How to properly refresh your OAuth2 access token in DFP API

In July we announced that starting in August 2016, all versions of the DFP API would return HTTP 401 errors instead of SOAP AUTHENTICATION_FAILED errors. We have learned that some developers have been relying on catching an AUTHENTICATION_FAILED error to know when to refresh an access token. This is not the recommended way to determine when your access token needs refreshing and is not supported.

The change described above will break code that relies on catching an AUTHENTICATION_FAILED error. We have temporarily rolled back the change to give developers who haven’t migrated more time to update their code and will roll this change out again on November 30, 2016 and ask that you update your code before then.

Note: If you’re taking advantage of our client libraries, no change is required; our client libraries handle refreshing an access token with our recommended approach.

Instead of relying on an AUTHENTICATION_FAILED error, the recommended way is to calculate how soon the access token is going to expire before making an API call, and refresh it if it’s about to expire soon.

  • Whenever you obtain a new access token, calculate the token’s expiration time by adding the expires_in time returned with the access token to the current time.
    • For example, if you received an access token on Oct 21, 16:05 EDT and the access token lasts for 3600 seconds, the token would expire on Oct 21, 17:05 EDT.
  • Then, before every DFP API call, check when the access token will expire before using it: if it is going to expire within a certain time window (say, in the next 60 seconds), you should refresh it before making the API call.
    • To calculate this, subtract the current time from the token’s expiration time that you calculated above.
You can see an example of how this is done in our Java client library and use it as a reference to help you implement the above.

As always, if you have any questions, feel free to drop us a line on the DFP API forums or the Ads Developer Google+ page.
 - , DFP API Team