1. A non-transitory computer readable storage medium including instructions executed by at least one processor for providing message-based services using a service-oriented methodology for implementing an instance of an expense and reimbursement management deployment unit, the instructions operable when executed by the at least one processor to: store an instance of the expense and reimbursement management deployment unit for processing an arrangement made by a company for an employee for expense reporting, where the expense and reimbursement management deployment unit defines the limits of an application-defined transaction for processing an arrangement made by a company for an employee for expense reporting by a set of actions that have atomicity, consistency, isolation, and durability in a database, and wherein the actions associated with the application-defined transaction are performed by at least one process component contained in the expense and reimbursement management deployment unit, wherein each process component comprises a software package realizing a business process and exposing the process component's functionality as at least one service operation, wherein the expense and reimbursement management deployment unit comprises: a maintain expense arrangement operation, a request project task availability information operation, a notify of expense report operation, a request expense report cancellation operation, a notify of settlement result operation, and a notify of settlement result cancellation operation; wherein the service operations of the expense and reimbursement deployment unit are packaged together to be deployed on a single computer system; execute the application-defined transaction for processing the arrangement made by a company for an employee for expense reporting; and present data associated with the executed application-defined transaction for processing the arrangement made by a company for an employee for expense reporting to a graphical user interface.