1. A computer readable medium including program code for providing a message-based interface for performing a cost model service, the service exposing at least one service as defined in a service registry, wherein upon execution the program code executes in an environment of computer systems providing message-based services and comprises: program code for receiving, from a service consumer, a first message for processing a cost simulation consisting of cost estimates with various cost sources; program code for invoking a cost model business object, wherein the business object is a logically centralized, semantically disjointed object for representing the cost simulation consisting of cost estimates with various cost sources, and comprises data logically organized as: a cost model root node; a property subordinate node; an item subordinate node and wherein the item node contains: a property subordinate node; and a product cost estimate subordinate node and wherein the product cost estimate node contains: a property subordinate node; a cost component split subordinate node and wherein the cost component split node contains: an element subordinate node and wherein the element node contains: a property subordinate node; and an item subordinate node and wherein the item node contains: a property subordinate node; and a cost component split subordinate node and wherein the cost component split node contains: an element subordinate node and wherein the element node contains: a property subordinate node; and program code for initiating transmission of a message to a heterogeneous second application, executing in the environment of computer systems providing message-based services, based on the data in the cost model business object, the message comprising a cost model create request message entity, a message header package, and a cost model package.