OAuth Connector (Custom OAuth 2.0)

Authenticate at arbitrary OAuth 2.0 (RFC5849) APIs using the “Authorization Code” flow. The target group of this node are intermediate users with an understanding of OAuth fundamentals and developers. From a high-level perspective, this works as follows:

1. Register an “application” at the service with which you want to authenticate (the steps for this depend on the actual service – have a look at the developer API documentation). If you’re asked for a “Callback URL”, enter “http://localhost:55931” (or if you want to use a different port than the default, just update the node configuration accordingly). After completing this step, you should get a personal “API Key” and “API Secret” (the exact terminology might vary).
2. Open the configuration of this node, and enter the API Key and Secret which you received in the previous step into the corresponding fields. Also configure the URL inputs according to the service’s instructions.
3. Click the Authorize button. A browser window will open and (unless you’re already logged into the service) ask for login credentials and permission to access the service. Once you have authenticated successfully, you will see an “Access granted” page in your browser which you can close and go back to KNIME.
4. The dialog will show “Successfully received an access token”. Close the dialog and execute the node. The table which is created on node execution will contain the access token (and probably other information such as a refresh token, scope, and expiration info). For your convenience, this information is also available as Flow Variables. If the service also returned a refresh token, the node will request a new access token when it is re-executed.
5. Use the obtained access token and supply it to your nodes which access the REST API – we strongly recommend the rock-solid, battle-proof HTTP Retriever from Palladian. But other nodes, such as KNIME’s integrated REST client also work. Usually the token will be provided in an “Authorization” header, but this depends on the actual service – please refer to the documentation of the API you’re trying to access.

Note: Also have a look at the node “OAuth Connector” which includes 50+ predefined, ready-to-use services.