1. A system for providing an application programming interface (API) manager for use with a service bus runtime, comprising: a computer including one or more microprocessors; a service bus runtime, executing on the computer, that includes a plurality of proxy services; an API catalog that is automatically synchronized with the service bus runtime, and that includes an API entry for each of the plurality of proxy services, wherein one or more API entries are published, and available to be subscribed to by one or more applications associated with an API consumer; and an API managing component that monitors each API subscription based on information passed from the service bus runtime, generates API usage metrics for each API subscription, and displays the usage metrics at the API portal.