1. A non-transitory computer readable medium including program code for providing a message-based interface for exchanging information about groups of users collaborating on common tasks using feeds, the medium comprising: program code for receiving 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 and from a heterogeneous application executing in an environment of computer systems providing message-based services, a first message for requesting information about feed collaboration groups, the first message including a first message package hierarchically organized in memory based on and derived from the common business object model, the first message package including: at a first hierarchical level in the first message package, a feed collaboration group query message entity; and at the first hierarchical level in the first message package, a feed collaboration group package comprising a feed collaboration group entity and a member package, the member package including, at a second hierarchical level in the first message package, a member entity, where the feed collaboration group entity includes, at the second hierarchical level in the first message package, a universally unique identifier, an identifier, a type code, an inactive indicator and system administrative data; program code for processing the first message based on the hierarchical organization of the first message package, where processing the first message includes unpacking the first message package based on the hierarchical organization of the first message package and the first message package's deriviation from the common business object model, wherein the particular hierarchical organization 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.