Web API needing a token grant

Web APIs that follow the OAuth pattern need special treatment.

Besides needing a client id and client secret, API calls that do actual work require a bearer token, which is generated by a special call to the API.

So, using such an API is a two step process:

1. Given the client id and secret, request a token
2. Supplying the token, make the API call that does actual work

While one could do the two steps for each actual API call, it is better practice to store the token from the first call in an entity variable and then use it in each API call that does actual work.