For example, if you have infrastructure limitations in facilitating more than a certain number of requests to an API at a time, set throttling tiers to the APIs to limit access to it accordingly. Each tier defines a maximum number of requests per minute. The API Manager comes with three default tiers as Gold, Silver and Bronze.
API-level throttling tiers are defined by the API creator when creating an API using the API Publisher. At subscription time, the consumers of the API can select which tier they are interested in using the API Store as follows:
According to the tiers s/he selects, the subscriber is granted a maximum number of requests to the API.
With capability to define throttling at three levels, the final request limit granted to a given user on a given API is ultimately defined by the summed output of all of these different throttling tiers together. For example, lets say two users subscribe to an API using the Gold subscription, which allows 20 requests per minute. They both use the application App1 for this subscription, which again has a throttling tier set as 20 requests per minute. All resource level throttling tiers are unlimited. In this scenario, although both users are eligible for 20 requests per minute access to the API, each ideally has a limit of only 10 requests per minute. This is due to the application-level limitation of 20 requests per minute.