The preceding configuration assumed that the same Basecamp login would be used for all users in the org. This may be acceptable for some integrations; however, given that Basecamp is a project management solution, it's best to ensure that any updates are made by distinct users. 

To ensure this is the case, each user must have a user in the Salesforce org as well as in Basecamp. By setting the Identity Type to Per User rather than Named Principle, Salesforce exposes the ability for administrators and/or each user to authenticate themselves with their own Basecamp account through the My Personal Setting menu accessed from the user's avatar. The following screenshot shows a Salesforce user being associated with a Named Credential:

So far, we have configured an external service via Named Credentials and made an external callout via Apex. In the next section, we will review the ability to do this without code, so long as the service has been described according to a specific industry standard.