This API retrieves campaign or asset information from the catalog. You will need to know the specific item that you require, e.g. you want details about a specific campaign for which you know the tag. Another example is you want to get details of a specific asset for which you know the unique key assigned to the asset.
The API is designed so that end-users are not able to discover information about the catalog, for example searching is not allowed. This allows for the public key to be set in the HTML pages that are delivered to the end-user and why it is called the Public Key API.
This API is designed for high-volume web facing queries to the catalog.
If you need programmatic access to the catalog to update, view or edit, you will need an OAuth token. This will give you your user level access to the catalog via API.