This namespace is provided for common code needed by the roles and
permissions namespaces.

[...
 ["my/route" {
  :get {:handler my-handlers/my-route
        :permissions #{:read}}
  :post ...}]
 ...]

Permissions for CMR OPeNDAP are utilized in the application routes when it is
necessary to limit access to resources based on the specific capabilities
granted to a user.

Permissions are included in the route definition along with the route's
handler. For example:
```
[...
 ["my/route" {
  :get {:handler my-handlers/my-route
        :permissions #{:read}}
  :post ...}]
 ...]

[...
 ["my/route" {
  :get {:handler my-handlers/my-route
        :roles #{:admin}}
  :post ...}]
 ...]

Roles for CMR OPeNDAP are utilized in the application routes when it is
necessary to limit access to resources based on the role of a user.

Roles are included in the route definition along with the route's handler.
For example:
```
[...
 ["my/route" {
  :get {:handler my-handlers/my-route
        :roles #{:admin}}
  :post ...}]
 ...]

The functions in this API are responsible for such things as making queries
to CMR Access Control to get token-to-user mappings, extracting tokens from
request headers, and defining caching keys and related tasks.