1. A non-transitory computer readable medium including program code to provide a message-based interface for exchanging opportunity data, the program code operable when executed by at least one processor to: receive 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 replication of opportunity data, including business transaction information and identification of parties involved in a prospective business transaction, 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, an opportunity replication request message entity; and at the first hierarchical level in the first message package, an opportunity package including, at a second hierarchical level in the first message package, an opportunity entity and a status package: wherein the opportunity entity includes, at a third hierarchical level in the first message package, an identifier, a processing type code and a process status valid since date; and wherein the status package includes, at the third hierarchical level in the first message package, a status entity; and process 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, the specific hierarchical elements at each hierarchical level, and the first message package's derivation from the common business object model, wherein the particular hierarchical organization of the first message package and the specific hierarchical elements at each hierarchical level are used at least in part to identify the purpose of the first message; and send 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.