1. A tangible computer readable medium including program code for providing a message-based interface for cancelling an original message sent to accounting, 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 cancellation of posting information previously sent to accounting for an incoming or outgoing invoice or credit memo that includes a first message package derived from the common business object model and hierarchically organized in memory as: an accounting cancellation message entity; and an accounting cancellation package comprising an accounting cancellation entity and a business transaction document reference package, where the accounting cancellation entity includes a base prima nota ID and an origin prima nota type code, where the business transaction document reference package includes an origin prima nota reference, and where the origin prima nota reference includes an ID; and 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 common business object model; 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.