Facebook OAuth endpoint to open the endpoint in your browser.
2. If you are using a custom OAuth application, 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.
3. Call the GetOAuthAuthorizationURL stored procedure with the CallbackURI input parameter set to the exact Redirect URI you specified in your application settings.
4. Open the URL returned by the stored procedure in a browser.
5. Log in and grant permissions to the adapter. You are then redirected to the callback URL, which contains the verifier code.
6. Save the value of the verifier code. Later you will set this in the OAuthVerifier connection property.

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

• OAuthClientId: Set to the Client ID in your OAuth Integration settings.
• OAuthClientSecret: Set to the Client Secret in your OAuth Integration settings.
• OAuthVerifier: Set to the verifier code.
• OAuthSettingsLocation: Set to persist the encrypted OAuth authentication values to the specified location.
• InitiateOAuth: Set to REFRESH.

Connect to Data

After the OAuth settings file is generated, set the following properties to connect to data:

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

Option 2: Transfer OAuth Settings

To install the adapter on another machine, authenticate, and then transfer the resulting OAuth values:

1. On a second machine, install the adapter and connect with the following properties set:
   • OAuthSettingsLocation: Set to a writable location.
   • InitiateOAuth: Set to GETANDREFRESH.
   • OAuthClientId: Set to the client ID in your app settings.
   • OAuthClientSecret: Set to the client secret in your app settings.
   • CallbackURL: Set to the callback URL in your app settings.
2. Test the connection to authenticate. The resulting authentication values are written and encrypted to the path specified by OAuthSettingsLocation. After 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 to REFRESH.
   • OAuthSettingsLocation: Set to the location of your OAuth settings file. Make sure this location gives read and write permissions to the adapter to enable the automatic refreshing of the access token.

Requesting Additional Permissions

You may find while using the adapter that Facebook returns an error stating your app does not have permissions to do a certain action. To resolve this, you must generate a new OAuth access token with the required permissions. Set the Scope property in the authentication step for a desktop application.

Web applications need to call the GetOAuthAuthorizationURL and GetOAuthAccessToken stored procedures, which have inputs for the permissions you would like to request.

Note that these are comma-separated lists of permissions, so you can request more than one per authorization request. You can find a list of available Facebook permissions here:

http://developers.facebook.com/docs/authentication/permissions/

Permissions that may be required depending on your use case are:

user_birthday, user_photos, user_videos, user_likes, user_hometown, user_location, read_insights, pages_manage_metadata, pages_read_engagement, pages_read_user_content, pages_messaging, business_management, instagram_basic, instagram_manage_insights

Note that in some cases, permissions restrictions might not be due to missing but requestable Facebook OAuth permissions, but instead might be due to missing OAuth app features, like Page Public Content Access or Page Public Metadata Access. These features are tied to the OAuth app as a whole, and cannot be approved or denied for individual OAuth access tokens requested by users. Consider Creating a Custom OAuth Application if you need access to app features not available with the embedded OAuth app.

AuthenticateAsPage Property

Use the AuthenticateAsPage connection property if you want to post as a single page. To query collections of pages, leave AuthenticateAsPage blank, in which case CData tools automatically detect which page tokens to use.

The following sections compare the two options.

Posting as a Page

After authenticating to Facebook with your user account, you can post, etc. as one of the pages you manage: Set the AuthenticateAsPage property to the Id of the page you want. You can find the Ids for all pages your account has access to by querying the Pages view.

Automatic Page

Facebook has made a number of recent changes that require page tokens for most resources owned by a page. This can be troublesome if you manage multiple pages and want to execute the same queries across all pages (such as retrieving Insights). In order to make this work seamlessly with our tools, we have added a way to automatically detect the page token to use. For this to work, simply do not specify the AuthenticateAsPage. Note that the correct page token can only be resolved if the page id is specified as part of the target in the request. This means for some requests you will still need to manually specify AuthenticateAsPage.