Connecting to Slack

Slack supports authentication via User Token or via the OAuth authentication standard.

User Token Authentication

To authenticate using a non-expiring user token, set AuthScheme to Token and set UserToken to the identification code of the token being used.

OAuth Authentication

Slack provides embedded OAuth credentials that simplify connection from a Desktop application or a Headless machine. To connect from a Web application, you must create a custom OAuth application, as described in Creating a Custom OAuth Application.

To connect via OAuth from all authentication flows, you must set AuthScheme to OAuth.

The following subsections describe how to authenticate to Slack from the available OAuth flows. For information about how to create a custom OAuth application, and why you might want to create one even for auth flows that already have embedded OAuth credentials, see Creating a Custom OAuth Application.

For a complete list of connection string properties available in Slack, see Connection.

Desktop Applications

CData provides an embedded OAuth application that simplifies authentication at the desktop; that is, in situations where the user is using a local server not connected to the internet.

You can also authenticate from the desktop via a custom OAuth application, which you configure and register at the Slack console. For further information, see Creating a Custom OAuth Application.

Before you connect, set these properties:

• InitiateOAuth: GETANDREFRESH. Used to automatically get and refresh the OAuthAccessToken.
• Custom OAuth 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 defined when you registered your custom OAuth application.

When you connect, the provider opens Slack's OAuth endpoint in your default browser. Log in and grant permissions to the application.

After you grant permissions to the application, the provider completes the OAuth process:

1. The provider obtains an access token from Slack 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 it automatically.

Web Applications

Authenticating via the Web requires that you create and register a custom OAuth application with Slack, as described in Creating a Custom OAuth Application. You can then use the provider to get and manage the OAuth token values.

This section describes how to get the OAuth access token, how to have the driver refresh the OAuth access token automatically, and how to refresh the OAuth access token manually.

Get the OAuth access token:

1. To obtain the OAuthAccessToken, set these connection properties:
   • OAuthClientId: The client Id in your custom OAuth application settings.
   • OAuthClientSecret: The client secret in your custom OAuth application settings.

2. Call stored procedures to complete the OAuth exchange:
   • Call the GetOAuthAuthorizationURL stored procedure. Set the AuthMode input to WEB and the CallbackURL to the Redirect URI you specified in your custom OAuth 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 and authorize the web application. You are redirected back to the callback URL.
   • 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:

To have the provider automatically refresh the OAuth access token, do the following:

1. The first time you connect to data, set these connection parameters:
   • InitiateOAuth: REFRESH.
   • OAuthClientId: The client Id in your custom OAuth application settings.
   • OAuthClientSecret: The client secret in your custom OAuth application settings.
   • OAuthAccessToken: The access token returned by GetOAuthAccessToken.
   • OAuthSettingsLocation: The path where you want the provider to save the OAuth values, which persist across connections.
2. On subsequent data connections, set:
   • InitiateOAuth
   • OAuthSettingsLocation

Manual refresh of the OAuth access token:

The only value needed to manually refresh the OAUth access token is the OAuth refresh token.

1. To manually refresh the OAuthAccessToken after the ExpiresIn period (returned by GetOAuthAccessToken) has elapsed, call the RefreshOAuthAccessToken stored procedure.
2. Set these connection properties:
   • OAuthClientId: The Client Id in your custom OAuth application settings.
   • OAuthClientSecret: The Client Secret in your custom OAuth application settings.

3. Call RefreshOAuthAccessToken with OAuthRefreshToken set to the OAuth refresh token returned by GetOAuthAccessToken.
4. After the new tokens have been retrieved, set the OAuthAccessToken property to the value returned by RefreshOAuthAccessToken. This opens a new connection.

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

Headless Machines

If you need to log in to a resource that resides 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.
• 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.

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 as follows:

1. Authenticate from the machine with an internet browser, and obtain the OAuthVerifier connection property.

   If you are using the embedded OAuth application, call the GetOAuthAuthorizationURL stored procedure. Open the URL returned by the stored procedure in a browser.

   If you are using a custom OAuth application, set these properties:

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

2. Call the GetOAuthAuthorizationURL stored procedure. The stored procedure returns the CallbackURL established when the custom OAuth application was registered. (See Creating a Custom OAuth Application.)

   Copy this URL and paste it into a new browser tab.

3. Log in and grant permissions to the provider. The OAuth application redirects you the redirect URI, with a parameter called code appended. Note the value of this parameter; you will need it later, to configure the OAuthVerifier connection property.

4. Exchange the OAuth verifier code for OAuth refresh and access tokens. On the headless machine, to obtain the OAuthAccessToken, set these connection properties:

   • InitiateOAuth: REFRESH.
   • OAuthVerifier: The noted verifier code (the value of the code parameter in the redirect URI).
   • OAuthSettingsLocation: persist the encrypted OAuth authentication values to the specified file.
   • Custom OAuth applications only:
     • OAuthClientId: The client Id in your custom OAuth application settings.
     • OAuthClientSecret: The client secret in the custom OAuth application settings.

5. Test the connection to generate the OAuth settings file.

6. You are ready to connect after you re-set these properties:

   • InitiateOAuth: REFRESH.
   • OAuthSettingsLocation: The file containing the encrypted OAuth authentication values. To enable the automatic refreshing of the access token, be sure that this file gives read and write permissions to the provider.
   • Custom OAuth applications only:
     • OAuthClientId: The client Id assigned when you registered your application.
     • OAuthClientSecret: The client secret assigned when you registered your application.

Option 2: Transferring OAuth Settings

Prior to 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 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 these connection properties:

• InitiateOAuth: REFRESH
• 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.
• Custom OAuth 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.