1. A non-transitory computer readable medium including program code for providing a message-based interface for exchanging information about user feed administrator objects that monitor and push feeds to a user, the medium comprising: program code for receiving a first message via a message-based interface derived from a common business object model, where the common business object model includes business objects having relationships that enable derivation of message-based interfaces and message packages, the message-based interface exposing at least one service as defined in a service registry, the first message received from a heterogeneous application executing in an environment of computer systems providing message-based services, the first message for querying user feed administrators according to specified selection elements, the first message including a first message package derived from the common business object model, the first message package hierarchically organized in memory based on the common business object model, the first message package including: at a first hierarchical level in the first message package, a user feed administrator query message entity; and at the first hierarchical level in the first message package, a user feed administrator package comprising, at a second hierarchical level in the first message package, a user feed administrator entity, where the user feed administrator entity includes, at a third hierarchical level in the first message package, a universally unique identifier (UUID), a feed user identity UUID, a polling end point web universal resource identifier (URI), and at least one feed user identity entity; program code for processing the first message according to the hierarchical organization of the first message package, where processing the first message includes unpacking the first message package based on the first message package's structure and the first message package's derivation from the common business object model, wherein the particular structure of the first message package is used at least in part to identify the purpose of the first message; and program code for sending a second message to the heterogeneous application responsive to the first message, where the second message includes a second message package derived from the common business object model to provide consistent semantics with the first message package.