1. A content manager that fills requests for requested content by accessing repositories storing the requested content when the repositories may not be compatible with one or more requesting systems, the content manager comprising: a request for content stored in a repository employing a protocol inaccessible to an originator of the request; a metadata registry including metadata describing the requested content stored in the repository, where the metadata includes an identification of a particular external service capable of communicating with the repository using the protocol to acquire the requested content; and an external service registry listing the particular external service among a plurality of external services, wherein the external service registry associates information for interacting with the protocol for the particular external service, and for each of the other external services, associates information for interacting with appropriate protocols for that other external service.